gl_PointSize and FBO - driver bug?

[flamz]

I've got a shader that renders particles using point sprites. I assign each sprite a size in the vertex shader by doing gl_PointSize = somevalue.

Everything runs well in a normal context, but when I use the same shader when rendering to an FBO, gl_PointSize is clamped to the 1...64 range (regardless of what I pass to glPointParameter (GL_POINT_SIZE_MAX).

Am I missing something?
Could this be a driver bug?

[tamlin]

Checked point sprite max?

My 7600 driver (AFAIK latest "stable" nvidia supplied to NT5 - 93.71) reports (using glview - the OpenGL extensions viewer) "Point size range: 1 to 63.75" (in 0.125 increments).

[MooZBlockoS]

It's not a driver bug.
If you have enabled both GL_POINT_SPRITE and GL_VERTEX_PROGRAM_POINT_SIZE, the point size is clamped to the implementation dependent point size range (Section 3.3 in the 2.1 spec).

You'll have to disable GL_POINT_SPRITE and enable GL_VERTEX_PROGRAM_POINT_SIZE to avoid any clamping.