Using both programmable and fixed pipeline functionality in OpenGL

问题

I have a vertex shader that transforms vertices to create a fisheye affect. Is is possible to just use just the vertex shader and use fixed pipeline for the fragment portion.

So basically i have an application that doesnt use shaders. I want to apply a fisheye affect using a vertex shader to transform all vertices, and then leave it to the application to take care to lighting, texturing, etc?

If this is not possible, is it possible to get a fisheye affect by messing with the contents of the gl back buffer?

Thanks

回答1:

If your code is on fixed function, then what you described is a problem - that's why having your graphics code in shaders is good: they let you change anything easily. Remember to use them in your next project. :)

OK, but for this particular I assume that you don't want to rewrite your whole rendering from scratch to shaders now...

You mentioned you want to have a "fisheye effect". Seems like you're lucky, because I believe you don't need shaders for that effect! If we're talking about the same effect, then you can achieve it just by replacing the GL_PROJECTION matrix from OpenGL's fixed function to a perspective matrix with a wider angle of vision.

回答2:

Yes, it's possible, altough some cards (notably ATI) don't support using a vertex shader without a fragment shader.

来源：https://stackoverflow.com/questions/4246143/using-both-programmable-and-fixed-pipeline-functionality-in-opengl