scatter

Context(s)	displace fog light shadow surface

int  scatter(vector ipoint, vector inormal, vector idirection, vector idistribution, float time, float maxdist, vector &opoint, vector &onormal, vector &odirection)

Evaluates a single scattering event through geometry. A return value of 1 means the scattering was successful.

ipoint

Entry point of scattering.

inormal

Surface normal at the entry point (surfaces only). Required to orient the scattering plane.

idirection

Primary scattering direction at the entry point. Required to orient the scattering plane.

idistribution

Initial scatter distribution at the entry point. If a zero-valued vector is passed a random scatter distribution will be used.

maxdist

Maximum distance to scatter.

opoint

Exit point of scattering.

onormal

Normal at the scattering exit point (surfaces only).

odirection

Outgoing direction at the scattering exit point (surfaces only).

// Trace for intersection with scene
vector hitP = 0;
vector hitN = 0;
int hit = trace(P, I, Time, "P", hitP, "N", hitN);

// Scatter a random distance from the intersection
vector idistribution = 0;
int sid = israytrace ? SID : newsampler();
vector s;
nextsample(sid, s.x, s.y, "mode", "nextpixel");
float maxdist = 2.0 * s.x;
vector opoint = 0;
vector onormal = 0;
vector odirection = 0;
hit = scatter(hitP, hitN, I, idistribution, Time, maxdist, opoint, onormal, odirection);

// Trace again from the exit point of the scattering
hit = trace(opoint, odirection, Time, "P", hitP, "N", hitN);