Clamping in RGBA32F FBOs

Subject: Clamping in RGBA32F FBOs
From: Rex Guo <email@hidden>
Date: Tue, 28 Apr 2009 15:24:38 +0800
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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.

This list entry also contradicts my experience, saying you can get
unclamped behaviour (which is the default for FP32) on a 8600M:
http://lists.apple.com/archives/mac-opengl/2009/Mar/msg00044.html

As a side question, isn't glClampColorARB supposed to be part of
OpenGL 2.0?

Lastly, I quote the specs from:
http://oss.sgi.com/projects/ogl-sample/registry/ARB/color_buffer_float.txt

    3. 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.

TIA!

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