On Feb 27, 2008, at 4:42 AM, Alex Drinkwater wrote:
I recently read somewhere GPUs generally do not implement branching
conditional properly, and will actually evaluate both cases, then
choose between the results.
Is this the case,
Frequently yes, by design, but sometimes no, it depends on the
hardware capabilities and whether the complexity of the branch caused
a fallback to software.
There's a few very descriptive posts about this on the mac-opengl
mailing list.
Search the archives for +"Nick Burns" +"conditional" http://search.lists.apple.com/
and if so, is there some way to force only certain parts of a GLSL
shader program to be executed?
No, aside from taking out the conditional.
Allan
___________
Allan Schaffer
Graphics Evangelist
Worldwide Developer Relations
