indirectLight property
Strength of one-bounce screen-space indirect light gathered along the
occlusion march, 0.0 (the default) disabling it. Radiance from the
previous frame's scene color is credited to each newly visible sector,
so lit surfaces bleed their color onto neighbors. Requires
AmbientOcclusionMethod.groundTruth with visibilityBitmask; while
active the chain renders in half-float and the sun's contact shadows
are unavailable (the channels carry radiance instead).
TODO(ssgi-reprojection): the radiance is sampled unreprojected, so fast
camera motion drags the bounce by one frame.
Implementation
double indirectLight = 0.0;