[osg-users] osg_Vertex with GL compatibility profile

[Ravi Mathur]

Hi all,

I see some behavior that I don't understand when using the osg_Vertex shader attribute across various graphics cards. Hopefully someone can shed some light.

I am enabling OSG uniforms using GraphicsWindow->getState()->setUseModelViewAndProjectionUniforms(true). Then, in my vertex shader, I use osg_ProjectionMatrix and osg_Vertex. Note that I don't call State::setUseVertexAttributeAliasing().

Everything works fine on many graphics cards, but on some cards my vertex shader behaves as if osg_Vertex is undefined. It doesn't give any errors, just produces results as if the vertex is zero. This only seems to happen with graphics cards where the renderer reports "OpenGL 4.1 Compatibility Profile Context". Examples are ATI Radeon HD 5450 and AMD FirePro V5900 cards.

Any ideas on what I'm missing here? 

Thanks!
Ravi

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