phong光照

Shader "Custom/phong" {
    Properties {
        _MainTex ("Main Tex", 2D) = "white" {}
        _MainTint("Diffuse Tint",Color)=(1,1,1,1)
        _SpecularColor("Specular Color",Color)=(1,1,1,1)
        _SpecPower("Specular Power",Range(0,30))=1
    }
    SubShader {
        Tags { "RenderType"="opaque" }
        LOD 200

        CGPROGRAM
        // Physically based Standard lighting model, and enable shadows on all light types
        #pragma surface surf Phong alpha:fade nolighting

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

        sampler2D _MainTex;
        float4 _MainTint;
        float4 _SpecularColor;
        float _SpecPower;
        struct Input {
            float2 uv_MainTex;
        };

        fixed4 LightingPhong(SurfaceOutput s,fixed3 lightDir,half3 viewDir,fixed atten)
        {
            //求反射光
            float NdotL = dot(s.Normal,lightDir);
            float3 reflectionVector = normalize(2*s.Normal*NdotL-lightDir);

            //视向量与反射光求点积计算高光
            float spec = pow(max(0,dot(reflectionVector,viewDir)),_SpecPower);
            float3 finalSpec = _SpecularColor.rgb*spec;

            //计算最终光照
            fixed4 c;
            c.rgb = (s.Albedo*_LightColor0.rgb*max(0,NdotL)*atten)+(_LightColor0*finalSpec);
            c.a = s.Alpha;
            return c;
        }
        void surf (Input IN, inout SurfaceOutput o) {

            fixed4 c = tex2D(_MainTex,IN.uv_MainTex);
            o.Albedo = c.rgb;
            o.Alpha = c.a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}