Pixel-Composer/shaders/sh_invert_all/sh_invert_all.fsh

//
// Simple passthrough fragment shader
//
varying vec2 v_vTexcoord;
varying vec4 v_vColour;

void main() {
	vec4 c = texture2D( gm_BaseTexture, v_vTexcoord );
    gl_FragColor = 1. - c;
}