I am wondering if somebody can help.
I’ve got a list of quads, few of them got a flag and in the pixel shader I need to be able
to colour the quad with a flag half red and half black (just two random colors).
Probably when I render I need to understand when I am in the middle of my quad
but I don’t know how to do it.
You don’t need a texture if you only have two clearly defined colors. And you can define the coords yourself quite easily: You’ve got quads - made up of four vertices. That’s all you need to know. Define the coordinates, put them in the VBO and use the texture coordinates to decide how to color the quad.