gzdoom/wadsrc/static/shaders/scene/lightmodel_default.glsl

#include "lightmodel_software.glsl"
#include "material.glsl"

vec4 ProcessLight(Material mat, vec4 color);

//===========================================================================
//
// 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(Material material)
{
	// calculate fog factor
	float fogdist = 0.0;
	float fogfactor = 0.0;
	if (uFogEnabled != 0)
	{
		if (uFogEnabled == 1 || uFogEnabled == -1) 
		{
			fogdist = max(16.0, pixelpos.w);
		}
		else 
		{
			fogdist = max(16.0, distance(pixelpos.xyz, uCameraPos.xyz));
		}
		fogfactor = exp2 (uFogDensity * fogdist);
	}

	vec4 color = vColor;

	if (uLightLevel >= 0.0)
	{
		float newlightlevel = 1.0 - R_DoomLightingEquation(uLightLevel);
		color.rgb *= newlightlevel;
	}
	else if (uFogEnabled > 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);

	// these cannot be safely applied by the legacy format where the implementation cannot guarantee that the values are set.
#if !defined LEGACY_USER_SHADER && !defined NO_LAYERS
	//
	// apply glow 
	//
	color.rgb = mix(color.rgb, material.Glow.rgb, material.Glow.a);

	//
	// apply brightmaps 
	//
	color.rgb = min(color.rgb + material.Bright.rgb, 1.0);
#endif

	//
	// apply other light manipulation by custom shaders, default is a NOP.
	//
	color = ProcessLight(material, color);

	//
	// apply lightmaps
	//
	if (vLightmap.z >= 0.0)
	{
		color.rgb += texture(LightMap, vLightmap).rgb;
	}

	//
	// apply dynamic lights
	//
	vec4 frag = vec4(ProcessMaterialLight(material, color.rgb), material.Base.a * vColor.a);

	//
	// colored fog
	//
	if (uFogEnabled < 0) 
	{
		frag = vec4(mix(uFogColor.rgb, frag.rgb, fogfactor), frag.a);
	}

	return frag;
}

// The color of the fragment if it is fully occluded by ambient lighting

vec3 AmbientOcclusionColor()
{
	float fogdist;
	float fogfactor;

	//
	// calculate fog factor
	//
	if (uFogEnabled == -1) 
	{
		fogdist = max(16.0, pixelpos.w);
	}
	else 
	{
		fogdist = max(16.0, distance(pixelpos.xyz, uCameraPos.xyz));
	}
	fogfactor = exp2 (uFogDensity * fogdist);

	return mix(uFogColor.rgb, vec3(0.0), fogfactor);
}