unity-shader-曲面细分与置换贴图

title: unity-shader-曲面细分与置换贴图

categories: Unity3d-Shader

tags: [unity, shader, tessellation, displacement]

date: 2019-05-22 15:37:34

comments: false

低模通过 置换贴图 增加曲面, 表现出高模效果

相比较 法线贴图 , 置换贴图 是真实改变顶点的位置, 会有遮挡, 而 法线贴图 只是在改变 片段 光照的视觉效果, 并不会修改模型的顶点位置.

前篇

• unity 官网说明 - https://docs.unity3d.com/Manual/SL-SurfaceShaderTessellation.html
• Unity默认管线置换贴图与曲面细分 (有法线解决方案) - https://www.wonderm.cc/2019/03/30/Unity-Tess-Displacement/

在细分后采样置换贴图，对顶点进行偏移

需要注意的是在 surf 和 frag 以外采样贴图只能使用 tex2Dlod

使用限制: the shader is automatically compiled into the Shader Model 4.6 target, 只能在 sm4.6 以后才能使用.

测试

• 使用的资源 Organic 2
• shader

  Shader "test/Tessellation" {
      Properties {
          _MainTex ("Base (RGB)", 2D) = "white" {}
          _DispTex ("Disp Texture", 2D) = "gray" {}
          _NormalMap ("Normalmap", 2D) = "bump" {}
          _RoughnessMap ("RoughnessMap", 2D) = "white" {}
          _AoMap ("AoMap", 2D) = "white" {}
          _Displacement ("Displacement", Range(0, 1.0)) = 0.3
          _Color ("Color", color) = (1,1,1,0)
          _Metallic ("Metallic", Range(0, 1.0)) = 1.0
      }
      SubShader {
          Tags { "RenderType"="Opaque" }
          LOD 300
          
          CGPROGRAM
          #include "UnityPBSLighting.cginc"
          #pragma surface surf Standard addshadow fullforwardshadows vertex:disp nolightmap
          #pragma target 4.6
  
          struct appdata {
              float4 vertex : POSITION;
              float4 tangent : TANGENT;
              float3 normal : NORMAL;
              float2 texcoord : TEXCOORD0;
          };
  
          sampler2D _DispTex;
          float _Displacement;
  
          void disp (inout appdata v) {
              float d = tex2Dlod(_DispTex, float4(v.texcoord.xy,0,0)).r * _Displacement;
              v.vertex.xyz += v.normal * d;
          }
  
          struct Input {
              float2 uv_MainTex;
          };
  
          sampler2D _MainTex;
          sampler2D _NormalMap;
          sampler2D _RoughnessMap;
          sampler2D _AoMap;
          fixed4 _Color;
          float _Metallic;
  
          void surf (Input IN, inout SurfaceOutputStandard o) {
              half4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
              o.Albedo = c.rgb;
              o.Metallic = _Metallic;
              o.Normal = UnpackNormal(tex2D(_NormalMap, IN.uv_MainTex));
              o.Smoothness = 1 - tex2D(_RoughnessMap, IN.uv_MainTex).r;
              o.Occlusion = tex2D(_AoMap, IN.uv_MainTex).r;
          }
          ENDCG
      }
      FallBack "Diffuse"
  }
             

• 效果