feat: triplanar projected materials

package/Shaders/Common/Triplanar.hlsli

@@ -0,0 +1,62 @@
+#ifndef TRIPLANAR_HLSLI
+#define TRIPLANAR_HLSLI
+
+namespace Triplanar
+{
+	static const float BLEND_SHARPNESS = 6.0;  // Power for weight computation; higher = sharper axis transitions
+	static const float STRETCH_CUTOFF = 0.4;   // ~cos(66°) — per-axis alignment below this produces visible stretching
+
+	/// Compute triplanar blend weights using face normal mask and smooth vertex normal blend.
+	float3 GetWeights(float3 vertexNormal, float3 faceNormal, float sharpness = BLEND_SHARPNESS)
+	{
+		float3 mask = step(STRETCH_CUTOFF, abs(faceNormal));
+		float3 w = pow(abs(vertexNormal), sharpness) * mask;
+		return w / (dot(w, 1.0) + EPSILON_DIVISION);
+	}
+
+	/// Weighted triplanar sample blending all 3 planes — stable for alpha/fade values.
+	float4 Sample(Texture2D<float4> tex, SamplerState samp, float3 worldPos, float3 weights, float scale)
+	{
+		return tex.Sample(samp, worldPos.yz * scale) * weights.x +
+		       tex.Sample(samp, worldPos.xz * scale) * weights.y +
+		       tex.Sample(samp, worldPos.xy * scale) * weights.z;
+	}
+
+	/// Compute gradients for stochastic triplanar sampling, pre-computed before branching.
+	void ComputeGradients(float3 worldPos, float scale, out float3 dPdx, out float3 dPdy)
+	{
+		dPdx = ddx(worldPos * scale);
+		dPdy = ddy(worldPos * scale);
+	}
+
+	/// Stochastic triplanar: select one projection plane via noise, reducing 3 texture reads to 1.
+	float4 SampleStochastic(Texture2D<float4> tex, SamplerState samp, float3 worldPos, float3 weights, float scale, float noise)
+	{
+		float3 dPdx, dPdy;
+		ComputeGradients(worldPos, scale, dPdx, dPdy);
+
+		if (noise < weights.x)
+			return tex.SampleGrad(samp, worldPos.yz * scale, dPdx.yz, dPdy.yz);
+		if (noise < weights.x + weights.y)
+			return tex.SampleGrad(samp, worldPos.xz * scale, dPdx.xz, dPdy.xz);
+		return tex.SampleGrad(samp, worldPos.xy * scale, dPdx.xy, dPdy.xy);
+	}
+
+	/// Stochastic triplanar with mip bias via gradient scaling.
+	float4 SampleStochasticBias(Texture2D<float4> tex, SamplerState samp, float3 worldPos, float3 weights, float scale, float bias, float noise)
+	{
+		float3 dPdx, dPdy;
+		ComputeGradients(worldPos, scale, dPdx, dPdy);
+		float biasScale = exp2(bias);
+		dPdx *= biasScale;
+		dPdy *= biasScale;
+
+		if (noise < weights.x)
+			return tex.SampleGrad(samp, worldPos.yz * scale, dPdx.yz, dPdy.yz);
+		if (noise < weights.x + weights.y)
+			return tex.SampleGrad(samp, worldPos.xz * scale, dPdx.xz, dPdy.xz);
+		return tex.SampleGrad(samp, worldPos.xy * scale, dPdx.xy, dPdy.xy);
+	}
+}
+
+#endif  // TRIPLANAR_HLSLI

package/Shaders/Lighting.hlsl

@@ -10,6 +10,7 @@
 #include "Common/Random.hlsli"
 #include "Common/SharedData.hlsli"
 #include "Common/Skinned.hlsli"
+#include "Common/Triplanar.hlsli"
 
 #if defined(FACEGEN) || defined(FACEGEN_RGB_TINT)
 #	define SKIN
@@ -1977,8 +1978,10 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
 	float projWeight = 0;
 
 #	if defined(PROJECTED_UV)
-	float2 projNoiseUv = ProjectedUVParams.zz * input.TexCoord0.zw;
-	float projNoise = TexCharacterLightProjNoiseSampler.Sample(SampCharacterLightProjNoiseSampler, projNoiseUv).x;
+	float3 projWorldPos = input.WorldPosition.xyz + FrameBuffer::CameraPosAdjust[eyeIndex].xyz;
+	float3 triFaceNormal = normalize(-cross(ddx(input.WorldPosition.xyz), ddy(input.WorldPosition.xyz)));
+	float3 triWeights = Triplanar::GetWeights(tbnTr[2], triFaceNormal);
+	float projNoise = Triplanar::Sample(TexCharacterLightProjNoiseSampler, SampCharacterLightProjNoiseSampler, projWorldPos, triWeights, ProjectedUVParams.z).x;
 	float3 texProj = normalize(input.TexProj);
 #		if defined(TREE_ANIM) || defined(LODOBJECTSHD)
 	float vertexAlpha = 1;
@@ -1993,18 +1996,20 @@ PS_OUTPUT main(PS_INPUT input, bool frontFace : SV_IsFrontFace)
 	if (projWeight < 0)
 		discard;
 
+	rawBaseColor = Triplanar::SampleStochasticBias(TexColorSampler, SampColorSampler, projWorldPos, triWeights, ProjectedUVParams2.y, SharedData::MipBias, screenNoise);
+	baseColor = float4(Color::Diffuse(rawBaseColor.rgb), rawBaseColor.a);
 	worldNormal.xyz = projectedNormal;
 #			if defined(SNOW)
 	psout.Parameters.y = 1;
 #			endif  // SNOW
 #		elif !defined(FACEGEN) && !defined(MULTI_LAYER_PARALLAX) && !defined(PARALLAX) && !defined(SPARKLE)
 	if (ProjectedUVParams3.w > 0.5) {
-		float2 projNormalDiffuseUv = ProjectedUVParams3.x * projNoiseUv;
-		float3 projNormal = TransformNormal(TexProjNormalSampler.Sample(SampProjNormalSampler, projNormalDiffuseUv).xyz);
-		float2 projDetailNormalUv = ProjectedUVParams3.y * projNoiseUv;
-		float3 projDetailNormal = TexProjDetail.Sample(SampProjDetailSampler, projDetailNormalUv).xyz;
+		float diffuseNormalScale = ProjectedUVParams3.x * ProjectedUVParams.z;
+		float3 projNormal = TransformNormal(Triplanar::SampleStochastic(TexProjNormalSampler, SampProjNormalSampler, projWorldPos, triWeights, diffuseNormalScale, screenNoise).xyz);
+		float detailNormalScale = ProjectedUVParams3.y * ProjectedUVParams.z;
+		float3 projDetailNormal = Triplanar::SampleStochastic(TexProjDetail, SampProjDetailSampler, projWorldPos, triWeights, detailNormalScale, screenNoise).xyz;
 		float3 finalProjNormal = normalize(TransformNormal(projDetailNormal) * float3(1, 1, projNormal.z) + float3(projNormal.xy, 0));
-		float3 projBaseColor = Color::ColorToLinear(TexProjDiffuseSampler.Sample(SampProjDiffuseSampler, projNormalDiffuseUv).xyz) * Color::ColorToLinear(ProjectedUVParams2.xyz);
+		float3 projBaseColor = Color::ColorToLinear(Triplanar::SampleStochastic(TexProjDiffuseSampler, SampProjDiffuseSampler, projWorldPos, triWeights, diffuseNormalScale, screenNoise).xyz) * Color::ColorToLinear(ProjectedUVParams2.xyz);
 		projectedMaterialWeight = smoothstep(0, 1, 5 * (0.1 + projWeight));
 #			if defined(TRUE_PBR)
 		projBaseColor = saturate(EnvmapData.xyz * projBaseColor);