Fishing2/Packages/com.nwh.dynamicwaterphysics/Runtime/Lib/MIConvexHull/Triangulation/VoronoiMesh.cs

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// ║    Copyright © 2025 NWH Coding d.o.o.  All rights reserved.    ║
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/******************************************************************************
 *
 * The MIT License (MIT)
 *
 * MIConvexHull, Copyright (c) 2015 David Sehnal, Matthew Campbell
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 *****************************************************************************/

#region

using System;
using System.Collections.Generic;
using System.Linq;

#endregion

namespace NWH.DWP2.MiConvexHull
{
    /// <summary>
    /// A factory class for creating a Voronoi mesh.
    /// </summary>
    public static class VoronoiMesh
    {
        /// <summary>
        /// Create the voronoi mesh.
        /// </summary>
        /// <typeparam name="TVertex"> The type of the t vertex. </typeparam>
        /// <typeparam name="TCell"> The type of the t cell. </typeparam>
        /// <typeparam name="TEdge"> The type of the t edge. </typeparam>
        /// <param name="data"> The data. </param>
        /// <param name="config"> If null, default TriangulationComputationConfig is used. </param>
        /// <returns> VoronoiMesh&lt;TVertex, TCell, TEdge&gt;. </returns>
        public static VoronoiMesh<TVertex, TCell, TEdge> Create<TVertex, TCell, TEdge>(IList<TVertex> data)
            where TCell : TriangulationCell<TVertex, TCell>, new()
            where TVertex : IVertex
            where TEdge : VoronoiEdge<TVertex, TCell>, new()
        {
            return VoronoiMesh<TVertex, TCell, TEdge>.Create(data);
        }


        /// <summary>
        /// Create the voronoi mesh.
        /// </summary>
        /// <typeparam name="TVertex"> The type of the t vertex. </typeparam>
        /// <param name="data"> The data. </param>
        /// <param name="config"> If null, default TriangulationComputationConfig is used. </param>
        /// <returns>
        /// VoronoiMesh&lt;TVertex, DefaultTriangulationCell&lt;TVertex&gt;, VoronoiEdge&lt;TVertex,
        /// DefaultTriangulationCell&lt;TVertex&gt;&gt;&gt;.
        /// </returns>
        public static
            VoronoiMesh
            <TVertex, DefaultTriangulationCell<TVertex>, VoronoiEdge<TVertex, DefaultTriangulationCell<TVertex>>>
            Create<TVertex>(IList<TVertex> data)
            where TVertex : IVertex
        {
            return
                VoronoiMesh
                <TVertex, DefaultTriangulationCell<TVertex>, VoronoiEdge<TVertex, DefaultTriangulationCell<TVertex>>
                >.Create(data);
        }


        /// <summary>
        /// Create the voronoi mesh.
        /// </summary>
        /// <param name="data"> The data. </param>
        /// <param name="config"> If null, default TriangulationComputationConfig is used. </param>
        /// <returns>
        /// VoronoiMesh&lt;DefaultVertex, DefaultTriangulationCell&lt;DefaultVertex&gt;, VoronoiEdge&lt;DefaultVertex,
        /// DefaultTriangulationCell&lt;DefaultVertex&gt;&gt;&gt;.
        /// </returns>
        public static
            VoronoiMesh
            <DefaultVertex, DefaultTriangulationCell<DefaultVertex>,
                VoronoiEdge<DefaultVertex, DefaultTriangulationCell<DefaultVertex>>>
            Create(IList<double[]> data)
        {
            List<DefaultVertex> points = data.Select(p => new DefaultVertex { Position = p.ToArray(), }).ToList();
            return
                VoronoiMesh
                <DefaultVertex, DefaultTriangulationCell<DefaultVertex>,
                    VoronoiEdge<DefaultVertex, DefaultTriangulationCell<DefaultVertex>>>.Create(points);
        }


        /// <summary>
        /// Create the voronoi mesh.
        /// </summary>
        /// <typeparam name="TVertex"> The type of the t vertex. </typeparam>
        /// <typeparam name="TCell"> The type of the t cell. </typeparam>
        /// <param name="data"> The data. </param>
        /// <param name="config"> If null, default TriangulationComputationConfig is used. </param>
        /// <returns> VoronoiMesh&lt;TVertex, TCell, VoronoiEdge&lt;TVertex, TCell&gt;&gt;. </returns>
        public static VoronoiMesh<TVertex, TCell, VoronoiEdge<TVertex, TCell>> Create<TVertex, TCell>(
            IList<TVertex> data)
            where TVertex : IVertex
            where TCell : TriangulationCell<TVertex, TCell>, new()
        {
            return VoronoiMesh<TVertex, TCell, VoronoiEdge<TVertex, TCell>>.Create(data);
        }
    }

    /// <summary>
    /// A representation of a voronoi mesh.
    /// </summary>
    /// <typeparam name="TEdge"> The type of the t edge. </typeparam>
    /// <typeparam name="TVertex"> The type of the t vertex. </typeparam>
    /// <typeparam name="TCell"> The type of the t cell. </typeparam>
    public class VoronoiMesh<TVertex, TCell, TEdge>
        where TCell : TriangulationCell<TVertex, TCell>, new()
        where TVertex : IVertex
        where TEdge : VoronoiEdge<TVertex, TCell>, new()
    {
        /// <summary>
        /// Can only be created using a factory method.
        /// </summary>
        private VoronoiMesh()
        {
        }


        /// <summary>
        /// Vertices of the diagram.
        /// </summary>
        /// <value> The vertices. </value>
        public IEnumerable<TCell> Vertices { get; private set; }

        /// <summary>
        /// Edges connecting the cells.
        /// The same information can be retrieved Cells' Adjacency.
        /// </summary>
        /// <value> The edges. </value>
        public IEnumerable<TEdge> Edges { get; private set; }


        /// <summary>
        /// Create a Voronoi diagram of the input data.
        /// </summary>
        /// <param name="data"> The data. </param>
        /// <param name="config"> If null, default TriangulationComputationConfig is used. </param>
        /// <returns> VoronoiMesh&lt;TVertex, TCell, TEdge&gt;. </returns>
        /// <exception cref="ArgumentNullException"> data </exception>
        public static VoronoiMesh<TVertex, TCell, TEdge> Create(IList<TVertex> data)
        {
            if (data == null)
            {
                throw new ArgumentNullException("data");
            }

            DelaunayTriangulation<TVertex, TCell> t        = DelaunayTriangulation<TVertex, TCell>.Create(data);
            List<TCell>                           vertices = t.Cells.ToList();
            HashSet<TEdge>                        edges    = new(new EdgeComparer());

            foreach (TCell f in vertices)
            {
                for (int i = 0; i < f.Adjacency.Length; i++)
                {
                    TCell af = f.Adjacency[i];
                    if (af != null)
                    {
                        edges.Add(new TEdge { Source = f, Target = af, });
                    }
                }
            }

            return new VoronoiMesh<TVertex, TCell, TEdge>
            {
                Vertices = vertices,
                Edges    = edges.ToList(),
            };
        }


        /// <summary>
        /// This is probably not needed, but might make things a tiny bit faster.
        /// </summary>
        /// <seealso cref="System.Collections.Generic.IEqualityComparer{TEdge}" />
        private class EdgeComparer : IEqualityComparer<TEdge>
        {
            /// <summary>
            /// Determines whether the specified objects are equal.
            /// </summary>
            /// <param name="x"> The first object of type <paramref name="T" /> to compare. </param>
            /// <param name="y"> The second object of type <paramref name="T" /> to compare. </param>
            /// <returns> true if the specified objects are equal; otherwise, false. </returns>
            public bool Equals(TEdge x, TEdge y)
            {
                return (x.Source == y.Source && x.Target == y.Target) || (x.Source == y.Target && x.Target == y.Source);
            }


            /// <summary>
            /// Returns a hash code for this instance.
            /// </summary>
            /// <param name="obj"> The <see cref="T:System.Object" /> for which a hash code is to be returned. </param>
            /// <returns> A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table. </returns>
            public int GetHashCode(TEdge obj)
            {
                return obj.Source.GetHashCode() ^ obj.Target.GetHashCode();
            }
        }
    }
}