Shader "MyShader/PBRTer3"
{
	Properties {
		_Splat0 ("Layer 1", 2D) = "white" {}
		_Splat1 ("Layer 2", 2D) = "white" {}
		_Splat2 ("Layer 3", 2D) = "white" {}
		_BumpSplat0 ("Layer1Normalmap", 2D) = "bump" {}
		_BumpSplat1 ("Layer2Normalmap", 2D) = "bump" {}
		_BumpSplat2 ("Layer3Normalmap", 2D) = "bump" {}
		_Control ("Control (RGBA)", 2D) = "white" {}

		_Color("MainColor", Color) = (0.5,0.5,0.5,1)
		_NormalScale("Normal Scale", Range(0, 3)) = 1.2
		_LightAdjustMin("light_adjust_min", Range(0, 2)) = 0
		_LightAdjustMax("light_adjust_max", Range(0, 2)) = 1
	}

	CGINCLUDE
		
		#include "UnityCG.cginc"

		sampler2D _Splat0, _Splat1, _Splat2, _BumpSplat0, _BumpSplat1, _BumpSplat2;
		sampler2D _Control;

		half4 _Splat0_ST, _Splat1_ST, _Splat2_ST;
		half _NormalScale, _LightAdjustMin, _LightAdjustMax;
		half4 _Color;

		half4 _GlobalLightColor;
		half4 _GlobalLightDir;

		inline float GGX2(float nh, float hl, float r)
		{
			hl = max (hl, 0.01f);
			float a = max(0.01f, r * r * 0.49f);
			float aa = a * a;
			float M = ((nh * aa) - nh) * nh + 1.0;
			float t = M * hl;
			t *= t;
			t *= (r + 0.5f);
			return  clamp(aa / (4.0f * t), 0, 100);
		}

	ENDCG

	SubShader 
	{
		Tags { "RenderType"="Opaque" }

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma multi_compile_fwdbase
			#pragma multi_compile_fog
			#pragma target 3.0
			#pragma fragmentoption ARB_precision_hint_fastest

			struct a2v 
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float4 tangent	: TANGENT;
				float2 texcoord : TEXCOORD0;
				float2 texcoord1 : TEXCOORD1;
			};

			struct v2f
			{ 
				float4 pos : SV_POSITION;
				float4 uv : TEXCOORD0;
				float4 posWorld : TEXCOORD1;
                float3 normalDir : TEXCOORD2;
                float3 tangentDir : TEXCOORD3;
                float3 bitangentDir : TEXCOORD4;
                float4 splatUv0 : TEXCOORD5;
                float4 splatUv1 : TEXCOORD6;
				UNITY_FOG_COORDS(7)
			};

			v2f vert(a2v v)
			{
				v2f o;
				o.posWorld = mul(unity_ObjectToWorld, v.vertex);
				o.pos = mul(UNITY_MATRIX_VP, o.posWorld);
				o.uv.xy = v.texcoord;
				o.uv.zw = v.texcoord1.xy * unity_LightmapST.xy + unity_LightmapST.zw;

				o.normalDir = mul((float3x3)unity_ObjectToWorld, v.normal);
				o.tangentDir = normalize(mul((float3x3)unity_ObjectToWorld, v.tangent.xyz));
                o.bitangentDir = normalize(cross(o.normalDir, o.tangentDir) * v.tangent.w);

				o.splatUv0.xy = TRANSFORM_TEX(v.texcoord, _Splat0);
				o.splatUv0.zw = TRANSFORM_TEX(v.texcoord, _Splat1);
				o.splatUv1.xy = TRANSFORM_TEX(v.texcoord, _Splat2);
				
				UNITY_TRANSFER_FOG(o, o.pos);
				return o;
			}

			half4 frag (v2f i) : SV_Target
			{
				half4 splat = tex2D (_Control, i.uv.xy);
				half4 cBase = tex2D(_Splat0, i.splatUv0.xy) * splat.r;
				half4 texBump = tex2D(_BumpSplat0, i.splatUv0.xy) * splat.r;

				cBase += tex2D(_Splat1, i.splatUv0.zw) * splat.g;
				texBump += tex2D(_BumpSplat1, i.splatUv0.zw) * splat.g;

				cBase += tex2D(_Splat2, i.splatUv1.xy) * splat.b;
				texBump += tex2D(_BumpSplat2, i.splatUv1.xy) * splat.b;

				cBase.rgb *= cBase.rgb;
				half roughness = cBase.a;
				half metallic = texBump.a;

				float3x3 tangentTransform = float3x3( i.tangentDir, i.bitangentDir, i.normalDir);
				half3 normal = texBump.xyz * 2.0 - 1.0f;
				normal.xy *= _NormalScale;
				normal = normalize(mul(normal, tangentTransform));

				half3 litDir = _GlobalLightDir.xyz;
				half3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.posWorld.xyz);
				half3 halfDir = normalize(litDir + viewDir);

				half ndotl = dot(normal, litDir);
				half nl = max(0, ndotl);
				half nh = clamp(dot(normal, halfDir), 0, 1);
				half lh = clamp(dot(litDir, halfDir), 0, 1);

				half3 cLit = _GlobalLightColor.rgb * nl;
				half3 cDiffuse = (1.0f - metallic) * cBase.rgb;

				float specularTerm = GGX2(nh, lh, roughness);
				half3 finalColor = 0;

				half3 diffTerm = 0;
				half3 lmCol = DecodeLightmap (UNITY_SAMPLE_TEX2D(unity_Lightmap, i.uv.zw)) ;
				finalColor += lmCol * cBase.rgb;
				cLit *= smoothstep (_LightAdjustMin, _LightAdjustMax, Luminance(lmCol.rgb));

				diffTerm += cLit;

				finalColor += (specularTerm * metallic * cLit + cDiffuse * diffTerm);
				finalColor = sqrt(finalColor);
				finalColor *= _Color * 2.0f;
				
				UNITY_APPLY_FOG(i.fogCoord, finalColor);
				return half4(finalColor, 1);
			}
			ENDCG
		}

	}
}