Ambient Gain Formula

This function converts raytracing energy values to ambient gain values.

The AmbientGainFormula is invoked twice per emitter:

• Once with low-frequency energy values
• Once with high-frequency energy values

The default formula specifies that 10% of occlusion energy, or 10% of permeation energy is required for ambient sounds to be at max volume:

emitter.AmbientGainFormula = (
    bool lowFrequency,
    int occlusionRayCount,
    int permeationRayCount,
    int permeationBounceCount,
    float occlusionEnergy,
    float permeationEnergy)
{
    float gain = 0.0f;

    if (occlusionRayCount > 0)
    {
        // 10% energy required to be at max volume
        float rayThreshold = 0.1f * occlusionRayCount;
        gain += occlusionEnergy / rayThreshold;
    }

    if (permeationRayCount > 0 && permeationBounceCount > 0)
    {
        // 10% energy required to be at max volume
        float rayThreshold = 0.1f * (permeationRayCount * permeationBounceCount);
        gain += permeationEnergy / rayThreshold;
    }

    return MathF.Min(1, gain);
}

Parameters:

• lowFrequency - indicates whether AmbientGainFormula is invoked with low-frequency energy values or high-frequency energy values (AmbientGainFormula is invoked twice)
• occlusionRayCount is the number of occlusion rays that were cast by the source emitter
• permeationRayCount is the number of permeation rays that were cast by the source emitter
• permeationBounceCount is the number of bounces per permeation ray
• occlusionEnergy is in the range 0.0 to 1.0, where 1.0 means all occlusion rays reached the world edge with maximum energy remaining (i.e. no occlusion)
• permeationEnergy is in the range 0.0 to 1.0, where 1.0 means all permeation rays reached the world edge with maximum energy remaining (i.e. all rays passed through air)

The results of these functions are stored on the emitter.AmbientFilter object, which is null until raytracing has completed for the first time:

if (emitter.AmbientFilter != null)
{
    var gainLF = emitter.AmbientFilter.GainLF;
    var gainHF = emitter.AmbientFilter.GainHF;
}