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

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

Shader "Custom/LitSprite"
{
	Properties
	{
		[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
		_LightStrength ("Light Strength", Float) = 1
		_Color ("Tint", Color) = (1,1,1,1)
		_LightPos ("LightPos", Vector) = (0,0,0,0)
		[MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
		[MaterialToggle] _Pixelated ("Pixelated", Float) = 1


	}

	SubShader
	{
		Tags
		{
			"Queue"="Transparent"
			"IgnoreProjector"="True"
			"RenderType"="Transparent"
			"PreviewType"="Plane"
			"CanUseSpriteAtlas"="True"
		}

		Cull Off
		Lighting Off
		ZWrite Off
		Blend One OneMinusSrcAlpha

		Pass
		{
		CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma target 2.0
			#pragma multi_compile _ PIXELSNAP_ON
			#pragma multi_compile _ ETC1_EXTERNAL_ALPHA

			#include "UnityCG.cginc"

			struct appdata_t
			{
				float4 vertex   : POSITION;
				float4 color    : COLOR;
				float2 texcoord : TEXCOORD0;
				float2 uv       : TEXCOORD1;
			};

			struct v2f
			{
				float4 vertex   : SV_POSITION;
				fixed4 color    : COLOR;
				float2 texcoord : TEXCOORD0;
                float4 worldSpacePosition : float4;
                float2 uv       : TEXCOORD1;
			};

			fixed4 _Color;

			v2f vert(appdata_t IN)
			{
				v2f OUT;

				OUT.vertex = UnityObjectToClipPos(IN.vertex);
				OUT.texcoord = IN.texcoord;
				OUT.color = IN.color * _Color;

				#ifdef PIXELSNAP_ON
					OUT.vertex = UnityPixelSnap (OUT.vertex);
				#endif

				OUT.worldSpacePosition = mul(unity_ObjectToWorld, OUT.vertex);
				OUT.uv = IN.uv;

				return OUT;
			}

			sampler2D _MainTex;
			sampler2D _AlphaTex;
			float _LightStrength;
			Vector _LightPos;
			float _Pixelated;

			fixed4 SampleSpriteTexture (v2f IN)
			{
				float2 uv = IN.texcoord;
				float4 worldPos= IN.worldSpacePosition;

				//x and y are light position.
				float aS = worldPos.x-_LightPos.x;
				float bS = worldPos.y-_LightPos.y;

				if(_Pixelated == 1) {
					float pixelWidth = 1.0f / _LightPos.z;
					float pixelHeight = 1.0f / _LightPos.w;
				}


				fixed4 color = tex2D (_MainTex, uv);

#if ETC1_EXTERNAL_ALPHA
				// get the color from an external texture (usecase: Alpha support for ETC1 on android)
				color.a = tex2D (_AlphaTex, uv).r;
#endif //ETC1_EXTERNAL_ALPHA

				float dist = sqrt((aS * aS) + (bS * bS));

				//light strength.
				float percentClose = 1-(dist/_LightStrength);

				if(color.r + color.g + color.b > 0) {
					color.r = lerp(0, color.r, percentClose);
					color.g = lerp(0, color.g, percentClose);
					color.b = lerp(0, color.b, percentClose);
				}


				return color;
			}

			fixed4 frag(v2f IN) : SV_Target
			{
				fixed4 c = SampleSpriteTexture (IN) * IN.color;
				c.rgb *= c.a;
				return c;
			}
		ENDCG
		}
	}
}