Shader "Custom/TestShader" {
    Properties {
        _Color ("Color", Color) = (1,1,1,1)
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic ("Metallic", Range(0,1)) = 0.0

        _EmissionTex ("Emission", 2D) = "white" {}
        [HDR] _EmissionColor ("Emission color", Color) = (0.5, 0.5, 0.5, 0.5)

        _FlickerPosX ("Flicker position X", float) = 0
        _FlickerPosY ("Flicker position Y", float) = 0
        _FlickerRad ("Flicker radius", float) = 1
        _FlickerIntensive ("Flicker additive multiplier", float) = 5
    }
    SubShader {
        LOD 200
        Tags { "RenderType" = "Opaque" }

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

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

        sampler2D _EmissionTex;

        struct Input {
            float2 uv_EmissionTex;
        };

        half _Glossiness;
        half _Metallic;
        fixed4 _Color;
        float4 _EmissionColor;

        float _FlickerPosX;
        float _FlickerPosY;
        float _FlickerRad;
        float _FlickerIntensive;

        void surf (Input input, inout SurfaceOutputStandard o)
        {
            o.Albedo = _Color;
            float2 flickerPos = (_FlickerPosX, _FlickerPosY);
            float dist = length (flickerPos - input.uv_EmissionTex);
            float emissionMultiplier = 1 + clamp (_FlickerRad - dist, 0, 1) * _FlickerIntensive;

            float4 emission = tex2D (_EmissionTex, input.uv_EmissionTex) * _EmissionColor * emissionMultiplier;
            o.Emission = emission;

            o.Metallic = _Metallic;
            o.Smoothness = _Glossiness;
        }
        ENDCG
    }
    FallBack "Diffuse"
}