Hey all,

I'm trying to play around with large points (32 by 32), yes, these are GL_POINTS, drawn with point size 32. First I want to experiment with Algorithmically drawing on these points in the fragment shader, and second I want to map textures onto these points (using the built-in variable gl_PointCoord in the fragment shader).

I'm not having any luck accessing the gl_PointCoord vector.

I've included the gl_PointCoord.s and gl_PointCoord.t in my shader, as color values, but nothing is the result..... I also tried x and y.

I've tried googling some examples of using this built-in variable, but no luck so far.

Anybody have some examples that work, that I could see? Or anyone know of a bug/reason why these won't work?

I'm trying to add to my videos on youtube that show how to program in OpenGL, here's the shameless link:


Thanks guys, appreciate any help you can throw my way,

Jeff Cummings