Shader "Tut/Project/Billboard_1" {

 Properties {

 _MainTex ("Base (RGB)", 2D) = "white" {}

 }

 SubShader {

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

 pass{

 Cull Off

 ZTest Always

 Blend SrcAlpha OneMinusSrcAlpha

 CGPROGRAM

 #pragma vertex vert

 #pragma fragment frag

 #include "UnityCG.cginc"

 sampler2D _MainTex;

 struct v2f {

 float4 pos:SV_POSITION;

 float2 texc:TEXCOORD0;

 };

 v2f vert(appdata_base v)

 {

 v2f o;

 float4 ori=mul(UNITY_MATRIX_MV,float4(,,,));

 float4 vt=v.vertex;

 vt.y=vt.z;//这个平面是沿xz平面 展开的

 vt.z=;//所以只关心其平面上的信息

 //通过加上Object Space的原点在ViewSpace的信息，保持其透视大小

 vt.xyz+=ori.xyz;//result is vt.z==ori.z ,so the distance to camera keeped ,and screen size keeped

 o.pos=mul(UNITY_MATRIX_P,vt);

 o.texc=v.texcoord;

 return o;

 }

 float4 frag(v2f i):COLOR

 {

 return tex2D(_MainTex,i.texc);

 }

 ENDCG

 }//endpass

 }

 }