Precalculate the distance at which lights will fade to zero brightness.
For lights with inverse falloff, use the gate value to determine the
cut-off distance. Use this value to cull samples and avoid the ray
tracing overhead.
Hopefully not too controversially, I am going to default this to "on" with
a gate value of 0.001. Unless you have > 1000 lights contributing
fractional light values across your map, this is not going to make any
visible difference.
Signed-off-by: Kevin Shanahan <kmshanah@disenchant.net>
a8d8150791