//===========================================================================
//
// Calculate light
//
// It is important to note that the light color is not desaturated
// due to ZDoom's implementation weirdness. Everything that's added
// on top of it, e.g. dynamic lights and glows are, though, because
// the objects emitting these lights are also.
//
// This is making this a bit more complicated than it needs to
// because we can't just desaturate the final fragment color.
//
//===========================================================================

vec4 getLightColor(float fogdist, float fogfactor)
{
	vec4 color = vColor;

	if (uLightLevel >= 0.0)
	{
		float newlightlevel = 1.0 - R_DoomLightingEquation(uLightLevel, gl_FragCoord.z);
		color.rgb *= newlightlevel;
	}
	else if (uFogEnabled > 0.0)
	{
		// brightening around the player for light mode 2
		if (fogdist < uLightDist)
		{
			color.rgb *= uLightFactor - (fogdist / uLightDist) * (uLightFactor - 1.0);
		}

		//
		// apply light diminishing through fog equation
		//
		color.rgb = mix(vec3(0.0, 0.0, 0.0), color.rgb, fogfactor);
	}

	//
	// handle glowing walls
	//
	if (uGlowTopColor.a > 0.0 && glowdist.x < uGlowTopColor.a)
	{
		color.rgb += desaturate(uGlowTopColor * (1.0 - glowdist.x / uGlowTopColor.a)).rgb;
	}
	if (uGlowBottomColor.a > 0.0 && glowdist.y < uGlowBottomColor.a)
	{
		color.rgb += desaturate(uGlowBottomColor * (1.0 - glowdist.y / uGlowBottomColor.a)).rgb;
	}
	color = min(color, 1.0);

	//
	// apply brightmaps (or other light manipulation by custom shaders.
	//
	color = ProcessLight(color);

	//
	// apply dynamic lights (except additive)
	//

	vec4 dynlight = uDynLightColor;

	if (uLightIndex >= 0)
	{
		ivec4 lightRange = ivec4(lights[uLightIndex]) + ivec4(uLightIndex + 1);
		if (lightRange.z > lightRange.x)
		{
			//
			// modulated lights
			//
			for(int i=lightRange.x; i<lightRange.y; i+=2)
			{
				vec4 lightpos = lights[i];
				vec4 lightcolor = lights[i+1];

				lightcolor.rgb *= max(lightpos.w - distance(pixelpos.xyz, lightpos.xyz),0.0) / lightpos.w;
				dynlight.rgb += lightcolor.rgb;
			}
			//
			// subtractive lights
			//
			for(int i=lightRange.y; i<lightRange.z; i+=2)
			{
				vec4 lightpos = lights[i];
				vec4 lightcolor = lights[i+1];

				lightcolor.rgb *= max(lightpos.w - distance(pixelpos.xyz, lightpos.xyz),0.0) / lightpos.w;
				dynlight.rgb -= lightcolor.rgb;
			}
		}
	}
	color.rgb = clamp(color.rgb + desaturate(dynlight).rgb, 0.0, 1.4);

	// prevent any unintentional messing around with the alpha.
	return vec4(color.rgb, vColor.a);
}