Shader "Hidden/Griffin/ElevationPainter"
{
	Properties
	{
		_MainTex("MainTex", 2D) = "black" {}
		_MainTex_Left("MainTex_Left", 2D) = "black" {}
		_MainTex_TopLeft("MainTex_TopLeft", 2D) = "black" {}
		_MainTex_Top("MainTex_Top", 2D) = "black" {}
		_MainTex_TopRight("MainTex_TopRight", 2D) = "black" {}
		_MainTex_Right("MainTex_Right", 2D) = "black" {}
		_MainTex_BottomRight("MainTex_BottomRight", 2D) = "black" {}
		_MainTex_Bottom("MainTex_Bottom", 2D) = "black" {}
		_MainTex_BottomLeft("MainTex_BottomLeft", 2D) = "black" {}

		_Mask("Mask", 2D) = "white" {}
		_Opacity("Opacity", Float) = 1
		_TerrainMask("Terrain Mask", 2D) = "black" {}
	}

		CGINCLUDE
		#include "UnityCG.cginc"
		#include "PaintToolCommon.cginc"

		struct appdata
	{
		float4 vertex : POSITION;
		float2 uv : TEXCOORD0;
	};

	struct v2f
	{
		float2 uv : TEXCOORD0;
		float4 vertex : SV_POSITION;
		float4 localPos : TEXCOORD1;
	};

	sampler2D _MainTex;
	float4 _MainTex_TexelSize;

	sampler2D _MainTex_Left;
	sampler2D _MainTex_TopLeft;
	sampler2D _MainTex_Top;
	sampler2D _MainTex_TopRight;
	sampler2D _MainTex_Right;
	sampler2D _MainTex_BottomRight;
	sampler2D _MainTex_Bottom;
	sampler2D _MainTex_BottomLeft;

	sampler2D _Mask;
	float _Opacity;
	sampler2D _TerrainMask;

	sampler2D textureGrid[3][3];

	v2f vert(appdata v)
	{
		v2f o;
		o.vertex = UnityObjectToClipPos(v.vertex);
		o.uv = v.uv;
		o.localPos = v.vertex;
		return o;
	}

	fixed4 fragRaise(v2f i) : SV_Target
	{
		float terrainMask = 1 - tex2D(_TerrainMask, i.localPos).r;

		float4 maskColor = tex2D(_Mask, i.uv);
		float4 currentColor = tex2D(_MainTex, i.localPos);
		float currentHeight = GriffinDecodeFloatRG(currentColor.rg);
		float desHeight = max(0, min(0.999999, currentHeight + maskColor.r * terrainMask * _Opacity));
		float2 encodedHeight = GriffinEncodeFloatRG(desHeight);

		return saturate(float4(encodedHeight.rg, currentColor.b, currentColor.a));
	}

		fixed4 fragLower(v2f i) : SV_Target
	{
		float terrainMask = 1 - tex2D(_TerrainMask, i.localPos).r;

		float4 maskColor = tex2D(_Mask, i.uv);
		float4 currentColor = tex2D(_MainTex, i.localPos);
		float currentHeight = GriffinDecodeFloatRG(currentColor.rg);
		float desHeight = max(0, min(0.999999, currentHeight - maskColor.r * terrainMask * _Opacity));
		float2 encodedHeight = GriffinEncodeFloatRG(desHeight);

		return saturate(float4(encodedHeight.rg, currentColor.b, currentColor.a));
	}

		fixed4 fragSmooth(v2f i) : SV_Target
	{
		textureGrid[0][0] = _MainTex_BottomLeft;
		textureGrid[1][0] = _MainTex_Bottom;
		textureGrid[2][0] = _MainTex_BottomRight;

		textureGrid[0][1] = _MainTex_Left;
		textureGrid[1][1] = _MainTex;
		textureGrid[2][1] = _MainTex_Right;

		textureGrid[0][2] = _MainTex_TopLeft;
		textureGrid[1][2] = _MainTex_Top;
		textureGrid[2][2] = _MainTex_TopRight;

		float2 texel = _MainTex_TexelSize.xy;
		float avgHeight = 0;
		float sampleCount = 0;

		int indexX = 0;
		int indexY = 0;
		float2 uv = float2(0,0);
		float4 c = float4(0,0,0,0);

		for (int x0 = -3; x0 <= 3; ++x0)
		{
			for (int y0 = -3; y0 <= 3; ++y0)
			{
				uv = i.localPos + float2(x0 * texel.x, y0 * texel.y);

				indexX = lerp(lerp(1, 2, uv.x > 1), 0, uv.x < 0);
				indexY = lerp(lerp(1, 2, uv.y > 1), 0, uv.y < 0);

				uv.x = lerp(lerp(uv.x, uv.x - 1, uv.x > 1), uv.x + 1, uv.x < 0);
				uv.y = lerp(lerp(uv.y, uv.y - 1, uv.y > 1), uv.y + 1, uv.y < 0);

				if (indexX == 0)
				{
					if (indexY == 0)
					{
						c = tex2D(textureGrid[0][0], uv);
					}
					if (indexY == 1)
					{
						c = tex2D(textureGrid[0][1], uv);
					}
					if (indexY == 2)
					{
						c = tex2D(textureGrid[0][2], uv);
					}
				}
				if (indexX == 1)
				{
					if (indexY == 0)
					{
						c = tex2D(textureGrid[1][0], uv);
					}
					if (indexY == 1)
					{
						c = tex2D(textureGrid[1][1], uv);
					}
					if (indexY == 2)
					{
						c = tex2D(textureGrid[1][2], uv);
					}
				}
				if (indexX == 2)
				{
					if (indexY == 0)
					{
						c = tex2D(textureGrid[2][0], uv);
					}
					if (indexY == 1)
					{
						c = tex2D(textureGrid[2][1], uv);
					}
					if (indexY == 2)
					{
						c = tex2D(textureGrid[2][2], uv);
					}
				}
				avgHeight += GriffinDecodeFloatRG(c.rg);

				sampleCount += 1;
			}
		}
		avgHeight = avgHeight / sampleCount;

		float terrainMask = 1 - tex2D(_TerrainMask, i.localPos).r;

		float4 currentColor = tex2D(_MainTex, i.localPos);
		float4 maskColor = tex2D(_Mask, i.uv);

		float maskValue = maskColor.r;
		float currentHeight = GriffinDecodeFloatRG(currentColor.rg);

		float value = max(0, min(0.999999, lerp(currentHeight, avgHeight, maskValue * terrainMask * _Opacity)));
		float2 encodedHeight = GriffinEncodeFloatRG(value);
		return saturate(float4(encodedHeight.rg, currentColor.b, currentColor.a));
	}
		ENDCG

		SubShader
	{
		Tags{ "RenderType" = "Transparent" }

			Pass
		{
			Name "Raise"
			Blend One Zero
			BlendOp Add
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment fragRaise
			ENDCG
		}

			Pass
		{
			Name "Lower"
			Blend One Zero
			BlendOp Add
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment fragLower
			ENDCG
		}

			Pass
		{
			Name "Smooth"
			Blend One Zero
			BlendOp Add
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment fragSmooth
			ENDCG
		}
	}
}