[require]
GLSL >= 1.20

[vertex shader]
void main()
{
	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}

[fragment shader]
void main() {
   const float zero = acos(1.0);
   const float half_pi = acos(0.0);
   const float pi = acos(-1.0);
   gl_FragColor = vec4(zero, half_pi - 1.0, pi - 3.0, 1.0);
}

[test]
draw rect -1 -1 2 2
probe all rgb 0.0 0.5707963267949 0.14159265358979