// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

// Simplified VertexLit shader, optimized for high-poly meshes. Differences from regular VertexLit one:
// - less per-vertex work compared with Mobile-VertexLit
// - supports only DIRECTIONAL lights and ambient term, saves some vertex processing power
// - no per-material color
// - no specular
// - no emission

Shader "Codezone/VertexLitSkew (Only Directional Lights)" 
{
	Properties
	{
		_MainTex("Base (RGB)", 2D) = "white" {}
		_Offset("Offset", Vector) = (0,0,0,0)
		_Skew("Skew", Vector) = (0,0,0,0)
	}

	SubShader
	{
		Tags
		{
			"RenderType" = "Opaque" 
		}
		LOD 80

		Pass
		{
			Name "FORWARD"
			Tags
			{
				"LightMode" = "ForwardBase" 
			}

			CGPROGRAM
				#pragma vertex vert_surf
				#pragma fragment frag_surf
				#pragma target 2.0
				#pragma multi_compile_fwdbase
				#pragma multi_compile_fog
				#include "HLSLSupport.cginc"
				#include "UnityCG.cginc"
				#include "Lighting.cginc"
				#include "AutoLight.cginc"

				inline float3 LightingLambertVS(float3 normal, float3 lightDir)
				{
					fixed diff = max(0, dot(normal, lightDir));
					return _LightColor0.rgb * diff;
				}

				sampler2D _MainTex;
				fixed4 _Skew;
				fixed4 _Offset;

				struct Input 
				{
					float2 uv_MainTex;
				};

				void surf(Input IN, inout SurfaceOutput o) 
				{
					half4 c = tex2D(_MainTex, IN.uv_MainTex);
					o.Albedo = c.rgb;
					o.Alpha = c.a;
				}

				struct v2f_surf 
				{
					float4 pos : SV_POSITION;
					float2 pack0 : TEXCOORD0;
					#ifndef LIGHTMAP_ON
					fixed3 normal : TEXCOORD1;
					#endif

					#ifdef LIGHTMAP_ON
					float2 lmap : TEXCOORD2;
					#endif

					#ifndef LIGHTMAP_ON
					fixed3 vlight : TEXCOORD2;
					#endif
					LIGHTING_COORDS(3,4)
					UNITY_FOG_COORDS(5)
					UNITY_VERTEX_OUTPUT_STEREO
				};

				float4 _MainTex_ST;

				v2f_surf vert_surf(appdata_full v)
				{
					v2f_surf o;

					Vector VScreen = mul(UNITY_MATRIX_MV, v.vertex);
					VScreen.x += _Offset.x + (_Skew.x * v.vertex.y);
					VScreen.y += _Offset.y + (_Skew.y * v.vertex.y);
					VScreen.z += _Offset.z + (_Skew.z * v.vertex.y);
					v.vertex = mul(VScreen, UNITY_MATRIX_IT_MV);

					UNITY_SETUP_INSTANCE_ID(v);
					UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
					o.pos = UnityObjectToClipPos(v.vertex);
					o.pack0.xy = TRANSFORM_TEX(v.texcoord, _MainTex);

					#ifdef LIGHTMAP_ON
					o.lmap.xy = v.texcoord1.xy * unity_LightmapST.xy + unity_LightmapST.zw;
					#endif

					float3 worldN = UnityObjectToWorldNormal(v.normal);

					#ifndef LIGHTMAP_ON
					o.normal = worldN;
					o.vlight = ShadeSH9(float4(worldN,1.0));
					o.vlight += LightingLambertVS(worldN, _WorldSpaceLightPos0.xyz);
					#endif

					TRANSFER_VERTEX_TO_FRAGMENT(o);
					UNITY_TRANSFER_FOG(o,o.pos);
					return o;
				}

				fixed4 frag_surf(v2f_surf IN) : SV_Target
				{
					Input surfIN;
					surfIN.uv_MainTex = IN.pack0.xy;
					SurfaceOutput o;
					o.Albedo = 0.0;
					o.Emission = 0.0;
					o.Specular = 0.0;
					o.Alpha = 0.0;
					o.Gloss = 0.0;

					#ifndef LIGHTMAP_ON
					o.Normal = IN.normal;
					#else
					o.Normal = 0;
					#endif

					surf(surfIN, o);
					fixed atten = LIGHT_ATTENUATION(IN);
					fixed4 c = 0;

					#ifndef LIGHTMAP_ON
					c.rgb = o.Albedo * IN.vlight * atten;
					#endif

					#ifdef LIGHTMAP_ON
					fixed3 lm = DecodeLightmap(UNITY_SAMPLE_TEX2D(unity_Lightmap, IN.lmap.xy));
					#ifdef SHADOWS_SCREEN
					c.rgb += o.Albedo * min(lm, atten * 2);
					#else
					c.rgb += o.Albedo * lm;
					#endif
					c.a = o.Alpha;
					#endif

					UNITY_APPLY_FOG(IN.fogCoord, c);
					UNITY_OPAQUE_ALPHA(c.a);
					return c;
				}
			ENDCG
		}
	}

	FallBack "Mobile/VertexLit"
}