Shader "Sukuna/ProjectileSlash"
{
    Properties
    {
        [Header(Colors)]
        [HDR] _MainColor("Core Color", Color) = (0, 0, 0, 1)
        [HDR] _EdgeColor("Edge Glow", Color) = (10, 0, 0, 1)
        _EdgeWidth("Edge Width", Range(0, 1)) = 0.3
        
        [Header(Movement)]
        _FlowSpeed("Flow Speed", Float) = 2.0
        _NoiseMap("Noise Map", 2D) = "white" {}
    }

    SubShader
    {
        Tags { "RenderType"="Transparent" "Queue"="Transparent" }
        LOD 100

        Pass
        {
            ZWrite Off
            Cull Off
            Blend SrcAlpha One

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

            struct Attributes
            {
                float4 positionOS : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct Varyings
            {
                float4 positionCS : SV_POSITION;
                float2 uv : TEXCOORD0;
            };

            float4 _MainColor;
            float4 _EdgeColor;
            float _EdgeWidth;
            float _FlowSpeed;
            sampler2D _NoiseMap;
            float4 _NoiseMap_ST;

            Varyings vert(Attributes input)
            {
                Varyings output;
                output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
                output.uv = input.uv;
                return output;
            }

            half4 frag(Varyings input) : SV_Target
            {
                float x = input.uv.x;
                float y = input.uv.y;

                // Shape: Nhọn ở đầu (x=1), phình ở giữa
                float shape = (1.0 - abs(y * 2.0 - 1.0)) * pow(x, 2.0);
                
                // Hiệu ứng "cuộn" bên trong lưỡi đao
                float2 noiseUV = input.uv * _NoiseMap_ST.xy + _NoiseMap_ST.zw;
                noiseUV.x -= _Time.y * _FlowSpeed;
                float noise = tex2D(_NoiseMap, noiseUV).r;

                float4 finalColor = lerp(_MainColor, _EdgeColor, smoothstep(1.0 - _EdgeWidth, 1.0, shape * noise));
                finalColor.a = shape;

                return finalColor;
            }
            ENDHLSL
        }
    }
}