[require]
GLSL >= 1.10

[vertex shader]
varying vec2 pos;
void main()
{
	gl_Position = gl_Vertex;
	pos = gl_Vertex.xy;
}

[fragment shader]
varying vec2 pos;
const float pi = 3.14159265358979323846;
void main()
{
	/* Convert input value on [-1,1] to [-pi,pi] */
	float angle = pi * pos.x;

	float t = tan(angle);
	if (pos.y < -.667)
		gl_FragColor = vec4(vec3(pos.x / 2.0 + 0.5), 1.0);
	else if (pos.y < -.333) {
		float at = atan(t);
		gl_FragColor = vec4(vec3((at / (2.0 * pi)) + 0.5), 1.0);
	} else if (pos.y < 0.0) {
		float sgn = (abs(angle) > (pi / 2.0)) ? -1.0 : 1.0;
		float at = atan(sgn * t, sgn);

		gl_FragColor = vec4(vec3((at / (2.0 * pi)) + 0.5), 1.0);
	} else {
		gl_FragColor = vec4(vec3((t / 10.0) + 0.5), 1.0);
	}
}

[test]
draw rect -1 -1 2 2

# Everything in the first atan bar should give back the input value
relative probe rgb  (0.0, 0.4) (0.0, 0.0, 0.0)
relative probe rgb  (0.1, 0.4) (0.1, 0.1, 0.1)
relative probe rgb  (0.2, 0.4) (0.2, 0.2, 0.2)
relative probe rgb  (0.3, 0.4) (0.3, 0.3, 0.3)
relative probe rgb  (0.4, 0.4) (0.4, 0.4, 0.4)
relative probe rgb  (0.5, 0.4) (0.5, 0.5, 0.5)
relative probe rgb  (0.6, 0.4) (0.6, 0.6, 0.6)
relative probe rgb  (0.7, 0.4) (0.7, 0.7, 0.7)
relative probe rgb  (0.8, 0.4) (0.8, 0.8, 0.8)
relative probe rgb  (0.9, 0.4) (0.9, 0.9, 0.9)

# The portion of the second atan bar representing [-pi/2,pi/2] should be the
# same as the first atan bar.
relative probe rgb  (0.26, 0.2) (0.26, 0.26, 0.26)
relative probe rgb  (0.3, 0.2) (0.3, 0.3, 0.3)
relative probe rgb  (0.4, 0.2) (0.4, 0.4, 0.4)
relative probe rgb  (0.5, 0.2) (0.5, 0.5, 0.5)
relative probe rgb  (0.6, 0.2) (0.6, 0.6, 0.6)
relative probe rgb  (0.7, 0.2) (0.7, 0.7, 0.7)
relative probe rgb  (0.74, 0.2) (0.74, 0.74, 0.74)

relative probe rgb  (0.0, 0.2) (0.5, 0.5, 0.5)
relative probe rgb  (0.1, 0.2) (0.6, 0.6, 0.6)
relative probe rgb  (0.24, 0.2) (0.74, 0.74, 0.74)
relative probe rgb  (0.76, 0.2) (0.26, 0.26, 0.26)
relative probe rgb  (0.8, 0.2) (0.3, 0.3, 0.3)
relative probe rgb  (0.9, 0.2) (0.4, 0.4, 0.4)

# Sanity check by probing the input bar
relative probe rgb  (0.0, 0.1) (0.0, 0.0, 0.0)
relative probe rgb  (0.1, 0.1) (0.1, 0.1, 0.1)
relative probe rgb  (0.2, 0.1) (0.2, 0.2, 0.2)
relative probe rgb  (0.3, 0.1) (0.3, 0.3, 0.3)
relative probe rgb  (0.4, 0.1) (0.4, 0.4, 0.4)
relative probe rgb  (0.5, 0.1) (0.5, 0.5, 0.5)
relative probe rgb  (0.6, 0.1) (0.6, 0.6, 0.6)
relative probe rgb  (0.7, 0.1) (0.7, 0.7, 0.7)
relative probe rgb  (0.8, 0.1) (0.8, 0.8, 0.8)
relative probe rgb  (0.9, 0.1) (0.9, 0.9, 0.9)