This patch implements the Z Combine node for the realtime compositor.
The patch also extends the SMAA implementation to work with float
textures as a prerequisite to the Z Combine implementation. Moreover, a
mechanism for computing multi-output operations was implemented, in
which unneeded outputs will allocate a dummy 1x1 texture for a correct
shader invocation, then those dummy textures will be cleaned up by
calling a routine right after evaluation.
This is different from the CPU implementation in that the while combine
mask is anti-aliased, including the alpha mask, which is not considered
in the CPU case.
The node can be implemented as a GPU shader operation when the
anti-aliasing option is disabled, which is something we should do when
the evaluator allows nodes be executed as both standard and GPU shader
operations.
Pull Request: https://projects.blender.org/blender/blender/pulls/106637
b939b60c3f