unity实现玻璃效果

一、使用Cubemap，做一个假反射

shader代码如下:

Shader "Custom/glassShader" {
  Properties {
    _MainColor("Main Color",Color)=(1,1,1,1)
    _MainTex ("Base (RGB)", 2D) = "white" {}
    _Cube("Cube",CUBE)=""{}
  }
  SubShader {
    Tags {"RenderType"="Opaque"}
    LOD 200

    //cull off

    CGPROGRAM
    #pragma surface surf Lambert alpha

    fixed4 _MainColor;
    sampler2D _MainTex;
    samplerCUBE _Cube;

    struct Input {
      float2 uv_MainTex;
      float3 worldRefl;
    };

    void surf (Input IN, inout SurfaceOutput o) {
      half4 c = tex2D (_MainTex, IN.uv_MainTex);
      o.Albedo = c.rgb*_MainColor.rgb;
      o.Emission=texCUBE(_Cube,IN.worldRefl).rgb;
      o.Alpha = c.a*_MainColor.a;
    }
    ENDCG
  } 

  FallBack "Diffuse"
}      

二、使用GrabPass，抓取屏幕纹理,实现实时反射

Shader "Unlit/GrabGlass"
{
  Properties
  {
    _Color("Main Color",Color)=(1,1,1,1)
    _MainTex ("Texture", 2D) = "white" {}
  }
  SubShader
  {


    Tags {"Queue"="Transparent" "RenderType"="Opaque" }//Opaque
    LOD 100

    //绘制半透明物体 关闭深度缓存
    ZWrite Off
    //透明混合
    Blend SrcAlpha OneMinusSrcAlpha

    //如果没有命名,则可以用_GrabTexture来读取,不过开销很大,应用到特殊效果时才去应用
    GrabPass
    {
        "_GrabTex"
    }

    Pass
    {
      CGPROGRAM
      #pragma vertex vert
      #pragma fragment frag
      // make fog work
      #pragma multi_compile_fog

      #include "UnityCG.cginc"

      struct appdata
      {
        float4 vertex : POSITION;
        float2 uv : TEXCOORD0;
      };

      struct v2f
      {
        float2 uv : TEXCOORD0;
        UNITY_FOG_COORDS(1)
        float4 vertex : SV_POSITION;
      };

      sampler2D _MainTex;
      float4 _MainTex_ST;
      fixed4 _Color;
      sampler2D _GrabTex;

      v2f vert (appdata v)
      {
        v2f o;
        o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
        o.uv = TRANSFORM_TEX(v.uv, _MainTex);
        UNITY_TRANSFER_FOG(o,o.vertex);
        return o;
      }

      fixed4 frag (v2f i) : SV_Target
      {
        // sample the texture
        fixed4 col = tex2D(_MainTex, i.uv)*_Color;

        // apply fog
        UNITY_APPLY_FOG(i.fogCoord, col); 
        //调整一下uv
        float2 uv=i.uv; 
        uv.x=1-uv.x;
        return col*tex2D(_GrabTex,uv);
      }
      ENDCG
    }
  }
}      

效果如下:

三、使用摄像机实现实时反射

因为GrabPass,相对来说消耗较大,只建议用于一些特殊效果，于是这里就借助辅助摄像机，来实现实时反射效果，当然这需要多写一个脚本，同时需要在辅助摄像机中屏蔽玻璃本身

Shader "Unlit/CameraGlass"
{
  Properties
  {
    _MainTex ("Texture", 2D) = "white" {}
  }
  SubShader
  {
    Tags { "RenderType"="Opaque" }
    LOD 100

    Pass
    {
      CGPROGRAM
      #pragma vertex vert
      #pragma fragment frag
      // make fog work
      #pragma multi_compile_fog

      #include "UnityCG.cginc"

      struct appdata
      {
        float4 vertex : POSITION;
        float2 uv : TEXCOORD0;
      };

      struct v2f
      {
        float2 uv : TEXCOORD0;
        UNITY_FOG_COORDS(1)
        float4 vertex : SV_POSITION;
      };

      sampler2D _MainTex;
      float4 _MainTex_ST;

      v2f vert (appdata v)
      {
        v2f o;
        o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
        o.uv = TRANSFORM_TEX(v.uv, _MainTex);
        UNITY_TRANSFER_FOG(o,o.vertex);
        return o;
      }

      fixed4 frag (v2f i) : SV_Target
      {
        // sample the texture  需要调整一下uv
        fixed4 col = tex2D(_MainTex, 1-i.uv);
        // apply fog
        UNITY_APPLY_FOG(i.fogCoord, col);       
        return col;
      }
      ENDCG
    }
  }
}      

脚本代码如下:

using UnityEngine;
using System.Collections;

public class RenderGlassTexture : MonoBehaviour {

    /// <summary>
    /// 辅助摄像机 
    /// 原理:就是将辅助摄像机所看到的内容渲染到玻璃物体上,所以就实现了实时反射的镜面效果
    /// 因为玻璃也是场景中的物体,所以辅助摄像机也会看见他
    /// 所以最好能将玻璃物体单独放在一个层级中,让辅助摄像机不去渲染他
    /// </summary>
    public Camera cam;
    private RenderTexture renderTex;
    /// <summary>
    /// 玻璃shader
    /// </summary>
    public Shader glassShader;
    /// <summary>
    /// 玻璃材质
    /// </summary>
    private Material m_GlassMaterial;
    protected Material GlassMaterial
    {
        get
        {
            if (m_GlassMaterial == null)
            {
                m_GlassMaterial = new Material(glassShader);
            }
            return m_GlassMaterial;
        }
    }

    // Use this for initialization
    void Start () {
        renderTex = new RenderTexture(Screen.width, Screen.height, 16);
        cam.targetTexture = renderTex;
    }

    //在摄像机开始裁剪场景之前调用
    void OnPreCull()
    {
        GlassMaterial.SetTexture("_MainTex", renderTex);
    }

    //在相机完成场景渲染后调用
    void OnPostRender()
    {
        GlassMaterial.SetTexture("_MainTex", null);
    }
}