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

2026-09-19 12:06:22 +08:00
commit 59e30822f8
314 changed files with 9259 additions and 0 deletions
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+#include "/Lib/Settings.glsl"
+#include "/Lib/Utilities.glsl"
+// MinecraftPT — Specular Tracer
+// Traces GGX-sampled reflection/refraction rays through the voxel grid and
+// accumulates the reflected radiance (incl. light sphere contributions).
+
+#ifndef SPECULAR_TRACER_GLSL
+#define SPECULAR_TRACER_GLSL
+
+#include "/Lib/PathTracing/Tracer/TracingUtilities.glsl"
+#include "/Lib/BasicFunctions/LightingConstants.glsl"
+#include "/Lib/PathTracing/Tracer/ShadowTracing.glsl"
+#include "/Lib/PathTracing/Tracer/SampleIRC.glsl"
+
+	// Panorama: 3:2 cubemap cross. Map direction to face UV.
+	float absX = abs(dir.x), absY = abs(dir.y), absZ = abs(dir.z);
+	float maxAxis = max(absX, max(absY, absZ));
+
+	vec2 uv;
+	vec3 tdir = dir / maxAxis;
+
+	if (maxAxis == absX){
+		uv = vec2(tdir.y * 0.5 + 0.5, tdir.z * 0.5 + 0.5) / vec2(3.0, 2.0) + vec2(0.0, 0.5) * vec2(1.0/3.0, 1.0/2.0);
+		if (tdir.x > 0.0){
+			uv = vec2(tdir.y * 0.5 + 0.5, tdir.z * 0.5 + 0.5) / vec2(3.0, 2.0) + vec2(1.0/3.0, 0.5/2.0);
+		}
+	}else if (maxAxis == absY){
+		uv = vec2(tdir.x * 0.5 + 0.5, tdir.z * 0.5 + 0.5) / vec2(3.0, 2.0) + vec2(2.0/3.0, 0.5/2.0);
+		if (tdir.y > 0.0){
+			uv = vec2(tdir.x * 0.5 + 0.5, tdir.z * 0.5 + 0.5) / vec2(3.0, 2.0) + vec2(1.0/3.0, 0.5/2.0);
+		}
+	}else{
+		uv = vec2(tdir.x * 0.5 + 0.5, tdir.y * 0.5 + 0.5) / vec2(3.0, 2.0) + vec2(2.0/3.0, 1.5/2.0);
+		if (tdir.z > 0.0){
+			uv = vec2(tdir.x * 0.5 + 0.5, tdir.y * 0.5 + 0.5) / vec2(3.0, 2.0) + vec2(1.0/3.0, 1.5/2.0);
+		}
+	}
+
+	return textureLod(skyBox2D, uv, 0.0).rgb;
+}
+
+// Trace a single specular ray and accumulate radiance.
+// origin: world pos (voxel space handled inside), dir: normalized direction
+vec3 SpecularTrace(vec3 voxelPos, vec3 dir, float maxDist, vec2 noise){
+	vec3 result = vec3(0.0);
+
+	Ray ray = PackRay(voxelPos, dir);
+
+	vec3 voxelCoord = floor(ray.ori);
+	vec3 totalStep = (ray.sdir * (voxelCoord - ray.ori + 0.5) + 0.5) * abs(ray.rdir);
+	float rayLength = 0.0;
+	vec3 tracingNext;
+
+	bool hit = false;
+
+	for (int i = 0; i < 128; i++){
+		if (clamp(voxelCoord, vec3(0.0), vec3(voxelResolution - 0.5)) != voxelCoord){
+			// Escaped the voxel grid — sample sky
+			result = SampleSkyBox(dir);
+			break;
+		}
+
+		if (rayLength > maxDist){
+			result = SampleSkyBox(dir);
+			break;
+		}
+
+		vec4 voxelData = texelFetch(voxelData3D, ivec3(voxelCoord), 0);
+		float voxelID = DecodeVoxelID(voxelData.z);
+
+		// Light source: accumulate sphere light
+		if (IsLightSphere(voxelID)){
+			result += HitLightShpereReflection(ray, voxelCoord, voxelID, rayLength);
+			rayLength = minVec3(totalStep);
+			tracingNext = step(totalStep, vec3(rayLength));
+			voxelCoord += tracingNext * ray.sdir;
+			totalStep += tracingNext * abs(ray.rdir);
+			continue;
+		}
+
+		if (voxelID >= 999.0){ // Full block
+			// Shade the hit point: sample albedo from atlas, apply lighting
+			vec3 hitPos = ray.ori + ray.dir * rayLength;
+			vec3 hitNormal = -step(vec3(rayLength), totalStep - abs(ray.rdir)) * ray.sdir;
+			vec2 midCoord = voxelData.xy;
+			vec3 albedo = SampleVoxelAlbedo(midCoord, hitPos, hitNormal);
+
+			// Direct light from sun
+			vec3 sunColor = GetSunIrradiance();
+			float sunShadow = SimpleShadowTracing(hitPos + hitNormal * 0.01, GetSunDirWorld());
+			vec3 direct = albedo * sunColor * sunShadow * max(dot(hitNormal, GetSunDirWorld()), 0.0);
+
+			// Sky ambient from IRC
+			vec3 irc = SampleIRC(hitPos);
+			result += direct + irc * albedo * 0.5;
+
+			hit = true;
+			break;
+		}else if (voxelID < 1000.0 && voxelID > 1.0){
+			// Cutout shape
+			float rawID = 1000.0 - voxelID;
+			rayLength = minVec3(totalStep);
+			vec3 n;
+			if (HitShape(ray, voxelCoord, rawID, rayLength, n)){
+				vec3 hitPos = ray.ori + ray.dir * rayLength;
+				vec2 midCoord = voxelData.xy;
+				vec3 albedo = SampleVoxelAlbedo(midCoord, hitPos, n);
+
+				vec3 sunColor = GetSunIrradiance();
+				float sunShadow = SimpleShadowTracing(hitPos + n * 0.01, GetSunDirWorld());
+				vec3 direct = albedo * sunColor * sunShadow * max(dot(n, GetSunDirWorld()), 0.0);
+
+				vec3 irc = SampleIRC(hitPos);
+				result += direct + irc * albedo * 0.5;
+
+				hit = true;
+				break;
+			}
+		}
+
+		// Sparse skip
+		float marker = voxelData.z;
+		if (marker > 0.60 && marker < 0.92){
+			float skipSize = marker > 0.90 ? 8.0 : (marker > 0.70 ? 4.0 : 2.0);
+			vec3 nextBoundary = floor((voxelCoord + 1.0) / skipSize) * skipSize;
+			vec3 distToBoundary = (nextBoundary - voxelCoord) * abs(ray.rdir);
+			float tSkip = minVec3(distToBoundary) + 1e-4;
+			rayLength += tSkip;
+			vec3 stepVec = ray.sdir * abs(ray.rdir) * tSkip;
+			ray.ori += stepVec;
+			voxelCoord = floor(ray.ori);
+			totalStep = (ray.sdir * (voxelCoord - ray.ori + 0.5) + 0.5) * abs(ray.rdir);
+			continue;
+		}
+
+		rayLength = minVec3(totalStep);
+		tracingNext = step(totalStep, vec3(rayLength));
+		voxelCoord += tracingNext * ray.sdir;
+		totalStep += tracingNext * abs(ray.rdir);
+	}
+
+	if (!hit){
+		result = SampleSkyBox(dir);
+	}
+
+	return result;
+}
+
+#endif