/*
This shader is used to render the impostor while clearing out the alpha of the eye buffer
The important details here are:
- the use of the Geometry+1 queue to make sure the impostor is drawn after all other opaque objects but before alpha
- the keepalpha parameter that allow unity to actually write the alpha we return at the end of the shader.
*/

Shader "Oculus/Underlay Impostor" {
    Properties{
        _Color("Color", Color) = (1,1,1,1)
        _MainTex("Albedo (RGB)", 2D) = "white" {}
        _Glossiness("Smoothness", Range(0,1)) = 0.5
        _Metallic("Metallic", Range(0,1)) = 0.0
    }
        SubShader{
            Tags { "Queue" = "Geometry+1" "RenderType" = "Opaque" }
            LOD 200

            CGPROGRAM
            // Physically based Standard lighting model, and enable shadows on all light types
            #pragma surface surf Standard fullforwardshadows keepalpha

            // Use shader model 3.0 target, to get nicer looking lighting
            #pragma target 3.0

            sampler2D _MainTex;

            struct Input {
                float2 uv_MainTex;
            };

            half _Glossiness;
            half _Metallic;
            fixed4 _Color;

            void surf(Input IN, inout SurfaceOutputStandard o) {
                // Albedo comes from a texture tinted by color
                fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
                o.Albedo = c.rgb;
                // Metallic and smoothness come from slider variables
                o.Metallic = _Metallic;
                o.Smoothness = _Glossiness;
                o.Alpha = 0.f;
            }
            ENDCG
        }
            FallBack "Diffuse"
}