Shader "Custom/WaterWave"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}            // Main texture property
        _WaveHeight ("Wave Height", Range(0, 0.2)) = 0.05 // Height of the wave effect
        _Speed ("Wave Speed", Range(0, 5.0)) = 2.0        // Speed of the wave movement
        _Frequency ("Wave Frequency", Range(0, 20.0)) = 5.0 // Frequency of the waves
    }
    SubShader
    {
        Tags { "RenderType"="Transparent" "Queue"="Overlay" }
        LOD 200

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

            struct appdata
            {
                float4 vertex : POSITION;  // Vertex position
                float2 uv : TEXCOORD0;     // UV coordinates
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;     // UV coordinates
                float4 vertex : SV_POSITION; // Vertex position for rendering
            };

            sampler2D _MainTex;  // The main texture
            float _WaveHeight;   // Wave height (amplitude)
            float _Speed;        // Speed of the wave
            float _Frequency;    // Frequency of the wave

            // Vertex function to create wave distortion on top vertices
            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex); // Convert vertex position to clip space
                o.uv = v.uv;

                // Create a wave effect at the top of the image (for uv.y > 0.5)
                if (v.uv.y > 0.5)
                {
                    // Calculate wave displacement using the built-in _Time variable
                    float wave = sin(_Frequency * v.uv.x + _Speed * _Time.y) * _WaveHeight;
                    o.vertex.y += wave; // Offset the y position to create the wave effect
                }

                return o;
            }

            // Fragment shader to render the texture
            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, i.uv); // Sample the texture
                return col; // Return the final color
            }
            ENDCG
        }
    }
    FallBack "Transparent"
}