bvle-voxels/shaders/voxelSmoothPS.hlsl

// BVLE Voxels - Smooth Surface Nets Pixel Shader (Phase 5.1)
// Triplanar texture sampling + material blending + same lighting as voxel PS.

#include "voxelCommon.hlsli"

Texture2DArray<float4> materialTextures : register(t1);
SamplerState texSampler : register(s0);

struct PSInput {
    float4 position : SV_POSITION;
    float3 worldPos : WORLDPOS;
    float3 normal   : NORMAL;
    nointerpolation uint matPacked : MATERIALID;
};

// Sample triplanar texture for a given material index
float3 sampleTriplanar(float3 worldPos, float3 blend, float tiling, uint matIdx) {
    uint texIdx = clamp(matIdx - 1u, 0u, 5u);
    float4 xS = materialTextures.Sample(texSampler, float3(worldPos.yz * tiling, (float)texIdx));
    float4 yS = materialTextures.Sample(texSampler, float3(worldPos.xz * tiling, (float)texIdx));
    float4 zS = materialTextures.Sample(texSampler, float3(worldPos.xy * tiling, (float)texIdx));
    return xS.rgb * blend.x + yS.rgb * blend.y + zS.rgb * blend.z;
}

[RootSignature(VOXEL_ROOTSIG)]
float4 main(PSInput input) : SV_TARGET0 {
    float3 N = normalize(input.normal);
    float tiling = textureTiling;

    // Unpack materials: materialID(8) | secondaryMat(8) | blendWeight(8) | pad(8)
    uint primaryMat   = input.matPacked & 0xFF;
    uint secondaryMat = (input.matPacked >> 8) & 0xFF;
    float blendWeight = ((input.matPacked >> 16) & 0xFF) / 255.0;

    // Triplanar blend weights
    float3 blend = abs(N);
    blend = blend / (blend.x + blend.y + blend.z + 0.001);

    // Sample primary and secondary materials
    float3 primaryColor = sampleTriplanar(input.worldPos, blend, tiling, primaryMat);
    float3 texColor;
    if (blendWeight > 0.01 && secondaryMat != primaryMat) {
        float3 secondaryColor = sampleTriplanar(input.worldPos, blend, tiling, secondaryMat);
        texColor = lerp(primaryColor, secondaryColor, blendWeight);
    } else {
        texColor = primaryColor;
    }

    // Lighting (same model as voxel PS)
    float3 L = normalize(-sunDirection.xyz);
    float NdotL = max(dot(N, L), 0.0);

    float3 ambient = float3(0.15, 0.18, 0.25);
    float3 lit = texColor * (sunColor.rgb * NdotL + ambient);

    return float4(lit, 1.0);
}