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| Shader "Custom/URP/TriplanarMapping"
{
Properties
{
_MainTex ("Albedo Texture", 2D) = "white" {}
_NormalMap ("Normal Map", 2D) = "bump" {}
_NormalStrength ("Normal Strength", Range(0, 2)) = 1.0
_Tiling ("World Space Tiling", Float) = 1.0
_Blend ("Blend Sharpness", Range(1, 8)) = 4.0
_Smoothness ("Smoothness", Range(0, 1)) = 0.3
_Metallic ("Metallic", Range(0, 1)) = 0.0
}
SubShader
{
Tags
{
"RenderType" = "Opaque"
"RenderPipeline" = "UniversalPipeline"
"Queue" = "Geometry"
}
Pass
{
Tags { "LightMode" = "UniversalForward" }
HLSLPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile _ _MAIN_LIGHT_SHADOWS
#pragma multi_compile _ _MAIN_LIGHT_SHADOWS_CASCADE
#pragma multi_compile _ _SHADOWS_SOFT
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
struct Attributes
{
float4 positionOS : POSITION;
float3 normalOS : NORMAL;
float4 tangentOS : TANGENT;
};
struct Varyings
{
float4 positionHCS : SV_POSITION;
float3 positionWS : TEXCOORD0; // 世界空间位置（用于 triplanar 投影）
float3 normalWS : TEXCOORD1;
float3 tangentWS : TEXCOORD2;
float3 bitangentWS : TEXCOORD3;
};
TEXTURE2D(_MainTex); SAMPLER(sampler_MainTex);
TEXTURE2D(_NormalMap); SAMPLER(sampler_NormalMap);
CBUFFER_START(UnityPerMaterial)
float4 _MainTex_ST;
float _Tiling;
float _Blend;
float _NormalStrength;
float _Smoothness;
float _Metallic;
CBUFFER_END
Varyings vert(Attributes IN)
{
Varyings OUT;
VertexPositionInputs posInputs = GetVertexPositionInputs(IN.positionOS.xyz);
VertexNormalInputs norInputs = GetVertexNormalInputs(IN.normalOS, IN.tangentOS);
OUT.positionHCS = posInputs.positionCS;
OUT.positionWS = posInputs.positionWS;
OUT.normalWS = norInputs.normalWS;
OUT.tangentWS = norInputs.tangentWS;
OUT.bitangentWS = norInputs.bitangentWS;
return OUT;
}
// ===== Triplanar 采样核心函数 =====
// 返回三个轴方向的混合权重（已归一化）
float3 TriplanarWeights(float3 worldNormal, float blend)
{
float3 w = pow(abs(worldNormal), blend);
// 归一化，防止混合权重之和不为 1
return w / (w.x + w.y + w.z + 1e-6);
}
// 三面投影采样颜色纹理
half4 SampleTriplanar(TEXTURE2D_PARAM(tex, smp), float3 worldPos, float3 weights, float tiling)
{
// 三个轴的 UV（世界坐标直接用作纹理坐标）
half4 xProj = SAMPLE_TEXTURE2D(tex, smp, worldPos.zy * tiling); // YZ 面
half4 yProj = SAMPLE_TEXTURE2D(tex, smp, worldPos.xz * tiling); // XZ 面（地面）
half4 zProj = SAMPLE_TEXTURE2D(tex, smp, worldPos.xy * tiling); // XY 面
return xProj * weights.x + yProj * weights.y + zProj * weights.z;
}
// 三面投影采样法线贴图（需要在各轴的切线空间中重建法线）
float3 SampleTriplanarNormal(TEXTURE2D_PARAM(tex, smp),
float3 worldPos, float3 worldNormal,
float3 weights, float tiling, float strength)
{
// 分别采样三个面的法线
half4 xN = SAMPLE_TEXTURE2D(tex, smp, worldPos.zy * tiling);
half4 yN = SAMPLE_TEXTURE2D(tex, smp, worldPos.xz * tiling);
half4 zN = SAMPLE_TEXTURE2D(tex, smp, worldPos.xy * tiling);
// 解包法线（DXT5nm 格式：.ag 通道，或标准 .rgb 格式）
float3 nX = UnpackNormal(xN);
float3 nY = UnpackNormal(yN);
float3 nZ = UnpackNormal(zN);
// 法线强度控制
nX.xy *= strength;
nY.xy *= strength;
nZ.xy *= strength;
// 各轴的法线变换到世界空间
// X 面：tangent=Z, bitangent=Y
// Y 面：tangent=X, bitangent=Z
// Z 面：tangent=X, bitangent=Y
float3 nXWS = float3(nX.z * sign(worldNormal.x), nX.y, nX.x * sign(worldNormal.x));
float3 nYWS = float3(nY.x, nY.z * sign(worldNormal.y), nY.y * sign(worldNormal.y));
float3 nZWS = float3(nZ.x, nZ.y, nZ.z * sign(worldNormal.z));
return normalize(nXWS * weights.x + nYWS * weights.y + nZWS * weights.z + worldNormal);
}
half4 frag(Varyings IN) : SV_Target
{
float3 worldNormal = normalize(IN.normalWS);
float3 weights = TriplanarWeights(worldNormal, _Blend);
// 三面投影采样颜色和法线
half4 albedo = SampleTriplanar(TEXTURE2D_ARGS(_MainTex, sampler_MainTex),
IN.positionWS, weights, _Tiling);
float3 normal = SampleTriplanarNormal(TEXTURE2D_ARGS(_NormalMap, sampler_NormalMap),
IN.positionWS, worldNormal, weights,
_Tiling, _NormalStrength);
// URP 标准光照
InputData inputData = (InputData)0;
inputData.positionWS = IN.positionWS;
inputData.normalWS = normal;
inputData.viewDirectionWS = GetWorldSpaceNormalizeViewDir(IN.positionWS);
inputData.shadowCoord = TransformWorldToShadowCoord(IN.positionWS);
SurfaceData surfaceData = (SurfaceData)0;
surfaceData.albedo = albedo.rgb;
surfaceData.alpha = 1.0;
surfaceData.smoothness = _Smoothness;
surfaceData.metallic = _Metallic;
surfaceData.normalTS = float3(0, 0, 1); // 法线已在世界空间处理
return UniversalFragmentPBR(inputData, surfaceData);
}
ENDHLSL
}
// 阴影投射 Pass（必须包含，否则物体不产生阴影）
UsePass "Universal Render Pipeline/Lit/ShadowCaster"
}
}
|