18.104.22.168 Using several transparent objects makes them black?
"When I put several transparent objects one in front of another or inside another, POV-Ray calculates a
few of them, but the rest are completely black, no matter what transparency values I give."
Short answer: Try increasing the
max_trace_level value in the
global_settings block (the
default is 5).
Raytracing has a peculiar feature: It can calculate reflection and refraction. Each time a ray hits the surface of
an object, the program looks if this surface is reflective and/or refractive. If so, it shoots another ray from this
point to the appropriate direction.
Now, imagine we have a glass sphere. Glass reflects and refracts, so when the ray hits the sphere, two additional
rays are calculated, one outside the sphere (for the reflection) and one inside (for the refraction). Now the inside
ray will hit the sphere again, so two new rays are calculated, and so on and so on...
You can easily see that there must be a maximum number of reflections/refractions calculated, because otherwise
POV-Ray would calculate that one pixel forever.
This number can be set with the
max_trace_level option in the
global_settings block. The
default value is 5, which is enough for most scenes. Sometimes it is not enough (specially when there are lots of
semitransparent objects one over another) so you have to increase it.
So try something like: