看到蛮牛有人想要两个带透明通道的图片叠加，就是最简单的纹理混合，想想其实实现起来应该很简单，但是搜了一下还真没搜到，这里简单实现一下，要求底图需要是不透明的：

image.png

image.png

image.png

在系统创建的ImageEffectShader基础上略改一下：

Shader "Hidden/图片叠加"
{Properties{_MainTex ("Texture", 2D) = "white" {}_BlendTex ("Blend Texture", 2D) = "white" {}_Blend("Blend", Range(0,1)) = 0}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = v.uv;return o;}sampler2D _MainTex;sampler2D _BlendTex;float _Blend;fixed4 frag (v2f i) : SV_Target{//获取两个贴图的颜色信息fixed4 col = tex2D(_MainTex, i.uv);fixed4 blendcol = tex2D(_BlendTex, i.uv);//增加_Blend值控制第二张贴图的混合度//saturate限制到0-1float blend=saturate(blendcol.a-_Blend);//如果叠加贴图当前像素透明度为0，则取底图像素，否则取叠加图片的像素fixed4 color=col*(1-blend)+blendcol*blend;return color;}ENDCG}}
}

如果想要底图也带透明通道，可以将底图颜色再乘一下底图的alpha，然后开启图片的透明通道设置即可：

image.png

image.png

Shader "Hidden/图片叠加"
{Properties{_MainTex ("Texture", 2D) = "white" {}_BlendTex ("Blend Texture", 2D) = "white" {}_Blend("Blend", Range(0,1)) = 0}SubShader{Tags{ "Queue" = "Transparent" "RenderType" = "Transparent" }Blend SrcAlpha OneMinusSrcAlpha// No culling or depthCull Off ZWrite Off ZTest AlwaysPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = v.uv;return o;}sampler2D _MainTex;sampler2D _BlendTex;float _Blend;fixed4 frag (v2f i) : SV_Target{//获取两个贴图的颜色信息fixed4 col = tex2D(_MainTex, i.uv);fixed4 blendcol = tex2D(_BlendTex, i.uv);//增加_Blend值控制第二张贴图的混合度//saturate限制到0-1float blend=saturate(blendcol.a-_Blend);//如果叠加贴图当前像素透明度为0，则取底图像素，否则取叠加图片的像素fixed4 color=col*(1-blend)*col.a+blendcol*blend;return color;}ENDCG}}
}