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

// Adapted from the built-in Sprites-Default.shader
// You can download the source for the built-in shaders from:
// http://unity3d.com/unity/download/archive

Shader "UI/SpriteSkewShader"
{
	Properties
	{
		[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
		_Color("Tint", Color) = (1,1,1,1)
		[MaterialToggle] PixelSnap("Pixel snap", Float) = 0

		_HorizontalSkew("Horizontal Skew", Float) = 0
		_VerticalSkew("Vertical Skew", Float) = 0
	}

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

			Cull Off
			Lighting Off
			ZWrite Off
			Fog { Mode Off }
			Blend One OneMinusSrcAlpha

			Pass
			{
			CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma multi_compile DUMMY PIXELSNAP_ON
				#include "UnityCG.cginc"

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

				struct v2f
				{
					float4 vertex   : SV_POSITION;
					fixed4 color : COLOR;
					half2 texcoord  : TEXCOORD0;
				};

				sampler2D _MainTex;
				fixed4 _Color;
				float _HorizontalSkew;
				float _VerticalSkew;

				v2f vert(appdata_t IN)
				{
					v2f OUT;
					OUT.texcoord = IN.texcoord;
					OUT.color = IN.color * _Color;

					// Create a skew transformation matrix
					float h = _HorizontalSkew;
					float v = _VerticalSkew;
					float4x4 transformMatrix = float4x4(
						1,h,0,0,
						v,1,0,0,
						0,0,1,0,
						0,0,0,1);

					float4 skewedVertex = mul(transformMatrix, IN.vertex);
					OUT.vertex = UnityObjectToClipPos(skewedVertex);

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

					return OUT;
				}

				fixed4 frag(v2f IN) : SV_Target
				{
					fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
					c.rgb *= c.a;
					return c;
				}
			ENDCG
			}
		}
}