Shader实现物体淡入淡出（转）

3D游戏中经常会用到往前走场景的淡入效果，实际就是物体从透明逐渐变实的过程

用Shader实现非常简单

实现思路：

1 设置淡入的起始距离 和 结束距离

2 在vertex阶段计算物体顶点与相机的距离

3 根据距离计算alpha

Shader如下

Shader"Custom/Fade"{

Properties{

_MainTex("Texture",2D)="white"{}

_FadeDistanceNear("Nearfadeoutdist(ViewSpace)",float)=35

_FadeDistanceFar("Farfadeoutdist(ViewSpace)",float)=40

}

SubShader

{

Tags{"Queue"="Transparent""RenderType"="Transparent"}

ZWriteOn

BlendSrcAlphaOneMinusSrcAlpha

pass

{

CGPROGRAM

#pragmavertexvert

#pragmafragmentfrag

#include"UnityCG.cginc"

sampler2D_MainTex;

float4_MainTex_ST;

structv2f{

float4pos:SV_POSITION;

float2uv:TEXCOORD0;

floatfade:TEXCOORD1;

};

float_FadeDistanceNear;

float_FadeDistanceFar;

v2fvert(appdata_basev)

{

v2fo;

o.pos=mul(UNITY_MATRIX_MVP,v.vertex);

o.uv=TRANSFORM_TEX(v.texcoord,_MainTex);

//相机坐标系的物体坐标

float3posView=mul(UNITY_MATRIX_MV,v.vertex).xyz;

//计算与相机距离

floatdis=length(posView);

//计算fade

o.fade=1-saturate((dis-_FadeDistanceNear)/(_FadeDistanceFar-_FadeDistanceNear));

returno;

}

float4frag(v2fi):COLOR

{

float4texCol=tex2D(_MainTex,i.uv);

float4outp=texCol;

//fade作为alpha

returnfloat4(outp.rgb,i.fade);

}

ENDCG

}

}

}