UnderStand Perspective Rasterization, SV_POSITION(gl_FragCoord) to Pixel, SV mean Systems Value

Shader "UnderStandPRR"

{

Properties

{

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

}

SubShader

{

Tags { "RenderType"="Opaque" }

LOD 100

 

Pass

{

CGPROGRAM

#pragma vertex vert

#pragma fragment frag

 

#include "UnityCG.cginc"

 

struct appdata

{

float4 vertex : POSITION;

};

 

struct v2f

{

float4 vertex : SV_POSITION;

};

 

sampler2D _MainTex;

float4 _MainTex_ST;

 

v2f vert (appdata v)

{

v2f o;

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

return o;

}

 

fixed4 frag (v2f i) : SV_Target

{

// i.vertex.xy are pixel coordinates 

// i.vertex.z is depth value 

// i.vertex.w is SV_POSITION w - z value (Perspective interpolation)

return  fixed4(i.vertex.x * (_ScreenParams.z - 1), i.vertex.y * (_ScreenParams.w - 1), i.vertex.z, i.vertex.w);

}

ENDCG

}

}

}