像素铺满全屏.

float4x4 matViewProjection;struct VS_INPUT {   float4 Position : POSITION0;   };struct VS_OUTPUT {   float4 Position : POSITION0;   float2 uv:TEXCOORD;};/*1.顶点坐标转换 :　直接使用顶点的符号.2.纹理坐标 : 将顶点符号从[-1,1]转到[0,1].*/VS_OUTPUT vs_main( VS_INPUT Input ){   VS_OUTPUT Output;   float2 pos = sign(Input.Position.xy);      Output.Position = float4(pos,0,1);   //Output.uv = 0.5 * float2(pos.x,-pos.y) + 0.5;   Output.uv = 0.5 * (float2(pos.x,-pos.y) +1);      return( Output );   }

sampler2D _MainTex;float4 ps_main(float2 uv:TEXCOORD) : COLOR0{      float4 c = tex2D(_MainTex,uv);   return c;}