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一、物体的屏幕UV坐标

float2 ScreenUV = i.pos.xy / _ScreenParams.xy;

二、抓取屏幕图像

GrabPass{" _A "}        //_A为贴图图像名称

      之后需在Pass中声明该贴图才能在Pass中引用此贴图

三、屏幕抓取并制作热效应代码

Shader"unity/HeatDistort 07"
{Properties{_DistortTex("DistortTex",2D)="white"{}_DistortUV_X("DistortUV_X",int)=0_DistortUV_Y("DistortUV_Y",int)=0_Distort("Distort",Range(0,1))=0}SubShader{Tags{"Queue"="Transparent"}GrabPass{"_Texture"}Pass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"sampler2D _Texture;sampler2D _DistortTex;float4 _DistortTex_ST;float _DistortUV_X;float _DistortUV_Y;float _Distort;struct appdate{float4 vertex : POSITION;float2 uv : TEXCOORD;};struct v2f {float4 pos : SV_POSITION;float2 uv : TEXCOORD;};v2f vert(appdate v){v2f o;o.pos=UnityObjectToClipPos(v.vertex);o.uv=TRANSFORM_TEX(v.uv,_DistortTex)+float2(_DistortUV_X,_DistortUV_Y)*_Time.y;return o;}float4 frag(v2f i):SV_Target{float4 distort=tex2D(_DistortTex,i.uv);float2 ScreenUV=i.pos.xy/_ScreenParams.xy;float2 dis=lerp(ScreenUV,distort,_Distort);float4 tex=tex2D(_Texture,dis);return tex;}ENDCG}}}