Shader "Elfentier/ScreenTransition"
{
    Properties
    {
        _Progress ("Progress", Range(0, 1)) = 0
        _Color ("Color", Color) = (0, 0, 0, 1)
        // 0: Fade / 1: CircleWipe / 2: HorizontalWipe / 3: DiagonalBlinds
        _Mode ("Mode", Float) = 0
    }
    SubShader
    {
        Tags { "Queue"="Overlay" "IgnoreProjector"="True" "RenderType"="Transparent" }
        Blend SrcAlpha OneMinusSrcAlpha
        ZWrite Off
        Cull Off

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

            float _Progress;
            float4 _Color;
            float _Mode;

            struct appdata { float4 vertex : POSITION; float2 uv : TEXCOORD0; };
            struct v2f { float4 pos : SV_POSITION; float2 uv : TEXCOORD0; };

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

            fixed4 frag (v2f i) : SV_Target
            {
                float alpha = 0;
                if (_Mode < 0.5)
                {
                    // Fade
                    alpha = _Progress;
                }
                else if (_Mode < 1.5)
                {
                    // Circle wipe (中心から広がる円)
                    float2 centered = i.uv - 0.5;
                    centered.x *= _ScreenParams.x / _ScreenParams.y;
                    float dist = length(centered);
                    float radius = (1.0 - _Progress) * 0.9;
                    alpha = smoothstep(radius, radius - 0.02, dist);
                }
                else if (_Mode < 2.5)
                {
                    // Horizontal wipe (左から右へ)
                    alpha = step(i.uv.x, _Progress) ;
                }
                else
                {
                    // Diagonal blinds (斜めブラインド)
                    float band = frac((i.uv.x + i.uv.y) * 5.0);
                    alpha = step(band, _Progress);
                }
                return fixed4(_Color.rgb, alpha * _Color.a);
            }
            ENDCG
        }
    }
}