Shader "Builtin Object Id"
{
    SubShader
    {
        Pass
        {
            Name "ObjectId"
            Tags { "LightMode" = "ObjectId" }
            Cull Back
            ZWrite On
            ZTest LEqual
            HLSLPROGRAM
            #pragma target 4.5
            #pragma vertex MainVS
            #pragma fragment MainPS
            cbuffer PerObjectConstants : register(b0)
            {
                float4x4 gProjectionMatrix;
                float4x4 gViewMatrix;
                float4x4 gModelMatrix;
                float4 gObjectIdColor;
            };

            struct VSInput
            {
                float3 position : POSITION;
            };

            struct PSInput
            {
                float4 position : SV_POSITION;
            };

            PSInput MainVS(VSInput input)
            {
                PSInput output;
                const float4 positionWS = mul(gModelMatrix, float4(input.position, 1.0));
                const float4 positionVS = mul(gViewMatrix, positionWS);
                output.position = mul(gProjectionMatrix, positionVS);
                return output;
            }

            float4 MainPS(PSInput input) : SV_TARGET
            {
                return gObjectIdColor;
            }
            ENDHLSL
        }
    }
}