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

shaders/Lib/RTWSM/SampleWarp.glsl

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+#include "/Lib/Settings.glsl"
+#include "/Lib/Utilities.glsl"
+// MinecraftPT — RTWSM SampleWarp
+// Samples the warp map to redistribute shadow map coordinates.
+
+#ifndef SAMPLE_WARP_GLSL
+uniform sampler2D rtwWarp1D;
+#define SAMPLE_WARP_GLSL
+
+// Warp curve sampling: rtwWarp1D is a RG16 texture, RTW_RESOLUTION x 2
+// Row 0: warp curve (cumulative importance), Row 1: inverse warp curve
+vec2 SampleWarp(float value){
+	vec2 coord = vec2(value * (RTW_RESOLUTION - 1.0) + 0.5, 0.5) / vec2(RTW_RESOLUTION, 2.0);
+	return textureLod(rtwWarp1D, coord, 0.0).rg;
+}
+
+// Smooth warp sampling with lerp
+vec2 SampleRTWWarpSmooth(vec2 shadowScreenPos){
+	// The warp is 1D along the shadow map's X axis (sun direction)
+	float u = saturate(shadowScreenPos.x);
+
+	// Sample warp curve
+	vec2 warp = SampleWarp(u);
+
+	// Apply warp: remap x based on cumulative importance
+	float warpedX = warp.x;
+
+	// Also apply to y for 2D warping (using second channel)
+	float warpedY = warp.y;
+
+	return vec2(warpedX - u, warpedY - shadowScreenPos.y);
+}
+
+// Full warp application for shadow map sampling
+vec2 WarpShadowCoord(vec2 shadowScreenPos){
+	float u = saturate(shadowScreenPos.x);
+	vec2 warp = SampleWarp(u);
+
+	vec2 warped = vec2(warp.x, warp.y);
+
+	// The warp curve maps [0,1] -> [0,1] cumulative
+	// Inverse: sample with the inverse curve
+	return warped;
+}
+
+// Unwarp (for reconstructing world positions)
+vec2 UnwarpShadowCoord(vec2 warpedCoord){
+	// Binary search on the warp curve (forward map)
+	float low = 0.0;
+	float high = 1.0;
+
+	for (int i = 0; i < 8; i++){
+		float mid = (low + high) * 0.5;
+		vec2 sample = SampleWarp(mid);
+		if (sample.x < warpedCoord.x){
+			low = mid;
+		}else{
+			high = mid;
+		}
+	}
+
+	return vec2((low + high) * 0.5, warpedCoord.y);
+}
+
+#endif