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osd_limitsurface

osd_limitsurface evaluates the point attribute in the geometry specified as a subdivision surface.

For vertex attributes, use osd_limitsurfacevertex.

int  osd_limitsurface(<geometry>geometry, string attrib_name, int patch_id, float u, float v, <type>&result)

int  osd_limitsurface(<geometry>geometry, string attrib_name, int patch_id, float u, float v, float &result[])

<geometry>

When running in the context of a node (such as a wrangle SOP), this argument can be an integer representing the input number (starting at 0) to read the geometry from.

Alternatively, the argument can be a string specifying a geometry file (for example, a .bgeo) to read from. When running inside Houdini, this can be an op:/path/to/sop reference.

&result

The computed attribute value is stored in the variable you pass to this argument. The type of the variable should match the type of the attribute you are reading.

Returns

1 if computing the attribute was successful, 0 if it failed.

Possible reasons for failure are:

  • The geometry contains no polygons or the topology can’t be converted using Open Subdiv
  • The attribute doesn’t exist on the input geometry.
  • The attribute size/type doesn’t match the VEX type of the result argument.

Examples

examples

Generate a point cloud on the limit surface of a subdivision mesh.

int npatches = osd_patchcount(file);
for (int patch = 0; patch < npatches; patch++)
{
    for (int v = 0; v < 100; v++)
    {
        vector P;
        if (osd_limitsurface(file, "P", patch, nrandom(), nrandom(), P))
        {
            int ptid = addpoint(geohandle, P);
        }
    }
}