[require]
GLSL >= 1.10

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

[fragment shader]
uniform vec4 color;
void main()
{
	gl_FragColor = (vec4(-1.0, 0.0, 0.0, 0.0) -
			(vec4(-0.5, 0.0, 0.0, 0.0) + color));
}

[test]
uniform vec4 color -0.5 -1.0 0.0 0.0
draw rect -1 -1 2 2
probe all rgba 0.0 1.0 0.0 0.0