VEX Functions

See VEX contexts to learn about the different contexts (such as surface shaders or displacement shaders) in which the various functions and statements are available. Functions

subtopics

Arrays

array_group

append Adds an item to an array or string.
argsort Returns the indices of a sorted version of an array.
array Efficiently creates an array from its arguments.
foreach Loops over the items in an array, with optional enumeration.
insert Inserts an item, array, or string into an array or string.
isvalidindex Checks if the index given is valid for the array or string given.
len Returns the length of an array.
pop Removes the last element of an array and returns it.
push Adds an item to an array.
removeindex Removes an item at the given index from an array.
removevalue Removes an item from an array.
reorder Reorders items in an array or string.
resize Sets the length of an array.
reverse Returns an array or string in reverse order.
slice Slices a sub-string or sub-array of a string or array.
sort Returns the array sorted in increasing order.
upush Adds a uniform item to an array.

Attributes and Intrinsics

attrib_group

addattrib Adds an attribute to a geometry.
adddetailattrib Adds a detail attribute to a geometry.
addpointattrib Adds a point attribute to a geometry.
addprimattrib Adds a primitive attribute to a geometry.
addvertexattrib Adds a vertex attribute to a geometry.
addvisualizer Appends to a geometry’s visualizer detail attribute.
attrib Reads the value of an attribute from geometry.
attribclass Returns the class of a geometry attribute.
attribdataid Returns the data id of a geometry attribute.
attribsize Returns the size of a geometry attribute.
attribtype Returns the type of a geometry attribute.
attribtypeinfo Returns the transformation metadata of a geometry attribute.
curvearclen Evaluates the length of an arc on a primitive defined by an array of points using parametric uv coordinates.
detail Reads the value of a detail attribute value from a geometry.
detailattrib Reads a detail attribute value from a geometry.
detailattribsize Returns the size of a geometry detail attribute.
detailattribtype Returns the type of a geometry detail attribute.
detailattribtypeinfo Returns the type info of a geometry attribute.
detailintrinsic Reads the value of a detail intrinsic from a geometry.
findattribval Finds a primitive/point/vertex that has a certain attribute value.
findattribvalcount Returns number of elements where an integer or string attribute has a certain value.
getattrib Reads an attribute value from geometry, with validity check.
getattribute Copies the value of a geometry attribute into a variable and returns a success flag.
hasattrib Checks whether a geometry attribute exists.
hasdetailattrib Returns if a geometry detail attribute exists.
haspointattrib Returns if a geometry point attribute exists.
hasprimattrib Returns if a geometry prim attribute exists.
hasvertexattrib Returns if a geometry vertex attribute exists.
idtopoint Finds a point by its id attribute.
idtoprim Finds a primitive by its id attribute.
nametopoint Finds a point by its name attribute.
nametoprim Finds a primitive by its name attribute.
nuniqueval Returns the number of unique values from an integer or string attribute.
point Reads a point attribute value from a geometry.
pointattrib Reads a point attribute value from a geometry and outputs a success/fail flag.
pointattribsize Returns the size of a geometry point attribute.
pointattribtype Returns the type of a geometry point attribute.
pointattribtypeinfo Returns the type info of a geometry attribute.
pointlocaltransforms Returns an array of point localtransforms from an array of point indices.
pointtransform Returns a point transform from a point index.
pointtransformrigid Returns a rigid point transform from a point index.
pointtransforms Returns an array of point transforms from an array of point indices.
pointtransformsrigid Returns an array of rigid point transforms from an array of point indices.
prim Reads a primitive attribute value from a geometry.
prim_attribute Interpolates the value of an attribute at a certain parametric (u, v) position and copies it into a variable.
primarclen Evaluates the length of an arc on a primitive using parametric uv coordinates.
primattrib Reads a primitive attribute value from a geometry, outputting a success flag.
primattribsize Returns the size of a geometry prim attribute.
primattribtype Returns the type of a geometry prim attribute.
primattribtypeinfo Returns the type info of a geometry attribute.
primduv Returns position derivative on a primitive at a certain parametric (u, v) position.
priminteriorweights Finds the indices and weightings of the vertices that will compute an interior point given the UVW coordinates.
primintrinsic Reads a primitive intrinsic from a geometry.
primuv Interpolates the value of an attribute at a certain parametric (uvw) position.
primuvconvert Convert parametric UV locations on curve primitives between different spaces.
removedetailattrib Removes a detail attribute from a geometry.
removepointattrib Removes a point attribute from a geometry.
removepointgroup Removes a point group from a geometry.
removeprimattrib Removes a primitive attribute from a geometry.
removeprimgroup Removes a primitive group from a geometry.
removevertexattrib Removes a vertex attribute from a geometry.
removevertexgroup Removes a vertex group from a geometry.
setattrib Writes an attribute value to geometry.
setattribtypeinfo Sets the meaning of an attribute in geometry.
setdetailattrib Sets a detail attribute in a geometry.
setdetailintrinsic Sets the value of a writeable detail intrinsic attribute.
setpointattrib Sets a point attribute in a geometry.
setpointlocaltransforms Sets an array of point local transforms at the given point indices.
setpointtransform Sets the world space transform of a given point
setpointtransforms Sets an array of point transforms at the given point indices.
setprimattrib Sets a primitive attribute in a geometry.
setprimintrinsic Sets the value of a writeable primitive intrinsic attribute.
setvertexattrib Sets a vertex attribute in a geometry.
uniqueval Returns one of the set of unique values across all values for an int or string attribute.
uniquevals Returns the set of unique values across all values for an int or string attribute.
uvsample Interpolates the value of an attribute at certain UV coordinates using a UV attribute.
vertex Reads a vertex attribute value from a geometry.
vertexattrib Reads a vertex attribute value from a geometry.
vertexattribsize Returns the size of a geometry vertex attribute.
vertexattribtype Returns the type of a geometry vertex attribute.
vertexattribtypeinfo Returns the type info of a geometry attribute.

BSDFs

bsdf_group

albedo Returns the albedo (percentage of reflected light) for a bsdf given the outgoing light direction.
ashikhmin Returns a specular BSDF using the Ashikhmin shading model.
blinn Returns a Blinn BSDF or computes Blinn shading.
chiang Returns a chiang BSDF.
chiang_fur Returns a chiang_fur BSDF.
cone Returns a cone reflection BSDF.
cvex_bsdf Creates a bsdf object from two CVEX shader strings.
diffuse Returns a diffuse BSDF or computes diffuse shading.
eval_bsdf Evaluates a bsdf given two vectors.
getbounces
ggx Returns a ggx BSDF.
hair Returns a BSDF for shading hair.
henyeygreenstein Returns an anisotropic volumetric BSDF, which can scatter light forward or backward.
isotropic Returns an isotropic BSDF, which scatters light equally in all directions.
mask_bsdf Returns new BSDF that only includes the components specified by the mask.
normal_bsdf Returns the normal for the diffuse component of a BSDF.
phong Returns a Phong BSDF or computes Phong shading.
phonglobe
sample_bsdf Samples a BSDF.
solid_angle Computes the solid angle (in steradians) a BSDF function subtends.
split_bsdf Splits a bsdf into its component lobes.
sssapprox Creates an approximate SSS BSDF.

BSDFs

BSDFs_group

specular Returns a specular BSDF or computes specular shading.

CHOP

CHOP_group

chadd Adds new channels to a CHOP node.
chattr Reads from a CHOP attribute.
chattrnames Reads CHOP attribute names of a given attribute class from a CHOP input.
chend Returns the sample number of the last sample in a given CHOP input.
chendf Returns the frame corresponding to the last sample of the input specified.
chendt Returns the time corresponding to the last sample of the input specified.
chindex Returns the channel index from a input given a channel name.
chinput Returns the value of a channel at the specified sample.
chinputlimits Computes the minimum and maximum value of samples in an input channel.
chnames Returns all the CHOP channel names of a given CHOP input.
chnumchan Returns the number of channels in the input specified.
chop Returns the value of a CHOP channel at the specified sample.
choplocal Returns the value of a CHOP local transform channel at the specified sample.
choplocalt Returns the value of a CHOP local transform channel at the specified sample and evaluation time.
chopt Returns the value of a CHOP channel at the specified sample and evaluation time.
chrate Returns the sample rate of the input specified.
chreadbuf Returns the value of CHOP context temporary buffer at the specified index.
chremove Removes channels from a CHOP node.
chremoveattr Removes a CHOP attribute.
chrename Renames a CHOP channel.
chresizebuf Resize the CHOP context temporary buffer
chsetattr Sets the value of a CHOP attribute.
chsetlength Sets the length of the CHOP channel data.
chsetrate Sets the sampling rate of the CHOP channel data.
chsetstart Sets the CHOP start sample in the channel data.
chstart Returns the start sample of the input specified.
chstartf Returns the frame corresponding to the first sample of the input specified.
chstartt Returns the time corresponding to the first sample of the input specified.
chwritebuf Writes a value of CHOP context temporary buffer at the specified index.
isframes Returns 1 if the Vex CHOP’s Unit Menu is currently set to ‘frames’, 0 otherwise.
issamples Returns 1 if the Vex CHOP’s Unit Menu is currently set to ‘samples’, 0 otherwise.
isseconds Returns 1 if the Vex CHOP’s Unit Menu is currently set to ‘seconds’, 0 otherwise.
ninputs Returns the number of inputs.

Channel Primitives

chprim_group

chprim_clear Clears a channel primitive, removing all keys.
chprim_destroykey Destroy an existing key from a channel primitive.
chprim_end Get the end time of a channel primitive.
chprim_eval Evaluate a channel primitive at the given time.
chprim_insertkey Insert a key into a channel primitive.
chprim_keycount Get the number of keys in a channel primitive.
chprim_keytimes Get the key times of a channel primitive.
chprim_keyvalues Get the key values of a channel primitive.
chprim_length Get the length of a channel primitive.
chprim_setkeyaccel Set the acceleration of a channel primitive key.
chprim_setkeyslope Set the slope of a channel primitive key.
chprim_setkeyvalue Set the value of a channel primitive key.
chprim_start Get the start time of a channel primitive.

color

color_group

blackbody Compute the color value of an incandescent black body.
ctransform Transforms between color spaces.
luminance Compute the luminance of the RGB color specified by the parameters.

Conversion

convert_group

atof Converts a string to a float.
atoi Converts a string to an integer.
cracktransform Depending on the value of c, returns the translate (c=0), rotate (c=1), scale (c=2), or shears (c=3) component of the transform (xform).
degrees Converts the argument from radians into degrees.
eulertoquaternion Creates a vector4 representing a quaternion from euler angles.
hsvtorgb Convert HSV color space into RGB color space.
qconvert Converts a quaternion represented by a vector4 to a matrix3 representation.
quaterniontoeuler Creates a euler angle representing a quaternion.
radians Converts the argument from degrees into radians.
rgbtohsv Convert RGB color space to HSV color space.
rgbtoxyz Convert a linear sRGB triplet to CIE XYZ tristimulus values.
serialize Flattens an array of vector or matrix types into an array of floats.
unserialize Turns a flat array of floats into an array of vectors or matrices.
xyztorgb Convert CIE XYZ tristimulus values to a linear sRGB triplet.

Crowds

crowd_group

agentaddclip Add a clip into an agent’s definition.
agentchannelcount Returns the number of channels in an agent primitive’s rig.
agentchannelnames Returns the names of the channels in an agent primitive’s rig.
agentchannelvalue Returns the current value of an agent primitive’s channel.
agentchannelvalues Returns the current values of an agent primitive’s channels.
agentclipcatalog Returns all of the animation clips that have been loaded for an agent primitive.
agentclipchannel Finds the index of a channel in an agent’s animation clip.
agentclipchannelnames Returns the names of the channels in an agent’s animation clip.
agentcliplayerblend Blends values according to an agent’s animation layers.
agentcliplength Returns the length (in seconds) of an agent’s animation clip.
agentclipnames Returns an agent primitive’s current animation clips.
agentclipsample Samples a channel of an agent’s clip at a specific time.
agentclipsamplelocal Samples an agent’s animation clip at a specific time.
agentclipsamplerate Returns the sample rate of an agent’s animation clip.
agentclipsampleworld Samples an agent’s animation clip at a specific time.
agentclipstarttime Returns the start time (in seconds) of an agent’s animation clip.
agentcliptimes Returns the current times for an agent primitive’s animation clips.
agentcliptransformgroups Returns the transform groups for an agent primitive’s current animation clips.
agentclipweights Returns the blend weights for an agent primitive’s animation clips.
agentcollisionlayer Returns the name of the collision layer of an agent primitive.
agentcollisionlayers Returns the names of an agent primitive’s collision layers.
agentcurrentlayer Returns the name of the current layer of an agent primitive.
agentcurrentlayers Returns the names of an agent primitive’s current layers.
agentfindclip Finds the index of a clip in an agent’s definition.
agentfindlayer Finds the index of a layer in an agent’s definition.
agentfindtransformgroup Finds the index of a transform group in an agent’s definition.
agentlayerbindings Returns the transform that each shape in an agent’s layer is bound to.
agentlayers Returns all of the layers that have been loaded for an agent primitive.
agentlayershapes Returns the names of the shapes referenced by an agent primitive’s layer.
agentlocaltransform Returns the current local space transform of an agent primitive’s bone.
agentlocaltransforms Returns the current local space transforms of an agent primitive.
agentmetadata Returns the agent definition’s metadata dictionary.
agentrestlocaltransform Returns the local space rest transform for an agent primitive’s joint.
agentrestworldtransform Returns the world space rest transform for an agent primitive’s joint.
agentrigchildren Returns the child transforms of a transform in an agent primitive’s rig.
agentrigfind Finds the index of a transform in an agent primitive’s rig.
agentrigfindchannel Finds the index of a channel in an agent primitive’s rig.
agentrigparent Returns the parent transform of a transform in an agent primitive’s rig.
agentsolvefbik Applies a full-body inverse kinematics algorithm to an agent’s skeleton.
agenttransformcount Returns the number of transforms in an agent primitive’s rig.
agenttransformgroupmember Returns whether a transform is a member of the specified transform group.
agenttransformgroupmemberchannel Returns whether a channel is a member of the specified transform group.
agenttransformgroups Returns the names of the transform groups in an agent’s definition.
agenttransformgroupweight Returns the weight of a member of the specified transform group.
agenttransformnames Returns the name of each transform in an agent primitive’s rig.
agenttransformtolocal Converts transforms from world space to local space for an agent primitive.
agenttransformtoworld Converts transforms from local space to world space for an agent primitive.
agentworldtransform Returns the current world space transform of an agent primitive’s bone.
agentworldtransforms Returns the current world space transforms of an agent primitive.
setagentchannelvalue Overrides the value of an agent primitive’s channel.
setagentchannelvalues Overrides the values of an agent primitive’s channels.
setagentclipnames Sets the current animation clips for an agent primitive.
setagentclips Sets the animation clips that an agent should use to compute its transforms.
setagentcliptimes Sets the current times for an agent primitive’s animation clips.
setagentclipweights Sets the blend weights for an agent primitive’s animation clips.
setagentcollisionlayer Sets the collision layer of an agent primitive.
setagentcollisionlayers Sets the collision layers of an agent primitive.
setagentcurrentlayer Sets the current layer of an agent primitive.
setagentcurrentlayers Sets the current display layers of an agent primitive.
setagentlocaltransform Overrides the local space transform of an agent primitive’s bone.
setagentlocaltransforms Overrides the local space transforms of an agent primitive.
setagentworldtransform Overrides the world space transform of an agent primitive’s bone.
setagentworldtransforms Overrides the world space transforms of an agent primitive.

dict

dict_group

json_dumps Converts a VEX dictionary into a JSON string.
json_loads Converts a JSON string into a VEX dictionary.
keys Returns all the keys in a dictionary.
typeid Returns a numeric code identifying a VEX data type.

displace

displace_group

dimport Reads a variable from the displacement shader for the surface.

File I/O

file_group

file_stat Returns file system status for a given file.

filter

filter_remap Computes an importance sample based on the given filter type and input uv.

Fuzzy Logic

fuzzy_group

Geometry

geo_group

addpoint Adds a point to the geometry.
addprim Adds a primitive to the geometry.
addvertex Adds a vertex to a primitive in a geometry.
clip Clip the line segment between p0 and p1.
geoself Returns a handle to the current geometry.
geounwrap Returns an oppath: string to unwrap the geometry in-place.
inedgegroup Returns 1 if the edge specified by the point pair is in the group specified by the string.
intersect This function computes the first intersection of a ray with geometry.
intersect_all Computes all intersections of the specified ray with geometry.
minpos Given a position in world space, returns the position of the closest point on a given geometry.
nearpoint Finds the closest point in a geometry.
nearpoints Finds the all the closest point in a geometry.
nedgesgroup Returns the number of edges in the group.
neighbour Returns the point number of the next point connected to a given point.
neighbourcount Returns the number of points that are connected to the specified point.
neighbours Returns an array of the point numbers of the neighbours of a point.
npoints Returns the number of points in the input or geometry file.
nprimitives Returns the number of primitives in the input or geometry file.
nvertices Returns the number of vertices in the input or geometry file.
nverticesgroup Returns the number of vertices in the group.
pointprims Returns the list of primitives containing a point.
pointvertex Returns a linear vertex number of a point in a geometry.
pointvertices Returns the list of vertices connected to a point.
polyneighbours Returns an array of the primitive numbers of the edge-neighbours of a polygon.
primfind Returns a list of primitives potentially intersecting a given bounding box.
primpoint Converts a primitive/vertex pair into a point number.
primpoints Returns the list of points on a primitive.
primvertex Converts a primitive/vertex pair into a linear vertex.
primvertexcount Returns number of vertices in a primitive in a geometry.
primvertices Returns the list of vertices on a primitive.
removeattrib Removes an attribute or group from the geometry.
removepoint Removes a point from the geometry.
removeprim Removes a primitive from the geometry.
removevertex Removes a vertex from the geometry.
setedgegroup Sets edge group membership in a geometry.
setprimvertex Rewires a vertex in the geometry to a different point.
setvertexpoint Rewires a vertex in the geometry to a different point.
uvintersect This function computes the intersection of the specified ray with the geometry in uv space.
vertexcurveparam Returns the parametric coordinate of a vertex along the perimeter of its primitive.
vertexindex Converts a primitive/vertex pair into a linear vertex.
vertexnext Returns the linear vertex number of the next vertex sharing a point with a given vertex.
vertexpoint Returns the point number of linear vertex in a geometry.
vertexprev Returns the linear vertex number of the previous vertex sharing a point with a given vertex.
vertexprim Returns the number of the primitive containing a given vertex.
vertexprimindex Converts a linear vertex index into a primitive vertex number.

groups

groups_group

expandedgegroup
expandpointgroup Returns an array of point numbers corresponding to a group string.
expandprimgroup Returns an array of prim numbers corresponding to a group string.
expandvertexgroup Returns an array of linear vertex numbers corresponding to a group string.
inpointgroup Returns 1 if the point specified by the point number is in the group specified by the string.
inprimgroup Returns 1 if the primitive specified by the primitive number is in the group specified by the string.
invertexgroup Returns 1 if the vertex specified by the vertex number is in the group specified by the string.
npointsgroup Returns the number of points in the group.
nprimitivesgroup Returns the number of primitives in the group.
setpointgroup Adds or removes a point to/from a group in a geometry.
setprimgroup Adds or removes a primitive to/from a group in a geometry.
setvertexgroup Adds or removes a vertex to/from a group in a geometry.

Half-edges

hedge_group

hedge_dstpoint Returns the destination point of a half-edge.
hedge_dstvertex Returns the destination vertex of a half-edge.
hedge_equivcount Returns the number of half-edges equivalent to a given half-edge.
hedge_isequiv Determines whether a two half-edges are equivalent (represent the same edge).
hedge_isprimary Determines whether a half-edge number corresponds to a primary half-edge.
hedge_isvalid Determines whether a half-edge number corresponds to a valid half-edge.
hedge_next Returns the half-edge that follows a given half-edge in its polygon.
hedge_nextequiv Returns the next half-edges equivalent to a given half-edge.
hedge_postdstpoint Returns the point into which the vertex following the destination vertex of a half-edge in its primitive is wired.
hedge_postdstvertex Returns the vertex following the destination vertex of a half-edge in its primitive.
hedge_presrcpoint Returns the point into which the vertex that precedes the source vertex of a half-edge in its primitive is wired.
hedge_presrcvertex Returns the vertex that precedes the source vertex of a half-edge in its primitive.
hedge_prev Returns the half-edge that precedes a given half-edge in its polygon.
hedge_prim Returns the primitive that contains a half-edge.
hedge_primary Returns the primary half-edge equivalent to a given half-edge.
hedge_srcpoint Returns the source point of a half-edge.
hedge_srcvertex Returns the source vertex of a half-edge.
pointedge Finds and returns a half-edge with the given endpoints.
pointhedge Finds and returns a half-edge with a given source point or with given source and destination points.
pointhedgenext Returns the next half-edge with the same source as a given half-edge.
primhedge Returns one of the half-edges contained in a primitive.
vertexhedge Returns the half-edge which has a vertex as source.

hex

hex_group

hex_adjacent Returns primitive number of an adjacent hexahedron.
hex_faceindex Returns vertex indices of each face of a hexahedron.

Image Processing

image_group

accessframe Tells the COP manager that you need access to the given frame.
alphaname Returns the default name of the alpha plane (as it appears in the compositor preferences).
binput Samples a 2×2 pixel block around the given UV position, and bilinearly interpolates these pixels.
bumpname Returns the default name of the bump plane (as it appears in the compositor preferences).
chname Returns the name of a numbered channel.
cinput Samples the exact (unfiltered) pixel color at the given coordinates.
colorname Returns the default name of the color plane (as it appears in the compositor preferences).
depthname Returns the default name of the depth plane (as it appears in the compositor preferences).
dsmpixel Reads the z-records stored in a pixel of a deep shadow map or deep camera map.
finput Returns fully filtered pixel input.
hasmetadata Queries if metadata exists on a composite operator.
hasplane Returns 1 if the plane specified by the parameter exists in this COP.
iaspect Returns the aspect ratio of the specified input.
ichname Returns the channel name of the indexed plane of the given input.
iend Returns the last frame of the specified input.
iendtime Returns the end time of the specified input.
ihasplane Returns 1 if the specified input has a plane named planename.
inumplanes Returns the number of planes in the given input.
iplaneindex Returns the index of the plane named ‘planename’ in the specified input.
iplanename Returns the name of the plane specified by the planeindex of the given input
iplanesize Returns the number of components in the plane named planename in the specified input.
irate Returns the frame rate of the specified input.
istart Returns the starting frame of the specified input.
istarttime Returns the start time of the specified input.
ixres Returns the X resolution of the specified input.
iyres Returns the Y resolution of the specified input.
lumname Returns the default name of the luminaence plane (as it appears in the compositor preferences).
maskname Returns the default name of the mask plane (as it appears in the compositor preferences).
metadata Returns a metadata value from a composite operator.
ninput Reads a component from a pixel and its eight neighbors.
normalname Returns the default name of the normal plane (as it appears in the compositor preferences).
planeindex Returns the index of the plane specified by the parameter, starting at zero.
planename Returns the name of the plane specified by the index (e.
planesize Returns the number of components in the plane (1 for scalar planes and up to 4 for vector planes).
pointname Returns the default name of the point plane (as it appears in the compositor preferences).
velocityname Returns the default name of the velocity plane (as it appears in the compositor preferences).

Interpolation

interp_group

ckspline Samples a Catmull-Rom (Cardinal) spline defined by position/value keys.
clamp Returns value clamped between min and max.
cspline Samples a Catmull-Rom (Cardinal) spline defined by uniformly spaced keys.
efit Takes the value in one range and shifts it to the corresponding value in a new range.
fit Takes the value in one range and shifts it to the corresponding value in a new range.
fit01 Takes the value in the range (0, 1) and shifts it to the corresponding value in a new range.
fit10 Takes the value in the range (1, 0) and shifts it to the corresponding value in a new range.
fit11 Takes the value in the range (-1, 1) and shifts it to the corresponding value in a new range.
invlerp Inverses a linear interpolation between the values.
lerp Performs linear interpolation between the values.
lkspline Samples a polyline between the key points.
lspline Samples a polyline defined by linearly spaced values.
slerp Quaternion blend between q1 and q2 based on the bias.
slerpv Spherical blends between two vectors based on the bias.
smooth Computes ease in/out interpolation between values.

light

light_group

ambient Returns the color of ambient light in the scene.
atten Computes attenuated falloff.
fastshadow Sends a ray from the position P along the direction specified by the direction D.
filtershadow Sends a ray from the position P along direction D.

Math

math_group

abs Returns the absolute value of the argument.
acos Returns the inverse cosine of the argument.
asin Returns the inverse sine of the argument.
atan Returns the inverse tangent of the argument.
atan2 Returns the inverse tangent of y/x.
avg Returns the average value of the input(s)
cbrt Returns the cube root of the argument.
ceil Returns the smallest integer greater than or equal to the argument.
combinelocaltransform Combines Local and Parent Transforms with Scale Inheritance.
cos Returns the cosine of the argument.
cosh Returns the hyperbolic cosine of the argument.
cross Returns the cross product between the two vectors.
determinant Computes the determinant of the matrix.
diag Extracts diagonal entries or constructs a diagonal matrix.
diagonalizesymmetric Diagonalizes Symmetric Matrices.
distance_pointline This function returns the closest distance between the point Q and the infinite line going through O parallel to vector D.
distance_pointray This function returns the closest distance between the point Q and the semi-finite ray starting at O and extending in the direction D.
distance_pointsegment This function returns the closest distance between the point Q and a finite line segment between points P0 and P1.
dot Returns the dot product between the arguments.
Du Returns the derivative of the given value with respect to U.
Dv Returns the derivative of the given value with respect to V.
Dw Returns the derivative of the given value with respect to the 3rd axis (for volume rendering).
eigenvalues Computes the eigenvalues of a 3×3 matrix.
erf Gauss error function.
erf_inv Inverse Gauss error function.
erfc Gauss error function’s complement.
exp Returns the exponential function of the argument.
extractlocaltransform Extracts Local Transform from a World Transform with Scale Inheritance.
floor Returns the largest integer less than or equal to the argument.
frac Returns the fractional component of the floating point number.
ident Returns an identity matrix.
invert Inverts a matrix.
isfinite Checks whether a value is a normal finite number.
isinf Checks whether a value is a positive or negative infinity.
isnan Checks whether a value is not a number.
kspline Returns an interpolated value along a curve defined by a basis and key/position pairs.
length Returns the magnitude of a vector.
length2 Returns the squared distance of the vector or vector4.
log Returns the natural logarithm of the argument.
log10 Returns the logarithm (base 10) of the argument.
makebasis Creates an orthonormal basis given a z-axis vector.
max
min
norm_1 Returns the induced matrix 1-norm.
norm_fro Returns the Frobenius norm of a matrix.
norm_inf Returns the induced matrix infinity-norm.
norm_max Returns the matrix max-norm.
norm_spectral Returns the matrix spectral norm.
normalize Returns a normalized vector.
outerproduct Returns the outer product between the arguments.
pinvert Computes the pseudo-inverse of a matrix.
planesphereintersect Computes the intersection of a 3D sphere and an infinite 3D plane.
pow Raises the first argument to the power of the second argument.
predicate_incircle Determines if a point is inside or outside a triangle circumcircle.
predicate_insphere Determines if a point is inside or outside a tetrahedron circumsphere.
predicate_orient2d Determines the orientation of a point with respect to a line.
predicate_orient3d Determines the orientation of a point with respect to a plane.
premul Pre multiply matrices.
product Returns the product of a list of numbers.
ptlined This function returns the closest distance between the point Q and a finite line segment between points P0 and P1.
qdistance Finds distance between two quaternions.
qinvert Inverts a quaternion rotation.
qmultiply Multiplies two quaternions and returns the result.
qrotate Rotates a vector by a quaternion.
quaternion Creates a vector4 representing a quaternion.
resample_linear
rint Rounds the number to the closest whole number.
shl Bit-shifts an integer left.
shr Bit-shifts an integer right.
shrz Bit-shifts an integer right.
sign Returns -1, 0, or 1 depending on the sign of the argument.
sin Returns the sine of the argument.
sinh Returns the hyperbolic sine of the argument.
slideframe Finds the normal component of frame slid along a curve.
solvecubic Solves a cubic function returning the number of real roots.
solvepoly Finds the real roots of a polynomial.
solvequadratic Solves a quadratic function returning the number of real roots.
solvetriangleSSS Finds the angles of a triangle from its sides.
spline Samples a value along a polyline or spline curve.
spline_cdf Generate a cumulative distribution function (CDF) by sampling a spline curve.
sqrt Returns the square root of the argument.
sum Returns the sum of a list of numbers.
svddecomp Computes the singular value decomposition of a given matrix.
tan Returns the trigonometric tangent of the argument
tanh Returns the hyperbolic tangent of the argument
tr Returns the trace of the given matrix.
transpose Transposes the given matrix.
trunc Removes the fractional part of a floating point number.

measure

measure_group

distance Returns the distance between two points.
distance2 Returns the squared distance between the two points.
getbbox Sets two vectors to the minimum and maximum corners of the bounding box for the geometry.
getbbox_center Returns the center of the bounding box for the geometry.
getbbox_max Returns the maximum of the bounding box for the geometry.
getbbox_min Returns the minimum of the bounding box for the geometry.
getbbox_size Returns the size of the bounding box for the geometry.
getbounds Returns the bounding box of the geometry specified by the filename.
getpointbbox Sets two vectors to the minimum and maximum corners of the bounding box for the geometry.
getpointbbox_center Returns the center of the bounding box for the geometry.
getpointbbox_max Returns the maximum of the bounding box for the geometry.
getpointbbox_min Returns the minimum of the bounding box for the geometry.
getpointbbox_size Returns the size of the bounding box for the geometry.
planepointdistance Computes the distance and closest point of a point to an infinite plane.
relbbox Returns the relative position of the point given with respect to the bounding box of the geometry.
relpointbbox Returns the relative position of the point given with respect to the bounding box of the geometry.
surfacedist Finds the distance of a point to a group of points along the surface of a geometry.
uvdist Finds the distance of a uv coordinate to a geometry in uv space.
windingnumber Computes the winding number of a mesh around a point. Winding number indicates how many times a geometry wraps around a point. Useful for inside/outside test, the winding number is equal to one inside of the mesh and zero outside.
windingnumber2d Computes the winding number of a curve in XY plane around a point. Winding number indicates how many times a curve wraps around a point. Useful for inside/outside test, the winding number is equal to one inside of the curve and zero outside.
xyzdist Finds the distance from a point to the closest location on surface geometry.

metaball

metaball_group

metaimport Once you get a handle to a metaball using metastart and metanext, you can query attributes of the metaball with metaimport.
metamarch Takes the ray defined by p0 and p1 and partitions it into zero or more sub-intervals where each interval intersects a cluster of metaballs from filename.
metanext Iterate to the next metaball in the list of metaballs returned by the metastart() function.
metastart Open a geometry file and return a handle for the metaballs of interest, at the position p.
metaweight Returns the metaweight of the geometry at position p.

Nodes

nodes_group

addvariablename Adds a mapping for an attribute to a local variable.
ch Evaluates a channel (or parameter) and return its value.
ch2 Evaluates a channel (or parameter) and return its value.
ch3 Evaluates a channel (or parameter) and return its value.
ch4 Evaluates a channel (or parameter) and return its value.
chdict Evaluates a key-value dictionary parameter and return its value.
chexpr Evaluates a channel with a new segment expression.
chexprf Evaluates a channel with a new segment expression at a given frame.
chexprt Evaluates a channel with a new segment expression at a given time.
chf Evaluates a channel (or parameter) and return its value.
chi Evaluates a channel (or parameter) and return its value.
chid Resolves a channel string (or parameter) and return op_id, parm_index and vector_index.
chp Evaluates a channel (or parameter) and return its value.
chramp Evaluates a ramp parameter and return its value.
chrampderiv Evaluates the derivative of a parm parameter with respect to position.
chs Evaluates a channel (or parameter) and return its value.
chsop Evaluates an operator path parameter and return the path to the operator.
chsraw Returns the raw string channel (or parameter).
chu Evaluates a channel or parameter, and return its value.
chv Evaluates a channel or parameter, and return its value.
cregioncapturetransform Returns the capture transform associated with a Capture Region SOP.
cregiondeformtransform Returns the deform transform associated with a Capture Region SOP.
cregionoverridetransform Returns the capture or deform transform associated with a Capture Region SOP based on the global capture override flag.
isconnected Returns 1 if input_number is connected, or 0 if the input is not connected.
opfullpath Returns the full path for the given relative path
opid Resolves an operator path string and return its op_id.
opparentbonetransform Returns the parent bone transform associated with an OP.
opparenttransform Returns the parent transform associated with an OP.
opparmtransform Returns the parm transform associated with an OP.
oppreconstrainttransform Returns the preconstraint transform associated with an OP.
oppreparmtransform Returns the pre and parm transform associated with an OP.
opprerawparmtransform Returns the pre and raw parm transform associated with an OP.
oppretransform Returns the pretransform associated with an OP.
oprawparmtransform Returns the raw parm transform associated with an OP.
optransform Returns the transform associated with an OP.

Noise and Randomness

noise_group

anoise Generates alligator noise.
curlgxnoise Computes divergence free noise based on simplex noise.
curlgxnoise2d Computes divergence free noise in the plane based on simplex noise.
curlnoise Computes divergence free noise based on Perlin noise.
curlnoise2d Computes 2d divergence free noise based on Perlin noise.
curlxnoise Computes divergence free noise based on Simplex noise.
curlxnoise2d Computes 2d divergence free noise based on simplex noise.
cwnoise Generates Worley (cellular) noise using a Chebyshev distance metric.
flownoise Generates 1D and 3D Perlin Flow Noise from 3D and 4D data.
flowpnoise There are two forms of Perlin-style noise: a non-periodic noise which changes randomly throughout N-dimensional space, and a periodic form which repeats over a given range of space.
gxnoise Evaluates a simplex noise field.
gxnoised Evaluates a simplex noise field and its derivatives.
hscript_noise Generates noise matching the output of the Hscript noise() expression function.
hscript_rand Produces the exact same results as the Houdini expression function of the same name.
hscript_snoise
hscript_sturb
hscript_turb Generates turbulence matching the output of the HScript turb() expression function.
mwnoise Generates Worley (cellular) noise using a Manhattan distance metric.
mx_cellnoise MaterialX compatible cellnoise
mx_perlin MaterialX compatible Perlin noise
mx_voronoi MaterialX compatible Voronoi noise
mx_worley MaterialX compatible Worley noise
noise There are two forms of Perlin-style noise: a non-periodic noise which changes randomly throughout N-dimensional space, and a periodic form which repeats over a given range of space.
noised Derivatives of Perlin Noise.
nrandom Non-deterministic random number generation function.
onoise These functions are similar to wnoise and vnoise.
pnoise There are two forms of Perlin-style noise: a non-periodic noise which changes randomly throughout N-dimensional space, and a periodic form which repeats over a given range of space.
pxnoised Periodic derivatives of Simplex Noise.
rand Creates a random number between 0 and 1 from a seed.
random Generate a random number based on the integer position in 1-4D space.
random_brj Generate a uniformly distributed random number.
random_fhash Hashes floating point numbers to integers.
random_ihash Hashes integer numbers to integers.
random_poisson Generates a random Poisson variable given the mean to the distribution and a seed.
random_shash Hashes a string to an integer.
random_sobol Generate a uniformly distributed random number.
snoise These functions are similar to wnoise.
vnoise Generates Voronoi (cellular) noise.
wnoise Generates Worley (cellular) noise.
xnoise Simplex noise is very close to Perlin noise, except with the samples on a simplex mesh rather than a grid. This results in less grid artifacts. It also uses a higher order bspline to provide better derivatives. This is the periodic simplex noise
xnoise Simplex noise is very close to Perlin noise, except with the samples on a simplex mesh rather than a grid. This results in less grid artifacts. It also uses a higher order bspline to provide better derivatives.
xnoised Derivatives of Simplex Noise.

normals

normals_group

computenormal In shading contexts, computes a normal. In the SOP contexts, sets how/whether to recompute normals.
prim_normal Returns the normal of the primitive (prim_number) at parametric location u, v.

Open Color IO

ocio_group

ocio_activedisplays Returns the names of active displays supported in Open Color IO
ocio_activeviews Returns the names of active views supported in Open Color IO
ocio_import Imports attributes from OpenColorIO spaces.
ocio_parsecolorspace Parse the color space from a string
ocio_roles Returns the names of roles supported in Open Color IO
ocio_spaces Returns the names of color spaces supported in Open Color IO.
ocio_transform Transform colors using Open Color IO
ocio_transformview Transform colors to a view using Open Color IO

particles

particles_group

filamentsample Samples the velocity field defined by a set of vortex filaments.

Point Clouds and 3D Images

ptcloud_group

mattrib Returns the value of the point attribute for the metaballs if metaball geometry is specified to i3dgen.
mdensity Returns the density of the metaball field if metaball geometry is specified to i3dgen.
mspace Transforms the position specified into the local space of the metaball.
pcclose This function closes the handle associated with a pcopen function.
pccone Returns a list of closest points from a file within a specified cone.
pccone_radius Returns a list of closest points from a file in a cone, taking into account their radii
pcconvex
pcexport Writes data to a point cloud inside a pciterate or a pcunshaded loop.
pcfarthest Returns the distance to the farthest point found in the search performed by pcopen.
pcfilter Filters points found by pcopen using a simple reconstruction filter.
pcfind Returns a list of closest points from a file.
pcfind_radius Returns a list of closest points from a file taking into account their radii.
pcgenerate Generates a point cloud.
pcimport Imports channel data from a point cloud inside a pciterate or a pcunshaded loop.
pcimportbyidx3 Imports channel data from a point cloud outside a pciterate or a pcunshaded loop.
pcimportbyidx4 Imports channel data from a point cloud outside a pciterate or a pcunshaded loop.
pcimportbyidxf Imports channel data from a point cloud outside a pciterate or a pcunshaded loop.
pcimportbyidxi Imports channel data from a point cloud outside a pciterate or a pcunshaded loop.
pcimportbyidxp Imports channel data from a point cloud outside a pciterate or a pcunshaded loop.
pcimportbyidxs Imports channel data from a point cloud outside a pciterate or a pcunshaded loop.
pcimportbyidxv Imports channel data from a point cloud outside a pciterate or a pcunshaded loop.
pciterate This function can be used to iterate over all the points which were found in the pcopen query.
pcline Returns a list of closest points to an infinite line from a specified file
pcline_radius Returns a list of closest points to an infinite line from a specified file
pcnumfound This node returns the number of points found by pcopen.
pcopen Returns a handle to a point cloud file.
pcopenlod Returns a handle to a point cloud file.
pcsampleleaf Changes the current iteration point to a leaf descendant of the current aggregate point.
pcsegment Returns a list of closest points to a line segment from a specified file
pcsegment_radius Returns a list of closest points to a line segment from a specified file
pcsize
pcunshaded Iterate over all of the points of a read-write channel which haven’t had any data written to the channel yet.
pcwrite Writes data to a point cloud file.
pgfind Returns a list of closest points from a file.
photonmap Samples a color from a photon map.
texture3d Returns the value of the 3d image at the position specified by P.
texture3dBox This function queries the 3D texture map specified and returns the bounding box information of the file.

Sampling

sampling_group

create_cdf Creates a cumulative distribution function (CDF) from an array of probability density function (PDF) values.
create_pdf Creates a probability density function from an array of input values.
limit_sample_space Limits a unit value in a way that maintains uniformity and in-range consistency.
newsampler Initializes a sampling sequence for the nextsample function.
nextsample
sample_cauchy Samples the Cauchy (Lorentz) distribution.
sample_cdf Samples a cumulative distribution function (CDF).
sample_circle_arc Generates a uniform unit vector2, within maxangle of center, given a uniform number between 0 and 1.
sample_circle_edge_uniform Generates a uniform unit vector2, given a uniform number between 0 and 1.
sample_circle_ring_uniform Generates a uniform vector2 with alpha < length < 1, where 0 < alpha < 1, given a vector2 of uniform numbers between 0 and 1.
sample_circle_slice Generates a uniform vector2 with length < 1, within maxangle of center, given a vector2 of uniform numbers between 0 and 1.
sample_circle_uniform Generates a uniform vector2 with length < 1, given a vector2 of uniform numbers between 0 and 1.
sample_direction_cone Generates a uniform unit vector, within maxangle of center, given a vector2 of uniform numbers between 0 and 1.
sample_direction_uniform Generates a uniform unit vector, given a vector2 of uniform numbers between 0 and 1.
sample_discrete Returns an integer, either uniform or weighted, given a uniform number between 0 and 1.
sample_exponential Samples the exponential distribution.
sample_geometry Samples geometry in the scene and returns information from the shaders of surfaces that were sampled.
sample_hemisphere Generates a unit vector, optionally biased, within a hemisphere, given a vector2 of uniform numbers between 0 and 1.
sample_hypersphere_cone Generates a uniform vector4 with length < 1, within maxangle of center, given a vector4 of uniform numbers between 0 and 1.
sample_hypersphere_uniform Generates a uniform vector4 with length < 1, given a vector4 of uniform numbers between 0 and 1.
sample_light Samples a 3D position on a light source and runs the light shader at that point.
sample_lognormal Samples the log-normal distribution based on parameters of the underlying normal distribution.
sample_lognormal_by_median Samples the log-normal distribution based on median and standard deviation.
sample_normal Samples the normal (Gaussian) distribution.
sample_orientation_cone Generates a uniform unit vector4, within maxangle of center, given a vector of uniform numbers between 0 and 1.
sample_orientation_uniform Generates a uniform unit vector4, given a vector of uniform numbers between 0 and 1.
sample_photon Samples a 3D position on a light source and runs the light shader at that point.
sample_sphere_cone Generates a uniform vector with length < 1, within maxangle of center, given a vector of uniform numbers between 0 and 1.
sample_sphere_shell_uniform Generates a uniform vector with alpha < length < 1, where 0 < alpha < 1, given a vector of uniform numbers between 0 and 1.
sample_sphere_uniform Generates a uniform vector with length < 1, given a vector of uniform numbers between 0 and 1.
sampledisk Warps uniform random samples to a disk.
variance Computes the mean value and variance for a value.

Sensor Input

sensor_group

sensor_panorama_create Sensor function to render GL scene and query the result.
sensor_panorama_getcolor Sensor function query a rendered GL scene.
sensor_panorama_getcone Sensor function to query average values from rendered GL scene.
sensor_panorama_getdepth Sensor function query a rendered GL scene.
sensor_save Sensor function to save a rendered GL scene.

Shading and Rendering

shading_group

area Returns the area of the micropolygon containing a variable such as P.
blinnBRDF
bouncelabel
bouncemask
diffuseBRDF
filterstep Returns the anti-aliased weight of the step function.
fresnel Computes the fresnel reflection/refraction contributions given an incoming vector, surface normal (both normalized), and an index of refraction (eta).
frontface If dot(I, Nref) is less than zero, N will be negated.
gather Sends rays into the scene and returns information from the shaders of surfaces hit by the rays.
getblurP Returns the blurred point position (P) vector at a fractional time within the motion blur exposure.
getcomponents
getderiv Evaluates surface derivatives of an attribute.
getfogname Returns the name of the current object whose shader is being run.
getglobalraylevel Returns the depth of the ray tree for computing global illumination.
getgroupid Returns group id containing current primitive.
getlight Returns a light struct for the specified light identifier.
getlightid Returns the light id for a named light (or -1 for an invalid name).
getlightname Returns the name of the current light when called from within an illuminance loop, or converts an integer light ID into the light’s name.
getlights Returns an array of light identifiers for the currently shaded surface.
getlightscope Returns a selection of lights that illuminate a given material.
getlocalcurvature Evaluates local curvature of primitive grid, using the same curvature evaluation method as Measure SOPs.
getmaterial Returns a material struct for the current surface.
getmaterialid Returns material id of shaded primitive.
getobjectid Returns the object id for the current shading context.
getobjectname Returns the name of the current object whose shader is being run.
getphotonlight Returns the integer ID of the light being used for photon shading.
getprimid Returns the number of the current primitive.
getptextureid Returns the ptexture face id for the current primitive.
getraylevel Returns the depth of the ray tree for the current shading.
getrayweight Returns an approximation to the contribution of the ray to the final pixel color.
getsamplestore Looks up sample data in a channel, referenced by a point.
getscope Returns a selection of objects visible to rays for a given material.
getsmoothP Returns modified surface position based on a smoothing function.
getuvtangents Evaluates UV tangents at a point on an arbitrary object.
gradient Returns the gradient of a field.
haslight Returns whether a light illuminates the given material.
illuminance Loops through all light sources in the scene, calling the light shader for each light source to set the Cl and L global variables.
integratehoseksky Computes irradiance from the given Hosek Sky on a horizontal surface
interpolate Interpolates a value across the currently shaded micropolygon.
intersect_lights Finds the nearest intersection of a ray with any of a list of (area) lights and runs the light shader at the intersection point.
irradiance Computes irradiance (global illumination) at the point P with the normal N.
isfogray Returns 1 if the shader is being called to evaluate illumination for fog objects, or 0 if the light or shadow shader is being called to evaluate surface illumination.
islpeactive Returns 1 if Light Path Expressions are enabled. 0 Otherwise.
israytracing Indicates whether a shader is being executed for ray tracing.
isshadingRHS Detects the orientation of default shading space.
isshadowray Returns 1 if the shader is being called to evaluate opacity for shadow rays, or 0 if the shader is being called to evaluate for surface color.
isuvrendering Indicates whether the shader is being evaluated while doing UV rendering (e.g. texture unwrapping)
lightbounces Returns the bounce mask for a light struct.
lightid Returns the light id for a light struct.
lightstate Queries the renderer for a named property.
limport Imports a variable from the light shader for the surface.
matchvex_blinn Returns a BSDF that matches the output of the traditional VEX blinn function.
matchvex_specular Returns a BSDF that matches the output of the traditional VEX specular function.
nbouncetypes
objectstate Queries the renderer for a named property.
occlusion Computes ambient occlusion.
pathtrace Computes global illumination using PBR for secondary bounces.
phongBRDF
rayhittest Sends a ray from the position P along the direction D.
rayimport Imports a value sent by a shader in a gather loop.
reflect Returns the vector representing the reflection of the direction against the normal.
reflectlight Computes the amount of reflected light which hits the surface.
refract Returns the refraction ray given an incoming direction, the normalized normal and an index of refraction.
refractlight Computes the illumination of surfaces refracted by the current surface.
renderstate Queries the renderer for a named property.
resolvemissedray Returns the background color for rays that exit the scene.
scatter Evaluates a scattering event through the domain of a geometric object.
setcurrentlight Sets the current light
setsamplestore Stores sample data in a channel, referenced by a point.
shadow Calls shadow shaders for the current light source.
shadow_light Executes the shadow shader for a given light and returns the amount of shadowing as a multiplier of the shaded color.
shimport Imports a variable from the shadow shader for the surface.
simport Imports a variable sent by a surface shader in an illuminance loop.
specularBRDF Returns the computed BRDFs for the different lighting models used in VEX shading.
storelightexport Stores exported data for a light.
switch Use a different bsdf for direct or indirect lighting.
trace Sends a ray from P along the normalized vector D.
translucent Returns a Lambertian translucence BSDF.
uvunwrap Computes the position and normal at given (u, v) coordinates, for use in a lens shader.
wireblinn
wirediffuse
writepixel Writes color information to a pixel in the output image

Strings

string_group

abspath Returns the full path of a file.
chr Converts an unicode codepoint to a UTF8 string.
concat Concatenate all the strings specified to form a single string.
decode Decodes a variable name that was previously encoded.
decodeattrib Decodes a geometry attribute name that was previously encoded.
decodeparm Decodes a node parameter name that was previously encoded.
decodeutf8 Decodes a UTF8 string into a series of codepoints.
encode Encodes any string into a valid variable name.
encodeattrib Encodes any string into a valid geometry attribute name.
encodeparm Encodes any string into a valid node parameter name.
encodeutf8 Encodes a UTF8 string from a series of codepoints.
endswith Indicates the string ends with the specified string.
find Finds an item in an array or string.
isalpha Returns 1 if all the characters in the string are alphabetic
isdigit Returns 1 if all the characters in the string are numeric
itoa Converts an integer to a string.
join Concatenate all the strings of an array inserting a common spacer.
lstrip Strips leading whitespace from a string.
makevalidvarname Forces a string to conform to the rules for variable names.
match This function returns 1 if the subject matches the pattern specified, or 0 if the subject doesn’t match.
opdigits Returns the integer value of the last sequence of digits of a string
ord Converts an UTF8 string into a codepoint.
pluralize Converts an English noun to its plural.
re_find Matches a regular expression in a string
re_findall Finds all instances of the given regular expression in the string
re_match Returns 1 if the entire input string matches the expression
re_replace Replaces instances of regex_find with regex_replace
re_split Splits the given string based on regex match.
relativepath Computes the relative path for two full paths.
relpath Returns the relative path to a file.
replace Replaces occurrences of a substring.
replace_match Replaces the matched string pattern with another pattern.
rstrip Strips trailing whitespace from a string.
split Splits a string into tokens.
splitpath Splits a file path into the directory and name parts.
sprintf Formats a string like printf but returns the result as a string instead of printing it.
startswith Returns 1 if the string starts with the specified string.
strip Strips leading and trailing whitespace from a string.
strlen Returns the length of the string.
titlecase Returns a string that is the titlecase version of the input string.
tolower Converts all characters in string to lower case
toupper Converts all characters in string to upper case

Subdivision Surfaces

subd_group

osd_facecount
osd_firstpatch
osd_limitsurface Evaluates a point attribute at the subdivision limit surface using Open Subdiv.
osd_limitsurfacevertex Evaluates a vertex attribute at the subdivision limit surface using Open Subdiv.
osd_lookupface Outputs the Houdini face and UV coordinates corresponding to the given coordinates on an OSD patch.
osd_lookuppatch Outputs the OSD patch and UV coordinates corresponding to the given coordinates on a Houdini polygon face.
osd_patchcount
osd_patches Returns a list of patch IDs for the patches in a subdivision hull.

Tetrahedrons

tet_group

tet_adjacent Returns primitive number of an adjacent tetrahedron.
tet_faceindex Returns vertex indices of each face of a tetrahedron.

Texturing

texture_group

colormap Looks up a (filtered) color from a texture file.
depthmap The depthmap functions work on an image which was rendered as a z-depth image from mantra.
environment Returns the color of the environment texture.
expand_udim Perform UDIM or UVTILE texture filename expansion.
has_udim Test string for UDIM or UVTILE patterns.
importance_remap Remaps a texture coordinate to another coordinate in the map to optimize sampling of brighter areas.
ocean_sample Evaluates an ocean spectrum and samples the result at a given time and location.
ptexture Computes a filtered sample from a ptex texture map. Use texture instead.
rawcolormap Looks up an unfiltered color from a texture file.
shadowmap The shadowmap function will treat the shadow map as if the image were rendered from a light source.
teximport Imports attributes from texture files.
texprintf Similar to sprintf, but does expansion of UDIM or UVTILE texture filename expansion.
texture Computes a filtered sample of the texture map specified.

Transforms and Space

transform_group

dihedral Computes the rotation matrix or quaternion which rotates the vector a onto the vector b.
fromNDC Transforms a position from normal device coordinates to the coordinates in the appropriate space.
getpackedtransform Gets the transform of a packed primitive.
getspace Returns a transform from one space to another.
instance Creates an instance transform matrix.
lookat Computes a rotation matrix or angles to orient the negative z-axis along the vector (to-from) under the transformation.
maketransform Builds a 3×3 or 4×4 transform matrix.
ndcdepth Returns the camera space z-depth of the NDC z-depth value.
ntransform Transforms a normal vector.
orthographic Create an orthographic projection matrix.
ow_nspace Transforms a normal vector from Object to World space.
ow_space Transforms a position value from Object to World space.
ow_vspace Transforms a direction vector from Object to World space.
packedtransform Transforms a packed primitive.
perspective Create a perspective projection matrix.
polardecomp Computes the polar decomposition of a matrix.
prerotate Applies a pre rotation to the given matrix.
prescale Prescales the given matrix in three directions simultaneously (X, Y, Z - given by the components of the scale_vector).
pretranslate Pretranslates a matrix by a vector.
ptransform Transforms a vector from one space to another.
rotate Applies a rotation to the given matrix.
rotate_x_to Rotates a vector by a rotation that would bring the x-axis to a given direction.
scale Scales the given matrix in three directions simultaneously (X, Y, Z - given by the components of the scale_vector).
setpackedtransform Sets the transform of a packed primitive.
smoothrotation Returns the closest equivalent Euler rotations to a reference rotation.
solveconstraint Applies an inverse kinematics algorithm to a skeleton.
solvecurve Applies a curve inverse kinematics algorithm to a skeleton.
solvefbik Applies a full-body inverse kinematics algorithm to a skeleton.
solveik Applies an inverse kinematics algorithm to a skeleton.
solvephysfbik Applies a full-body inverse kinematics algorithm to a skeleton, with optional control over the center of mass.
toNDC Transforms a position into normal device coordinates.
translate Translates a matrix by a vector.
tw_nspace Transforms a normal vector from Texture to World space.
tw_space Transforms a position value from Texture to World space.
tw_vspace Transforms a direction vector from Texture to World space.
vtransform Transforms a directional vector.
wo_nspace Transforms a normal vector from World to Object space.
wo_space Transforms a position value from World to Object space.
wo_vspace Transforms a direction vector from World to Object space.
wt_nspace Transforms a normal vector from World to Texture space.
wt_space Transforms a position value from World to Texture space.
wt_vspace Transforms a direction vector from World to Texture space.

usd

usd_group

usd_addattrib Creates an attribute of a given type on a primitive.
usd_addcollectionexclude Excludes an object from the collection
usd_addcollectioninclude Includes an object in the collection
usd_addinversetotransformorder Appends an inversed transform operation to the primitive’s transform order
usd_addorient Applies a quaternion orientation to the primitive
usd_addprim Creates a primitive of a given type.
usd_addprimvar Creates a primvar of a given type on a primitive.
usd_addrelationshiptarget Adds a target to the primitive’s relationship
usd_addrotate Applies a rotation to the primitive
usd_addscale Applies a scale to the primitive
usd_addschemaattrib Creates an attribute of a given type on a primitive, and sets the custom metadata flag to False.
usd_addtotransformorder Appends a transform operation to the primitive’s transform order
usd_addtransform Applies a transformation to the primitive
usd_addtranslate Applies a translation to the primitive
usd_applyapi Apply an API schema to a primitive.
usd_attrib Reads the value of an attribute from the USD primitive.
usd_attribelement Reads the value of an element from an array attribute.
usd_attriblen Returns the length of the array attribute.
usd_attribnames Returns the names of the attributes available on the primitive.
usd_attribsize Returns the tuple size of the attribute.
usd_attribtimesamples Returns the time codes at which the attribute values are authored.
usd_attribtypename Returns the name of the attribute type.
usd_blockattrib Blocks the attribute.
usd_blockprimvar Blocks the primvar.
usd_blockprimvarindices Blocks the primvar.
usd_blockrelationship Blocks the primitive’s relationship
usd_boundmaterialpath Returns the material path bound to a given primitive.
usd_childnames Returns the names of the primitive’s children.
usd_clearmetadata Clears the value of the metadata.
usd_cleartransformorder Clears the primitive’s transform order
usd_collectioncomputedpaths Obtains the list of all objects that belong to the collection
usd_collectioncontains Checks if an object path belongs to the collection
usd_collectionexcludes Obtains the object paths that are in the collection’s exclude list
usd_collectionexpansionrule Obtains the collection’s expansion rule
usd_collectionincludes Obtains the object paths that are in the collection’s include list
usd_drawmode Returns the primitive’s draw mode.
usd_findtransformname Retrurns primitive’s transform operation full name for given the transform operation suffix
usd_flattenediprimvar Reads the value of a flattened primvar directly from the USD primitive or from USD primitive’s ancestor.
usd_flattenediprimvarelement Reads an element value of a flattened array primvar directly from the USD primitive or from its ancestor.
usd_flattenedprimvar Reads the value of an flattened primvar directly from the USD primitive.
usd_flattenedprimvarelement Reads an element value of a flattened array primvar directly from a USD primitive.
usd_getbbox Sets two vectors to the minimum and maximum corners of the bounding box for the primitive.
usd_getbbox_center Returns the center of the bounding box for the primitive.
usd_getbbox_max Returns the maximum of the bounding box for the primitive.
usd_getbbox_min Returns the minimum of the bounding box for the primitive.
usd_getbbox_size Returns the size of the bounding box for the primitive.
usd_getbounds Obtains the primitive’s bounds
usd_getpointinstancebounds Obtains the primitive’s bounds
usd_hasapi Checks if the primitive adheres to the given API.
usd_haspayload Checks if the primitive adheres to the given API.
usd_iprimvar Reads the value of a primvar directly from the USD primitive or from USD primitive’s ancestor.
usd_iprimvarelement Reads the value of an element from the array primvar directly from the USD primitive or from USD primitive’s ancestor.
usd_iprimvarelementsize Returns the element size of the primvar directly from the USD primitive or from USD primitive’s ancestor.
usd_iprimvarindices Returns the index array of an indexed primvar directly on the USD primitive or on USD primitive’s ancestor.
usd_iprimvarinterpolation Returns the element size of the primvar directly on the USD primitive or on USD primitive’s ancestor.
usd_iprimvarlen Returns the length of the array primvar directly on the USD primitive or on USD primitive’s ancestor.
usd_iprimvarnames Returns the names of the primvars available directly on the given USD primitive or on USD primitive’s ancestor.
usd_iprimvarsize Returns the tuple size of the primvar directly on the USD primitive or on USD primitive’s ancestor.
usd_iprimvartimesamples Returns the time codes at which the primvar values are authored directly on the given primitive or on its ancestor.
usd_iprimvartypename Returns the name of the primvar type found on the given primitive or its ancestor.
usd_isabstract Checks if the primitive is abstract.
usd_isactive Checks if the primitive is active.
usd_isarray Checks if the attribute is an array.
usd_isarrayiprimvar Checks if there is an array primvar directly on the USD primitive or on USD primitive’s ancestor.
usd_isarraymetadata Checks if the given metadata is an array.
usd_isarrayprimvar Checks if there is an array primvar directly on the USD primitive.
usd_isattrib Checks if the primitive has an attribute by the given name.
usd_iscollection Checks if the collection exists.
usd_iscollectionpath Checks if the path is a valid collection path.
usd_isindexediprimvar Checks if there is an indexed primvar directly on the USD primitive or on USD primitive’s ancestor.
usd_isindexedprimvar Checks if there is an indexed primvar directly on the USD primitive.
usd_isinstance Checks if the primitive is an instance.
usd_isiprimvar Checks if the primitive or its ancestor has a primvar of the given name.
usd_iskind Checks if the primitive is of a given kind.
usd_ismetadata Checks if the primitive has metadata by the given name.
usd_ismodel Checks if the primitive is a model.
usd_isprim Checks if the path refers to a valid primitive.
usd_isprimvar Checks if the primitive has a primvar of the given name.
usd_isrelationship Checks if the primitive has a relationship by the given name.
usd_isstage Checks if the stage is valid.
usd_istransformreset Checks if the primitive transform is reset
usd_istype Checks if the primitive is of a given type.
usd_isvisible Checks if the primitive is visible.
usd_kind Returns the primitive’s kind.
usd_localtransform Obtains the primitive’s local transform
usd_makeattribpath Constructs an attribute path from a primitive path and an attribute name.
usd_makecollectionpath Constructs a collection path from a primitive path and a collection name.
usd_makepropertypath Constructs an property path from a primitive path and an property name.
usd_makerelationshippath Constructs an relationship path from a primitive path and a relationship name.
usd_makevalidprimname Forces a string to conform to the rules for naming USD primitives.
usd_makevalidprimpath Forces a string to conform to the rules for paths to USD primitives.
usd_metadata Reads the value of metadata from the USD object.
usd_metadataelement Reads the value of an element from the array metadata.
usd_metadatalen Returns the length of the array metadata.
usd_metadatanames Returns the names of the metadata available on the object.
usd_name Returns the name of the primitive.
usd_parentpath Returns the path of the primitive’s parent.
usd_pointinstance_getbbox Sets two vectors to the minimum and maximum corners of the bounding box for the given instance inside point instancer.
usd_pointinstance_getbbox_center Returns the center of the bounding box for the instance inside a point instancer primitive.
usd_pointinstance_getbbox_max Returns the maximum position of the bounding box for the instance inside a point instancer primitive.
usd_pointinstance_getbbox_min Returns the minimum position of the bounding box for the instance inside a point instancer primitive.
usd_pointinstance_getbbox_size Returns the size of the bounding box for the instance inside a point instancer primitive.
usd_pointinstance_relbbox Returns the relative position of the point given with respect to the bounding box of the geometry.
usd_pointinstancetransform Obtains the transform for the given point instance
usd_primvar Reads the value of a primvar directly from the USD primitive.
usd_primvarattribname Returns the namespaced attribute name for the given primvar.
usd_primvarelement Reads the value of an element from the array primvar directly from the USD primitive.
usd_primvarelementsize Returns the element size of the primvar directly from the USD primitive.
usd_primvarindices Returns the index array of an indexed primvar directly on the USD primitive.
usd_primvarinterpolation Returns the element size of the primvar directly on the USD primitive.
usd_primvarlen Returns the length of the array primvar directly on the USD primitive.
usd_primvarnames Returns the names of the primvars available on the given USD primitive.
usd_primvarsize Returns the tuple size of the primvar directly on the USD primitive.
usd_primvartimesamples Returns the time codes at which the primvar values are authored directly on the given primitive.
usd_primvartypename Returns the name of the primvar type found on the given primitive.
usd_purpose Returns the primitive’s purpose.
usd_relationshipforwardedtargets Obtains the relationship forwarded targets.
usd_relationshipnames Returns the names of the relationships available on the primitive.
usd_relationshiptargets Obtains the relationship targets.
usd_relbbox Returns the relative position of the point given with respect to the bounding box of the geometry.
usd_removerelationshiptarget Remove a target from the primitive’s relationship
usd_setactive Sets the primitive active state.
usd_setattrib Sets the value of an attribute.
usd_setattribelement Sets the value of an element in an array attribute.
usd_setcollectionexcludes Sets the excludes list on the collection
usd_setcollectionexpansionrule Sets the expansion rule on the collection
usd_setcollectionincludes Sets the includes list on the collection
usd_setdrawmode Sets the primitive’s draw mode.
usd_setkind Sets the primitive’s kind.
usd_setmetadata Sets the value of an metadata.
usd_setmetadataelement Sets the value of an element in an array metadata.
usd_setprimvar Sets the value of a primvar.
usd_setprimvarelement Sets the value of an element in an array primvar.
usd_setprimvarelementsize Sets the element size of a primvar.
usd_setprimvarindices Sets the indices for the given primvar.
usd_setprimvarinterpolation Sets the interpolation of a primvar.
usd_setpurpose Sets the primitive’s purpose.
usd_setrelationshiptargets Sets the targets in the primitive’s relationship
usd_settransformorder Sets the primitive’s transform order
usd_settransformreset Sets/clears the primitive’s transform reset flag
usd_setvariantselection Sets the selected variant in the given variant set.
usd_setvisibility Configures the primitive to be visible, invisible, or to inherit visibility from the parent.
usd_setvisible Makes the primitive visible or invisible.
usd_specifier Returns the primitive’s specifier.
usd_transformname Constructs a full name of a transform operation
usd_transformorder Obtains the primitive’s transform order
usd_transformsuffix Extracts the transform operation suffix from the full name
usd_transformtype Infers the transform operation type from the full name
usd_typename Returns the name of the primitive’s type.
usd_uniquetransformname Constructs a unique full name of a transform operation
usd_variants Returns the variants belonging to the given variant set on a primitive.
usd_variantselection Returns the currently selected variant in a given variant set.
usd_variantsets Returns the variant sets available on a primitive.
usd_worldtransform Obtains the primitive’s world transform

Utility

utility_group

assert_enabled Returns 1 if the VEX assertions are enabled (see HOUDINI_VEX_ASSERT) or 0 if assertions are disabled. Used the implement the assert macro.
assign An efficient way of extracting the components of a vector or matrix into float variables.
error Reports a custom runtime VEX error.
forpoints
getcomp Extracts a single component of a vector type, matrix type, or array.
isbound Parameters in VEX can be overridden by geometry attributes (if the attributes exist on the surface being rendered).
isvarying Check whether a VEX variable is varying or uniform.
opend Ends a long operation.
opstart Start a long operation.
pack_inttosafefloat Reversibly packs an integer into a finite, non-denormal float.
print_once Prints a message only once, even in a loop.
printf Prints values to the console which started the VEX program.
ramp_lookup Evaluates a Houdini-style ramp at a specific location.
ramp_pack Packs a set of arrays into a string-encoded ramp.
ramp_unpack Unpacks a string-encoded ramp into a set of arrays.
select Returns one of two parameters based on a conditional.
set Creates a new value based on its arguments, such as creating a vector from its components.
setcomp Sets a single component of a vector or matrix type, or an item in an array.
sleep Yields processing for a certain number of milliseconds.
swizzle Rearranges the components of a vector.
unpack_intfromsafefloat Reverses the packing of pack_inttosafefloat to get back the original integer.
warning Reports a custom runtime VEX warning.

volume

volume_group

volume Returns the volume of the microvoxel containing a variable such as P.
volumecubicsample Samples the volume primitive’s value.
volumecubicsamplev Samples the volume primitive’s value.
volumegradient Calculates the volume primitive’s gradient.
volumeindex Gets the value of a specific voxel.
volumeindexactive Gets the active setting of a specific voxel.
volumeindexi Gets the integer value of a specific voxel.
volumeindexorigin Gets the index of the bottom left of a volume primitive.
volumeindexp Gets the vector4 value of a specific voxel.
volumeindextopos Converts a volume voxel index into a position.
volumeindexu Gets the vector2 value of a specific voxel.
volumeindexv Gets the vector value of a specific voxel.
volumepostoindex Converts a position into a volume voxel index.
volumeres Gets the resolution of a volume primitive.
volumesample Samples the volume primitive’s float value.
volumesamplei Samples the volume primitive’s integer value.
volumesamplep Samples the volume primitive’s vector4 value.
volumesampleu Samples the volume primitive’s vector2 value.
volumesamplev Samples the volume primitive’s vector value.
volumesmoothsample Samples the volume primitive’s value.
volumesmoothsamplev Samples the volume primitive’s value.
volumetypeid Gets the typeid of the data of a volume or VDB primitive.
volumevoxeldiameter Computes the approximate diameter of a voxel.

weightarray

weightarray_group

weightarrayblend Blends an existing name/weight array pair with another array or named item.
weightarrayfromname Initializes an index array and weight array pair with a single named entry.
weightarraynormalize Normalizes an array of floats so it sums to 1.0.
weightarraythreshold Discards any weights below a threshold from an name/weight array pair.