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for(int j = 0; j < contribution->GetNumSpecularLobes(); ++j) {
    for(int i = 0; i < numSamples; ++i) {
       contribution->GetSpecularLobe(j)[i] *= RtColorRGB(1.0,0.0f,0.0f);
    }
}

for(int j = 0; j < contribution->GetNumDiffuseLobes(); ++j) {
    for(int i = 0; i < numSamples; ++i) {
       contribution->GetDiffuseLobe(j)[i] *= RtColorRGB(1.0,0.0f,0.0f);
    }
}

Instance Data

The optional instance data contains data generated by the plugin when it is first encountered in the RI stream. When For a detailed discussion of instance data, see lightweight instancing services.  When the CreateInstanceData routine is called, the plugin has access to the parameter list of the light filter and can create arbitrary data that is stored by the renderer and supplied as the instanceData pointer during filtering. This should be uniform data that can be accessed by multiple threads simultaneously.  Pre-processing the parameter list is an important performance optimization.  A light filter will be invoked for every surface-to-light interaction, and in a production-level shot there can be billions of these events.

As an example, below is the CreateInstanceData method for PxrLightFilterCombiner. Like bxdfs, light filters can be referenced in arguments to other light filters. To run multiple light filters, call EvalParam to get pointers to the upstream light filter and it's instance. These are stored and used later during filtering.

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