(This is on MacOSX)
On my 8600M, it seems like the values in my floating-point FBOs
are being clamped (I want them unclamped), both in fixed and
shader pipelines. As verification, I read back the buffers and
checked their values and those that are meant to be >1.0 are
stuck at 1.0. (I do use RGBA32F internal textures)
This list entry also contradicts my experience, saying you can
get unclamped behaviour (which is the default for FP32) on a
As a side question, isn’t glClampColorARB supposed to be part of
OpenGL 2.0? Why isn’t it implemented on OSX then?
Lastly, I quote the specs from:
- How does the clamping control affect the blending equation?
RESOLVED: For fixed-point color buffers, the inputs and the
result of the blending equation are clamped. For
floating-point color buffers, no clamping occurs.