verts.glsl

layout(location=0) in ivec3 in_p;
smooth out vec2 v_uv;//ints cant smooth
void main(){
	//instanced triangle fan
	const ivec2[] lxy= ivec2[](
		ivec2(-4,-4),
		ivec2(-4, 4),
		ivec2( 4, 4),
		ivec2( 4,-4)
	);
	gl_Position= project( //project is mapping function onto screenspace, ie view matrix
		in_p.xy*8 + lxy[gl_VertexID],
		in_p.z);
	const vec2[] luv= vec2[](
		ivec2( 0, 0),
		ivec2( 0, 8),
		ivec2( 8, 8),
		ivec2( 8, 0)
	);
	v_uv= luv[gl_VertexID];
}