[require]
GLSL >= 1.20

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

[fragment shader]
void main() {
   const float dx = dFdx(0.0);
   const float dy = dFdy(0.0);
   const float fw = fwidth(0.0);
   if (dx == 0.0 && dy == 0.0 && fw == 0.0) {
      gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
   } else {
      gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
   }
}

[test]
draw rect -1 -1 2 2
probe all rgb 0.0 1.0 0.0