[require] GLSL >= 1.10 [vertex shader] void main() { if (gl_Vertex.x >= 30.0) gl_FrontColor = vec4(1.0, 0.0, 0.0, 0.0); else gl_FrontColor = vec4(0.0, 1.0, 0.0, 0.0); gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } [fragment shader file] glsl-color.frag [test] ortho clear color 0.5 0.5 0.5 0.5 clear draw rect 10 10 10 10 draw rect 30 10 10 10 probe rgb 15 15 0.0 1.0 0.0 probe rgb 35 15 1.0 0.0 0.0