varying variables without vertex shader

OpenGL OpenGL: Advanced Coding
1

I’m wondering if it’s possible to pass a varying variable into a fragment shader without having to write a vertex shader to pass that variable along. I know how to pass information into gl_Color (a pre-defined variable). But I’d like to have a variable for normals in my fragment shader.

BTW: I don’t want to create a vertex shader because my understanding (from my own tests) is that vertex shaders can’t implement fixed functionality without serious performance costs (given my Intel graphics card/drivers).

2

As far as I know, GLSL spec tells that varying qualifier is only for communication between vertex and fragment shaders and do not make sense having varying variables only in fragment shader, I don’t even know if this compiles without errors.

For more information read this post

3

McLeary, thanks.