Initial commit: Minecraft 光追着色器包（从零实现的 path tracing）

shaders/Lib/BasicFunctions/Sunlight_Shadow.glsl

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+// 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