// Author：Blastom
// Meta Pass和Shadow Caster使用 Fallback
// 这个Shader只用于Non-Directional烘培的物体，动态物体使用光照会不正常；
// 支持GLES 2.0，包括Shader Level 2.0的机器；
// 升级Unity版本如果有算法改变，需要特殊处理。
Shader "Zhanyou/Mobile/DiffuseBumpedEmit" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		[NoScaleOffset]_BumpMap ("Normal Map", 2D) = "bump" {}
		_BumpLerp ("Normal Strength", Range(0, 5)) = 1
		_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 multi_compile __ PLAYER_HALO_ON
			#pragma vertex vert_Base
			#pragma fragment frag

			uniform sampler2D _MainTex;
			uniform float4 _MainTex_ST;
			uniform half _Emission;
#if !T4M_NORMAL_OFF
				uniform sampler2D _BumpMap;
				uniform half _BumpLerp;
#endif

			fixed4 frag(v2f_Base i) : SV_TARGET
			{
				float2 uv =  TRANSFORM_TEX(i.uv, _MainTex);
				fixed4 c = tex2D(_MainTex, uv);
#if T4M_NORMAL_OFF
					fixed3 worldNormal = fixed3(i.tSpace0.z, i.tSpace1.z, i.tSpace2.z);
#else
				    half3 normal = UnpackNormal(tex2D(_BumpMap, uv));
				    // 世界法线
				    fixed3 worldNormal;
				    worldNormal.x = dot(i.tSpace0.xyz, normal);
				    worldNormal.y = dot(i.tSpace1.xyz, normal);
				    worldNormal.z = dot(i.tSpace2.xyz, normal);
					worldNormal = normalize(worldNormal);
#endif
				// 标准UnityGi流程
				GET_UNITY_GI_COLOR;
#if !T4M_NORMAL_OFF
				    // 法线强度调整功能
				    fixed ndotlVert = LambertTerm(fixed3(i.tSpace0.z, i.tSpace1.z, i.tSpace2.z), lightDir);
				    giColor += (ndotl - ndotlVert) * _BumpLerp * SIM_LIGHT_COLOR;
#endif
                // 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;
			uniform sampler2D _BumpMap;

			fixed4 frag(v2f_Add i) : SV_TARGET
			{
#ifdef LIGHTMAP_ON
					fixed4 c = fixed4(0.0, 0.0, 0.0, 0.0);
#else
					float2 uv =  TRANSFORM_TEX(i.uv, _MainTex);
					fixed4 c = tex2D(_MainTex, uv);
					half3 normal = UnpackNormal(tex2D(_BumpMap, uv));
					half NtoL = max(0.0, dot(normal, i.lightDir));
					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
		}
	}
	FallBack "Zhanyou/Mobile/DiffuseEmit"
}