【URP】Unity[视差贴图]模拟[风格化地形]实践

URP HLSL完整实现代码

关键特性说明

• ‌动态层数优化‌：通过lerp(_MaxLayers, _MinLayers, saturate(dot(float3(0,0,1), viewDirTS)))实现平视视角自动增加采样精度

• ‌抗失真处理‌：_LayerBias参数修正陡峭表面的UV偏移计算，避免采样断裂

• ‌风格化增强‌：ramp贴图控制光影过渡，边缘光强化轮廓立体感

• StylizedRockParallax.shader

  	Shader "Universal Render Pipeline/StylizedRockParallax"
  	{
  	Properties
  	{
  	[Header(Base Textures)]
  	_MainTex("Albedo (RGB)", 2D) = "white" {}
  	_NormalMap("Normal Map", 2D) = "bump" {}
  	_HeightMap("Height Map", 2D) = "white" {}
  	_RampTex("Stylized Ramp", 2D) = "white" {}
  	[Header(Parallax Settings)]
  	_ParallaxScale("Depth Scale", Range(0, 0.15)) = 0.08
  	_LayerBias("Layer Bias", Range(0.1, 0.5)) = 0.3
  	_MinLayers("Min Layers", Int) = 5
  	_MaxLayers("Max Layers", Int) = 12
  	[Header(Stylized Lighting)]
  	_RimPower("Rim Power", Range(1, 10)) = 3
  	_ShadowTint("Shadow Tint", Color) = (0.3,0.3,0.4,1)
  	}
  	SubShader
  	{
  	Tags { "RenderType"="Opaque" "RenderPipeline"="UniversalPipeline" }
  	HLSLINCLUDE
  	#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
  	#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
  	TEXTURE2D(_MainTex); SAMPLER(sampler_MainTex);
  	TEXTURE2D(_NormalMap); SAMPLER(sampler_NormalMap);
  	TEXTURE2D(_HeightMap); SAMPLER(sampler_HeightMap);
  	TEXTURE2D(_RampTex); SAMPLER(sampler_RampTex);
  	float _ParallaxScale;
  	float _LayerBias;
  	int _MinLayers, _MaxLayers;
  	float _RimPower;
  	float4 _ShadowTint;
  	// 陡峭视差映射核心算法
  	float2 SteepParallaxMapping(float3 viewDirTS, float2 uv)
  	{
  	// 动态层数计算（平视视角增加层数）
  	int numLayers = (int)lerp(_MaxLayers, _MinLayers, saturate(dot(float3(0,0,1), viewDirTS)));
  	float layerHeight = 1.0 / numLayers;
  	float2 deltaUV = _ParallaxScale * viewDirTS.xy / (viewDirTS.z + _LayerBias) / numLayers;
  	// 光线步进初始化
  	float currentLayerHeight = 0;
  	float2 currentUV = uv;
  	float currentDepth = 1 - SAMPLE_TEXTURE2D(_HeightMap, sampler_HeightMap, currentUV).r;
  	// 分层深度检测
  	[loop]
  	for (int i = 0; i < _MaxLayers; ++i) {
  	if (currentLayerHeight >= currentDepth) break;
  	currentUV -= deltaUV;
  	currentDepth = 1 - SAMPLE_TEXTURE2D(_HeightMap, sampler_HeightMap, currentUV).r;
  	currentLayerHeight += layerHeight;
  	}
  	// 风格化插值修正
  	float2 prevUV = currentUV + deltaUV;
  	float prevDepth = currentDepth - layerHeight;
  	float weight = pow((currentLayerHeight - currentDepth) / (prevDepth - currentDepth + 0.001), 2);
  	return lerp(currentUV, prevUV, saturate(weight * 1.5));
  	}
  	// 风格化光照计算
  	half3 StylizedShading(float3 normalWS, float3 viewDirWS, float NdotL)
  	{
  	float rim = pow(1 - saturate(dot(normalWS, viewDirWS)), _RimPower);
  	float2 rampUV = float2(NdotL * 0.5 + 0.5, 0.5);
  	half3 rampColor = SAMPLE_TEXTURE2D(_RampTex, sampler_RampTex, rampUV).rgb;
  	return lerp(rampColor * _ShadowTint.rgb, rampColor, saturate(NdotL + rim));
  	}
  	ENDHLSL
  	Pass
  	{
  	HLSLPROGRAM
  	#pragma vertex vert
  	#pragma fragment frag
  	struct Attributes
  	{
  	float4 positionOS : POSITION;
  	float2 uv : TEXCOORD0;
  	float3 normalOS : NORMAL;
  	float4 tangentOS : TANGENT;
  	};
  	struct Varyings
  	{
  	float4 positionCS : SV_POSITION;
  	float2 uv : TEXCOORD0;
  	float3 viewDirTS : TEXCOORD1;
  	float3 normalWS : TEXCOORD2;
  	float3 viewDirWS : TEXCOORD3;
  	float4 shadowCoord : TEXCOORD4;
  	};
  	Varyings vert(Attributes IN)
  	{
  	Varyings OUT;
  	VertexPositionInputs posInput = GetVertexPositionInputs(IN.positionOS.xyz);
  	OUT.positionCS = posInput.positionCS;
  	VertexNormalInputs normInput = GetVertexNormalInputs(IN.normalOS, IN.tangentOS);
  	float3 viewDirWS = GetWorldSpaceViewDir(posInput.positionWS);
  	OUT.viewDirTS = TransformWorldToTangent(viewDirWS,
  	normInput.tangentWS, normInput.bitangentWS, normInput.normalWS);
  	OUT.normalWS = normInput.normalWS;
  	OUT.viewDirWS = viewDirWS;
  	OUT.shadowCoord = GetShadowCoord(posInput);
  	OUT.uv = IN.uv;
  	return OUT;
  	}
  	half4 frag(Varyings IN) : SV_Target
  	{
  	// 计算陡峭视差UV
  	float2 parallaxUV = SteepParallaxMapping(normalize(IN.viewDirTS), IN.uv);
  	// 采样纹理
  	half4 albedo = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, parallaxUV);
  	half3 normalTS = UnpackNormal(SAMPLE_TEXTURE2D(_NormalMap, sampler_NormalMap, parallaxUV));
  	// 转换法线到世界空间
  	float3x3 TBN = float3x3(
  	normalize(cross(IN.normalWS, IN.viewDirWS)),
  	normalize(IN.normalWS),
  	normalize(IN.viewDirWS)
  	);
  	float3 normalWS = mul(TBN, normalTS);
  	// 光照计算
  	Light mainLight = GetMainLight(IN.shadowCoord);
  	float NdotL = saturate(dot(normalWS, mainLight.direction));
  	half3 lighting = StylizedShading(normalWS, normalize(IN.viewDirWS), NdotL);
  	return half4(albedo.rgb * lighting * mainLight.color, 1);
  	}
  	ENDHLSL
  	}
  	}
  	}