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

shaders/Lib/IndividualFunctions/CloudShadow.glsl

@@ -0,0 +1,28 @@
+#include "/Lib/Settings.glsl"
+#include "/Lib/Utilities.glsl"
+#include "/Lib/BasicFunctions/LightingConstants.glsl"
+// MinecraftPT — Cloud Shadow
+// Cloud shadow projection onto the ground from the cloud layer.
+
+#ifndef CLOUD_SHADOW_GLSL
+uniform sampler3D CloudNoise3D;
+#define CLOUD_SHADOW_GLSL
+
+float GetCloudShadow(vec3 worldPos){
+	float cloudAlt = mix(CLOUD_CLEAR_ALTITUDE, CLOUD_RAIN_ALTITUDE, wetness);
+	float cloudDensity = mix(CLOUD_CLEAR_DENSITY, CLOUD_RAIN_DENSITY, wetness);
+
+	// Project ground position onto cloud layer
+	vec3 shadowDir = normalize(GetSunDirWorld());
+	vec3 cloudPos = worldPos + shadowDir * (cloudAlt - worldPos.y) / shadowDir.y;
+
+	// Sample cloud density at that position
+	vec2 p = cloudPos.xz * CLOUD_BASE_NOISE_SCALE + frameTimeCounter * 0.001 * CLOUD_SPEED;
+	float n = textureLod(CloudNoise3D, vec3(p, 0.2), 0.0).r;
+
+	float shadow = 1.0 - saturate((n - 0.5) * cloudDensity * 2.0 * CLOUD_SHADOW);
+
+	return shadow;
+}
+
+#endif