// Simplified Diffuse shader. Differences from regular Diffuse one:
// - no Main Color
// - fully supports only 1 directional light. Other lights can affect it, but it will be per-vertex/SH.

Shader "Zhanyou/Mobile/DiffuseEmit" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		_Emission ("Emission", Range(0, 1)) = 0
	}
	SubShader {
		Tags { "RenderType"="Opaque" }

		// Forward Base
		Pass
		{
			Name "FORWARD"
			Tags { "LightMode" = "ForwardBase" }

			CGPROGRAM
			#define UNITY_PASS_FORWARDBASE
			#include "UnityGiBase.cginc"
			#pragma multi_compile_fwdbase
			#pragma multi_compile_fog
			#pragma vertex vert_Base
			#pragma fragment frag
            #pragma multi_compile __ PLAYER_HALO_ON
			uniform sampler2D _MainTex;
			uniform float4 _MainTex_ST;
			uniform half _Emission;

			fixed4 frag(v2f_Base i) : SV_TARGET
			{
				fixed4 c = tex2D(_MainTex, TRANSFORM_TEX(i.uv, _MainTex));
				// 世界法线
				fixed3 worldNormal = fixed3(i.tSpace0.z, i.tSpace1.z, i.tSpace2.z);
				GET_UNITY_GI_COLOR;
				// 自发光功能
                c.rgb = giColor + c.rgb * _Emission;
#if PLAYER_HALO_ON
                    c.rgb += _DirectionalLightColor * LightColorFromWorld(worldPos);
#endif
				UNITY_APPLY_FOG(i.fogCoord, c);
				UNITY_OPAQUE_ALPHA(c.a);
				return c;
			}
			ENDCG
		}

		// Forward Add
		// 注：实际光照贴图只通过meta通道实现，Forward Add仅用于编辑器无光照贴图时预览
		// 简单处理，Forward Add也使用顶点计算光照和视野方向，真实光照参数
		// 该通道可以省去镜面高光等所需参数，因此按常规算法做
		Pass
		{
			Name "FORWARD_ADD"
			Tags { "LightMode" = "ForwardAdd" }
			ZWrite Off
			Blend One One
			CGPROGRAM
			#define UNITY_PASS_FORWARDADD
			#include "UnityGiBase.cginc"
			#pragma multi_compile_fwdadd
			#pragma multi_compile_fog
			#pragma skip_variants INSTANCING_ON
			#pragma vertex vert_Add
			#pragma fragment frag
			uniform sampler2D _MainTex;
			uniform float4 _MainTex_ST;

			fixed4 frag(v2f_Add i) : SV_TARGET
			{
#ifdef LIGHTMAP_ON
					fixed4 c = fixed4(0.0, 0.0, 0.0, 0.0);
#else
					fixed4 c = tex2D(_MainTex, TRANSFORM_TEX(i.uv, _MainTex));
					half NtoL = max(0.0, i.lightDir.z);
					UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);
					c.rgb = c.rgb * atten * _LightColor0.rgb * NtoL;
#endif
				UNITY_APPLY_FOG(i.fogCoord, c);
				UNITY_OPAQUE_ALPHA(c.a);
				return c;
			}
			ENDCG
		}

		// Meta
		Pass
		{
			Name "Meta"
			Tags { "LightMode" = "Meta" }
			Cull Off

			CGPROGRAM
			#define UNITY_PASS_META
			#include "UnityCG.cginc"
			#include "UnityMetaPass.cginc"
			#pragma vertex vert
			#pragma fragment frag
			#pragma skip_variants FOG_LINEAR FOG_EXP FOG_EXP2
			#pragma skip_variants INSTANCING_ON
			
			uniform sampler2D _MainTex;
			uniform float4 _MainTex_ST;
			uniform half _Emission;

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

			v2f vert(appdata_full v) {
				v2f o;
				UNITY_INITIALIZE_OUTPUT(v2f, o);
				o.pos = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
				return o;
			}

			fixed4 frag(v2f i) : SV_TARGET
			{
				fixed4 c = tex2D(_MainTex, i.uv);
				UnityMetaInput metaIN;
				UNITY_INITIALIZE_OUTPUT(UnityMetaInput, metaIN);
				metaIN.Albedo = c.rgb;
				metaIN.Emission = c.rgb * _Emission;
				return UnityMetaFragment(metaIN);
			}
			ENDCG
		}
	}
	Fallback "Mobile/VertexLit"
}