GLSL Is Hard – Stop Using Operators and Love the V_vTexcoord
sailbound.blogspot.comVertex shaders do not process pixels. They take model vertices and their attributes as input. The vertex shader outputs transformed vertices which are eventually arranged into primitives (e.g., triangles). These primitives are later rasterized downstream and the resulting fragments (pixels and attributes) are passed to the fragment shader.
(The blog post was written by me, posted here by a friend.)
I updated the post to reflect that correction. I'm not super great with GLSL / shaders / understanding it in general, so thanks for the correction!