// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
// Modified with rights for use in demonstration by Lou Garczynski

Shader "Animate UI Material/Example"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)

        _OverlayTex ("Overlay", 2D) = "white" {}
        [HDR]_OverlayColor ("Overlay Color", Color) = (1, 1, 1, 1)
        _Scale ("Scale", Range(0, 2)) = 1
        _Rotation ("Rotation", Range(0, 360)) = 0
        _Offset ("Offset", Vector) = (0, 0, 0, 0)

        _StencilComp ("Stencil Comparison", Float) = 8
        _Stencil ("Stencil ID", Float) = 0
        _StencilOp ("Stencil Operation", Float) = 0
        _StencilWriteMask ("Stencil Write Mask", Float) = 255
        _StencilReadMask ("Stencil Read Mask", Float) = 255

        _ColorMask ("Color Mask", Float) = 15

        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
    }

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

        Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend SrcAlpha OneMinusSrcAlpha
        ColorMask [_ColorMask]

        Pass
        {
            Name "Default"
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 2.0

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile_local _ UNITY_UI_CLIP_RECT
            #pragma multi_compile_local _ UNITY_UI_ALPHACLIP

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

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

            sampler2D _MainTex;
            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;
            float4 _MainTex_ST;
 
            sampler2D _OverlayTex;
            float4 _OverlayColor;
            float _Scale;
            float _Rotation;
            float2 _Offset;

            v2f vert(appdata_t v)
            {
                v2f OUT;
                UNITY_SETUP_INSTANCE_ID(v);
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
                OUT.worldPosition = v.vertex;
                OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);

                OUT.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);

                OUT.color = v.color * _Color;
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;

                // Calculate the overlay texture coordinates and sample it
                float2 centeredUV = (IN.texcoord - 0.5)*2;
                float2 overlayUV = centeredUV * _Scale;
                float rad = _Rotation / 360 * 2 * UNITY_PI;
                float2 rotatedUV = float2(
                    overlayUV.x * cos(rad) - overlayUV.y * sin(rad),
                    overlayUV.x * sin(rad) + overlayUV.y * cos(rad)
                );
                float2 normalizedUV = rotatedUV / 2 + 0.5;
                float2 offsetUV = normalizedUV + float2(_Offset.x, _Offset.y);
                fixed4 overlay = tex2D(_OverlayTex, offsetUV) * _OverlayColor;
 
                // Blend the background and overlay textures
                color = lerp(color, overlay, overlay.a);

                #ifdef UNITY_UI_CLIP_RECT
                color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
                #endif

                #ifdef UNITY_UI_ALPHACLIP
                clip (color.a - 0.001);
                #endif

                return color;
            }
        ENDCG
        }
    }
}