源码 / Ch20/AutoTerrain.shader
Ch20/AutoTerrain.shader
// 案例 20.4：按高度/坡度自动混合多层地表（草 → 砂石 → 岩石 → 雪），层间用高度混合 Shader "Cookbook/Ch20/AutoTerrain" { Properties { [NoScaleOffset] _GrassTex ("Grass (A=Height)", 2D) = "white" {} [NoScaleOffset] _SandTex ("Sand (A=Height)", 2D) = "white" {} [NoScaleOffset] _RockTex ("Rock (A=Height)", 2D) = "white" {} [NoScaleOffset][Normal] _RockNormal ("Rock Normal", 2D) = "bump" {} [NoScaleOffset] _SnowTex ("Snow (A=Height)", 2D) = "white" {} [NoScaleOffset] _NoiseTex ("Breakup Noise", 2D) = "gray" {} _Tiling ("Ground Tiling (1/m)", Float) = 0.35 _RockTiling ("Rock Tiling (1/m)", Float) = 0.2 _SandHeight ("Sand Below Height", Float) = -0.6 _SnowHeight ("Snow Above Height", Float) = 7 _HeightBand ("Height Transition (m)", Float) = 0.6 _RockSlope ("Rock Slope (1-N.y)", Range(0, 1)) = 0.3 _SlopeBand ("Slope Transition", Range(0.001, 0.5)) = 0.08 _NoiseAmp ("Noise Amount", Float) = 1.5 _BlendDepth ("Height Blend Depth", Range(0.01, 1)) = 0.15 [Toggle(_DEBUG_WEIGHTS)] _DebugWeights ("Debug Weights", Float) = 0 } SubShader { Tags { "RenderType"="Opaque" "RenderPipeline"="UniversalPipeline" "Queue"="Geometry" } HLSLINCLUDE #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl" CBUFFER_START(UnityPerMaterial) float _Tiling, _RockTiling; float _SandHeight, _SnowHeight, _HeightBand; half _RockSlope, _SlopeBand, _NoiseAmp, _BlendDepth; CBUFFER_END ENDHLSL Pass { Name "ForwardLit" Tags { "LightMode"="UniversalForwardOnly" } // 自定义表面混合，没有 GBuffer Pass：Deferred 下也走前向 HLSLPROGRAM #pragma vertex vert #pragma fragment frag #pragma shader_feature_local_fragment _DEBUG_WEIGHTS #pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN #pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS #pragma multi_compile_fragment _ _ADDITIONAL_LIGHT_SHADOWS #pragma multi_compile_fragment _ _SHADOWS_SOFT _SHADOWS_SOFT_LOW _SHADOWS_SOFT_MEDIUM _SHADOWS_SOFT_HIGH #pragma multi_compile _ _FORWARD_PLUS #pragma multi_compile_fog #pragma multi_compile_instancing #include "Assets/Cookbook/Ch20/TerrainCommon.hlsl" // 多张图共用一个采样器：移动端采样器数量有限（常见上限 16 个），地形 Shader 尤其要省 TEXTURE2D(_GrassTex); SAMPLER(sampler_GrassTex); TEXTURE2D(_SandTex); TEXTURE2D(_RockTex); TEXTURE2D(_RockNormal); TEXTURE2D(_SnowTex); TEXTURE2D(_NoiseTex); SAMPLER(sampler_NoiseTex); struct Attributes { float4 positionOS : POSITION; float3 normalOS : NORMAL; UNITY_VERTEX_INPUT_INSTANCE_ID }; struct Varyings { float4 positionCS : SV_POSITION; float3 positionWS : TEXCOORD0; half3 normalWS : TEXCOORD1; half fogFactor : TEXCOORD2; }; Varyings vert(Attributes v) { Varyings o; UNITY_SETUP_INSTANCE_ID(v); VertexPositionInputs p = GetVertexPositionInputs(v.positionOS.xyz); o.positionCS = p.positionCS; o.positionWS = p.positionWS; o.normalWS = TransformObjectToWorldNormal(v.normalOS); o.fogFactor = ComputeFogFactor(p.positionCS.z); return o; } half4 frag(Varyings i) : SV_Target { half3 n = normalize(i.normalWS); float3 pos = i.positionWS; // 低频噪声：打破“等高线”一样整齐的分界 half noise = SAMPLE_TEXTURE2D(_NoiseTex, sampler_NoiseTex, pos.xz * 0.04).r - 0.5; half h = pos.y + noise * _NoiseAmp; half slope = 1.0 - n.y; // 0 = 平地，1 = 垂直崖壁 // 平缓的层用顶视投影即可；岩石主要出现在陡坡，必须 Triplanar float2 uvTop = pos.xz * _Tiling; half4 grass = SAMPLE_TEXTURE2D(_GrassTex, sampler_GrassTex, uvTop); half4 sand = SAMPLE_TEXTURE2D(_SandTex, sampler_GrassTex, uvTop * 1.3); half4 snow = SAMPLE_TEXTURE2D(_SnowTex, sampler_GrassTex, uvTop * 0.5); float3 tw = TriplanarWeights(n, 8); TriplanarUV tuv = GetTriplanarUV(pos, n, _RockTiling); half4 rock = SampleTriplanar(TEXTURE2D_ARGS(_RockTex, sampler_GrassTex), tuv, tw); half3 rockN = TriplanarNormalWS(TEXTURE2D_ARGS(_RockNormal, sampler_GrassTex), tuv, tw, n, 1, 3); // 规则 → 遮罩（0..1） half sandMask = 1.0 - smoothstep(_SandHeight - _HeightBand, _SandHeight + _HeightBand, h); half rockMask = smoothstep(_RockSlope - _SlopeBand, _RockSlope + _SlopeBand, slope + noise * 0.25); // 按“从下往上铺”的顺序逐层叠：每层都和“已经铺好的结果”做一次高度混合 half4 c = grass; half3 nrm = n; half4 layerW = half4(1, 0, 0, 0); // 记录各层最终占比：草/砂/岩/雪（调试用） half t = HeightBlendWeight(c.a, sand.a, sandMask, _BlendDepth); c = lerp(c, sand, t); layerW = half4(layerW.xyz * (1 - t), 0); layerW.y += t; t = HeightBlendWeight(c.a, rock.a, rockMask, _BlendDepth); c = lerp(c, rock, t); nrm = normalize(lerp(nrm, rockN, t)); layerW.xyz *= (1 - t); layerW.z += t; // 雪：高于雪线，并且“细节法线”朝上的地方才积得住——岩石的凹坑与台面先白 half snowSlope = 1.0 - nrm.y; half snowMask = smoothstep(_SnowHeight - _HeightBand, _SnowHeight + _HeightBand, h) * (1.0 - smoothstep(0.35, 0.65, snowSlope)); t = HeightBlendWeight(c.a, snow.a, snowMask, _BlendDepth); c = lerp(c, snow, t); nrm = normalize(lerp(nrm, n, t * 0.6)); layerW *= (1 - t); layerW.w += t; #if defined(_DEBUG_WEIGHTS) half3 dbg = layerW.x * half3(0.2, 0.7, 0.15) + layerW.y * half3(0.95, 0.75, 0.2) + layerW.z * half3(0.75, 0.25, 0.2) + layerW.w * half3(1, 1, 1); return half4(dbg * (0.55 + 0.45 * saturate(dot(n, half3(0.3, 0.9, -0.3)))), 1); #endif half smoothness = dot(layerW, half4(0.12, 0.18, 0.28, 0.5)); return Ch20ShadePBR(pos, nrm, i.positionCS, c.rgb, 0, smoothness, 1, i.fogFactor); } ENDHLSL } Pass { Name "ShadowCaster" Tags { "LightMode"="ShadowCaster" } ZWrite On ZTest LEqual ColorMask 0 HLSLPROGRAM #pragma vertex Ch20ShadowVert #pragma fragment Ch20EmptyFrag #pragma multi_compile_instancing #pragma multi_compile_vertex _ _CASTING_PUNCTUAL_LIGHT_SHADOW #include "Assets/Cookbook/Ch20/ShadowDepthPasses.hlsl" ENDHLSL } Pass { Name "DepthOnly" Tags { "LightMode"="DepthOnly" } ZWrite On ColorMask R HLSLPROGRAM #pragma vertex Ch20DepthVert #pragma fragment Ch20EmptyFrag #pragma multi_compile_instancing #include "Assets/Cookbook/Ch20/ShadowDepthPasses.hlsl" ENDHLSL } Pass { Name "DepthNormals" Tags { "LightMode"="DepthNormals" } ZWrite On HLSLPROGRAM #pragma vertex Ch20DepthVert #pragma fragment Ch20DepthNormalsFrag #pragma multi_compile_instancing #include "Assets/Cookbook/Ch20/ShadowDepthPasses.hlsl" ENDHLSL } } }