//modified version of [this shader](https://github.com/wessles/GLSL-CRT/blob/master/shader.frag)
const vec3 VIB_RGB_BALANCE = vec3(1.0, 1.0, 1.0);
const float VIB_VIBRANCE = 0.40;
const vec3 VIB_coeffVibrance = VIB_RGB_BALANCE * -VIB_VIBRANCE;

void windowShader(inout vec4 color) {
  vec2 texCoord = x_TexCoord;

	// Distance from the center
	float dx = abs(0.5-texCoord.x);
	float dy = abs(0.5-texCoord.y);

	// Square it to smooth the edges
	dx *= dx;
	dy *= dy;

	texCoord.x -= 0.5;
	texCoord.x *= 1.0 + (dy * 0.05);
	texCoord.x += 0.5;

	texCoord.y -= 0.5;
	texCoord.y *= 1.0 + (dx * 0.18);
	texCoord.y += 0.5;

	// Get texel, and add in scanline if need be
	color = x_Texture(texCoord);
	color.rgb += sin(texCoord.y * 1250.0) * 0.02;

	// Cutoff
	if(texCoord.y > 1.0 || texCoord.x < 0.0 || texCoord.x > 1.0 || texCoord.y < 0.0)
		color = vec4(0.0);

    // vec3 VIB_coefLuma = vec3(0.333333, 0.333334, 0.333333); // was for `if VIB_LUMA == 1`
    vec3 VIB_coefLuma = vec3(0.212656, 0.715158, 0.072186); // try both and see which one looks nicer.

    float luma = dot(VIB_coefLuma, color.rgb);

    float max_color = max(color.r, max(color.g, color.b));
    float min_color = min(color.r, min(color.g, color.b));

    float color_saturation = max_color - min_color;

    vec3 p_col = vec3(vec3(vec3(vec3(sign(VIB_coeffVibrance) * color_saturation) - 1.0) * VIB_coeffVibrance) + 1.0);

    color.r = mix(luma, color.r, p_col.r);
    color.g = mix(luma, color.g, p_col.g);
    color.b = mix(luma, color.b, p_col.b);
}