Demo 79 - Diffuse and Emission

Shader "Custom/Lighting/Emission"
{
    Properties
    {
        [Header(Diffuse)]
        _Color ("Color", Color) = (1.0, 1.0, 1.0, 1.0)
        _Diffuse ("Diffuse value", Range(0, 1)) = 1.0
        [Header(Emission)]
        _MainTex ("Emissive Map", 2D) = "white" {}
        [HDR] _EmissionColor ("Emission Color", Color) = (0,0,0)
        _Threshold ("Threshold", Range(0., 1.)) = 1.
    }
    SubShader
    {
        Tags { "LightMode"="ForwardBase" }

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct v2f {
                float4 pos : SV_POSITION;
                fixed4 col : COLOR0;
                float2 uv : TEXCOORD0;
            };

            fixed4 _Color;
            fixed4 _LightColor0;
            float _Diffuse;

            sampler2D _MainTex;
            float4 _MainTex_ST;

            v2f vert(appdata_base v) {
                v2f o;
                o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                float3 worldNormal = normalize(mul(v.normal, (float3x3)unity_WorldToObject));
                float3 lightDir = normalize(_WorldSpaceLightPos0.xyz);
                float NdotL = max(0.0, dot(worldNormal, lightDir));
                fixed4 diff = _Color * NdotL * _LightColor0 * _Diffuse;
                o.col = diff;
                o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
                return o;
            }

            float4 _EmissionColor;
            float _Threshold;

            fixed4 frag(v2f i) : SV_Target {
                fixed3 emi = tex2D(_MainTex, i.uv).r * _EmissionColor.rgb * _Threshold;
                i.col.rgb += emi;
                return i.col;
            }

            ENDCG
        }
    }
}