// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
// Upgrade NOTE: replaced '_World2Object' with 'unity_WorldToObject'
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Unity Shaders Book/Chapter 6/Blinn-Phong" {
	Properties {
		// _Diffuse ("Diffuse", Color) = (1, 1, 1, 1)
		_Specular ("Specular", Color) = (1, 1, 1, 1)
		_Gloss ("Gloss", Range(8.0, 256)) = 20
	}
	SubShader {
		Pass { 
			Tags { "LightMode"="ForwardBase" }
		
			CGPROGRAM
			
			#pragma vertex vert
			#pragma fragment frag
			
			#include "Lighting.cginc"
			
			fixed4 _Diffuse;
			fixed4 _Specular;
			float _Gloss;
			
			struct a2v {
				float4 vertex : POSITION;
				float3 normal : NORMAL;
			};
			
			struct v2f {
				float4 pos : SV_POSITION;
				float3 worldNormal : TEXCOORD0;
				float3 worldPos : TEXCOORD1;
			};
			
			v2f vert(a2v v) {
				v2f o;
				// Transform the vertex from object space to projection space
				o.pos = UnityObjectToClipPos(v.vertex);
				
				// Transform the normal from object space to world space
				//o.worldNormal = mul(v.normal, (float3x3)unity_WorldToObject);
				o.worldNormal = UnityObjectToWorldNormal(v.normal);
				// Transform the vertex from object spacet to world space
				o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
				
				return o;
			}
			
			fixed4 frag(v2f i) : SV_Target {
				// Get ambient term
				//fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				
				fixed3 worldNormal = normalize(i.worldNormal);
				fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
				
				// Compute diffuse term
				//fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * max(0, dot(worldNormal, worldLightDir));
				
				// Get the view direction in world space
				fixed3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);
				// Get the half direction in world space
				fixed3 halfDir = normalize(worldLightDir + viewDir);
				// Compute specular term
				fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(worldNormal, halfDir)), _Gloss);
				
				//return fixed4(ambient + diffuse + specular, 1.0);
				return fixed4(specular, 1.0);
			}
			
			ENDCG
		}
	} 
	FallBack "Specular"
}