[require] GLSL >= 1.20 [vertex shader file] glsl-mvp.vert [fragment shader] #version 120 void main() { const float zero = asin(0.0); const float pi_over_three = asin(0.866025403784439); const float half_pi = asin(1.0); gl_FragColor = vec4(zero, pi_over_three - 1.0, half_pi - 1.0, 1.0); } [test] clear color 0.0 0.0 0.0 0.0 clear ortho draw rect 10 10 10 10 probe rgb 15 15 0.0 0.0471975511966 0.5707963267949