//
// 1. Add a Quad in Unity
// 2. Parent the quad under camera, to prevent frustum culling.
// 3. Attach this shader.
//
Shader "Quad/Fullscreen"
{
    Properties
    {
    }

    SubShader
    {
        Cull Off ZWrite Off

        Pass
        {
            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 = v.vertex;
                o.vertex.xy *= 2;
                o.uv = v.uv;
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                return fixed4(i.uv, 0, 1);
            }
            ENDCG
        }
    }
}