// MinecraftPT — Sunlight & Shadow
// Direct sunlight with RTWSM warped shadow map sampling and voxel shadow tracing.

#ifndef SUNLIGHT_SHADOW_GLSL
#define SUNLIGHT_SHADOW_GLSL

#include "/Lib/RTWSM/SampleWarp.glsl"
#include "/Lib/BasicFunctions/LightingConstants.glsl"

// Sample the warped shadow map
float SampleShadowMap(vec3 shadowPos){
	vec2 shadowCoord = shadowPos.xy * 0.5 + 0.5;
	vec3 shadowUv = vec3(UnshiftShadowScreenPos(shadowCoord), shadowPos.z * 0.5 + 0.5);

	float shadow = 0.0;
	float depth = shadowUv.z;

	#ifdef SHADOW_QUALITY
		#if SHADOW_QUALITY >= 2
			// 3x3 PCF
			for (int i = -1; i <= 1; i++){
			for (int j = -1; j <= 1; j++){
				vec2 sampleCoord = shadowUv.xy + vec2(i, j) * shadowPixelSize;
				shadow += step(texelFetch(shadowcolor0, ivec2(sampleCoord * shadowSize), 0).a, depth) * (1.0 / 9.0);
			}}
		#else
			shadow = step(texelFetch(shadowcolor0, ivec2(shadowUv.xy * shadowSize), 0).a, depth);
		#endif
	#else
		shadow = step(texelFetch(shadowcolor0, ivec2(shadowUv.xy * shadowSize), 0).a, depth);
	#endif

	return shadow;
}

// Full sunlight evaluation: shadow map + optional voxel shadow tracing
float GetSunShadow(vec3 viewPos, vec3 worldPos, vec3 vertexNormal, float lightmap){
	float shadow = 1.0;

	#ifdef PT_SHADOW
		vec3 shadowDir = normalize(shadowModelViewInverse2);
		shadow = ShadowTracing(viewPos, worldPos, vertexNormal, shadowDir, lightmap);
	#else
		// Shadow map path
		vec4 shadowPos = shadowProjection * shadowModelView * vec4(worldPos, 1.0);
		if (shadowPos.w > 0.0){
			vec3 shadowNdc = shadowPos.xyz / shadowPos.w;
			if (all(lessThan(abs(shadowNdc.xy), vec2(1.0)))){
				shadow = SampleShadowMap(shadowNdc);
			}
		}
	#endif

	return shadow;
}

// Direct sun light for a surface
vec3 GetSunlight(vec3 viewPos, vec3 worldPos, vec3 vertexNormal, vec3 worldNormal, float lightmap){
	float shadow = GetSunShadow(viewPos, worldPos, vertexNormal, lightmap);
	float NdotL = max(dot(worldNormal, GetSunDirWorld()), 0.0);

	vec3 sunColor = GetSunIrradiance();
	#ifdef COLORED_SHADOWS
		// Sample shadow albedo for colored shadows (subtle)
		vec3 shadowAlbedo = vec3(0.0);
		sunColor *= 1.0 - shadowAlbedo * 0.3;
	#endif

	return sunColor * shadow * NdotL;
}

#endif