#version 330

in vec2 texcoord;
uniform sampler2D tex;
uniform float opacity;

vec4 default_post_processing(vec4 c);

vec4 window_shader() {
	vec2 texsize = textureSize(tex, 0);
	vec4 color = texture2D(tex, texcoord / texsize, 0);

  color = vec4(vec3(0.2126 * color.r + 0.7152 * color.g + 0.0722 * color.b) * opacity, color.a * opacity);
  // color = vec4(0.0, color.g * opacity, 0.0, color.a * opacity);
  // color = vec4(color.r * opacity, 0.0, 0.0, color.a * opacity);

	return default_post_processing(color);
}