震荡波Shader_HeatDistort

// Per pixel bumped refraction.
// Uses a normal map to distort the image behind, and
// an additional texture to tint the color.

Shader "HeatDistort" {
Properties {
 _BumpAmt  ("Distortion", range (0,128)) = 10
 _MainTex ("Tint Color (RGB)", 2D) = "white" {}
 _BumpMap ("Normalmap", 2D) = "bump" {}
}

CGINCLUDE
#pragma fragmentoption ARB_precision_hint_fastest
#pragma fragmentoption ARB_fog_exp2
#include "UnityCG.cginc"

sampler2D _GrabTexture : register(s0);
float4 _GrabTexture_TexelSize;
sampler2D _BumpMap : register(s1);
sampler2D _MainTex : register(s2);

struct v2f {
 float4 vertex : POSITION;
 float4 uvgrab : TEXCOORD0;
 float2 uvbump : TEXCOORD1;
 float2 uvmain : TEXCOORD2;
};

uniform float _BumpAmt;

half4 frag( v2f i ) : COLOR
{
 // calculate perturbed coordinates
 half2 bump = UnpackNormal(tex2D( _BumpMap, i.uvbump )).rg; // we could optimize this by just reading the x & y without reconstructing the Z
 float2 offset = bump * _BumpAmt * _GrabTexture_TexelSize.xy;
 i.uvgrab.xy = offset * i.uvgrab.z + i.uvgrab.xy;
 
 half4 col = tex2Dproj( _GrabTexture, i.uvgrab.xyw );
 half4 tint = tex2D( _MainTex, i.uvmain );
 return col * tint;
}
ENDCG

Category {

 // We must be transparent, so other objects are drawn before this one.
 Tags { "Queue"="Transparent+100" "RenderType"="Opaque" }

 SubShader {

  // This pass grabs the screen behind the object into a texture.
  // We can access the result in the next pass as _GrabTexture
  GrabPass {       
   Name "BASE"
   Tags { "LightMode" = "Always" }
   }
   
   // Main pass: Take the texture grabbed above and use the bumpmap to perturb it
   // on to the screen
  Pass {
   Name "BASE"
   Tags { "LightMode" = "Always" }
   
CGPROGRAM
#pragma vertex vert
#pragma fragment frag

struct appdata_t {
 float4 vertex : POSITION;
 float2 texcoord: TEXCOORD0;
};

v2f vert (appdata_t v)
{
 v2f o;
 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
 #if UNITY_UV_STARTS_AT_TOP
 float scale = -1.0;
 #else
 float scale = 1.0;
 #endif
 o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) * 0.5;
 o.uvgrab.zw = o.vertex.zw;
 o.uvbump = MultiplyUV( UNITY_MATRIX_TEXTURE1, v.texcoord );
 o.uvmain = MultiplyUV( UNITY_MATRIX_TEXTURE2, v.texcoord );
 return o;
}
ENDCG
  }
 }

 // ------------------------------------------------------------------
 // Fallback for older cards and Unity non-Pro
 
 SubShader {
  Blend DstColor Zero
  Pass {
   Name "BASE"
   SetTexture [_MainTex] { combine texture }
  }
 }
}

}