[require]
GLSL >= 1.10

[vertex shader]
varying vec4 var;
void main()
{
	gl_Position = gl_Vertex;
	var = gl_Vertex.x * vec4(2, 4, 3, 1) * 20.0;
}

[fragment shader]
uniform vec4 arg0;
varying vec4 var;
void main()
{
	gl_FragColor = dFdx(var.ywxz);
}

[test]
draw rect -1 -1 2 2
probe rgba 1 1 0.64 0.16 0.32 0.48