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split_bsdf

void  split_bsdf(bsdf &lobes[], bsdf source, float &weights[])

void  split_bsdf(bsdf &lobes[], bsdf source, float &weights[], int mask)

void  split_bsdf(bsdf &lobes[], bsdf source, float &weights[], int mask, int type)

void  split_bsdf(bsdf &lobes[], bsdf source, float &weights[], int mask, int type, float u)

void  split_bsdf(bsdf &lobes[], bsdf source, float &weights[], int mask, int type, float u, float cdf[])

&lobes

The function overwrites this array with the BSDFs for the component lobes.

source

The BSDF to split.

weights

The function fills this array with the weights for the split lobes (same length as the returned bsdf array). When you sample Illumination using the returned lobes you must scale it by these weights.

mask

A bitmask indicating which types of bounces to evaluate.

See bouncemask for information on component label bitmasks.

type

How to split the lobes. You can #import "pbr.h" to get constant values representing the different split types:

  • PBR_SPLIT_FULL = 0
  • PBR_SPLIT_RANDOM = 1
  • PBR_SPLIT_ALBEDO = 2
  • PBR_SPLIT_COMPONENT = 3
  • PBR_SPLIT_DEFAULT = PBR_SPLIT_ALBEDO

u

Random value to sample the CDF at.

cdf

CDF used to control sampling among components of the BSDF.

Returns

An array of bsdf objects representing the lobes.

Examples

examples

// Split BSDF into component lobes
float weights[];
bsdf lobes[];
split_bsdf(lobes, hitF, weights);


// Get albedos of lobes
float albedos[];
resize(albedos, len(lobes));
for (int i = 0; i < len(lobes); i++)
{
    albedos[i] = luminance(albedo(lobes[i], -hitnI)) * weights[i];
}


// Compute CDF
float cdf[] = compute_cdf(albedos);


// Randomly select a BSDF based on albedo distribution
int index = 0;
sample_cdf(cdf, s.x, index);


// Do something with the selected BSDF
// lobes[index] ...