Merged Cake and Abel branched into 2.0.3 (#131)

Co-authored-by: azyges <aaaaaa@aaa.aaa>
Co-authored-by: cake <admin@cakeandbanana.nl>
Co-authored-by: defnotken <itsdefnotken@gmail.com>
Reviewed-on: #131

LightlessSync/ThirdParty/MeshDecimator/Algorithms/DecimationAlgorithm.cs

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+#region License
+/*
+MIT License
+
+Copyright(c) 2017-2018 Mattias Edlund
+
+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.
+*/
+#endregion
+
+using System;
+using Microsoft.Extensions.Logging;
+
+namespace MeshDecimator.Algorithms
+{
+    /// <summary>
+    /// A decimation algorithm.
+    /// </summary>
+    public abstract class DecimationAlgorithm
+    {
+        #region Delegates
+        /// <summary>
+        /// A callback for decimation status reports.
+        /// </summary>
+        /// <param name="iteration">The current iteration, starting at zero.</param>
+        /// <param name="originalTris">The original count of triangles.</param>
+        /// <param name="currentTris">The current count of triangles.</param>
+        /// <param name="targetTris">The target count of triangles.</param>
+        public delegate void StatusReportCallback(int iteration, int originalTris, int currentTris, int targetTris);
+        #endregion
+
+        #region Fields
+        private bool preserveBorders = false;
+        private int maxVertexCount = 0;
+        private bool verbose = false;
+
+        private StatusReportCallback statusReportInvoker = null;
+        #endregion
+
+        #region Properties
+        /// <summary>
+        /// Gets or sets if borders should be kept.
+        /// Default value: false
+        /// </summary>
+        [Obsolete("Use the 'DecimationAlgorithm.PreserveBorders' property instead.", false)]
+        public bool KeepBorders
+        {
+            get { return preserveBorders; }
+            set { preserveBorders = value; }
+        }
+
+        /// <summary>
+        /// Gets or sets if borders should be preserved.
+        /// Default value: false
+        /// </summary>
+        public bool PreserveBorders
+        {
+            get { return preserveBorders; }
+            set { preserveBorders = value; }
+        }
+
+        /// <summary>
+        /// Gets or sets if linked vertices should be kept.
+        /// Default value: false
+        /// </summary>
+        [Obsolete("This feature has been removed, for more details why please read the readme.", true)]
+        public bool KeepLinkedVertices
+        {
+            get { return false; }
+            set { }
+        }
+
+        /// <summary>
+        /// Gets or sets the maximum vertex count. Set to zero for no limitation.
+        /// Default value: 0 (no limitation)
+        /// </summary>
+        public int MaxVertexCount
+        {
+            get { return maxVertexCount; }
+            set { maxVertexCount = Math.MathHelper.Max(value, 0); }
+        }
+
+        /// <summary>
+        /// Gets or sets if verbose information should be printed in the console.
+        /// Default value: false
+        /// </summary>
+        public bool Verbose
+        {
+            get { return verbose; }
+            set { verbose = value; }
+        }
+
+        /// <summary>
+        /// Gets or sets the logger used for diagnostics.
+        /// </summary>
+        public ILogger? Logger { get; set; }
+        #endregion
+
+        #region Events
+        /// <summary>
+        /// An event for status reports for this algorithm.
+        /// </summary>
+        public event StatusReportCallback StatusReport
+        {
+            add { statusReportInvoker += value; }
+            remove { statusReportInvoker -= value; }
+        }
+        #endregion
+
+        #region Protected Methods
+        /// <summary>
+        /// Reports the current status of the decimation.
+        /// </summary>
+        /// <param name="iteration">The current iteration, starting at zero.</param>
+        /// <param name="originalTris">The original count of triangles.</param>
+        /// <param name="currentTris">The current count of triangles.</param>
+        /// <param name="targetTris">The target count of triangles.</param>
+        protected void ReportStatus(int iteration, int originalTris, int currentTris, int targetTris)
+        {
+            var statusReportInvoker = this.statusReportInvoker;
+            if (statusReportInvoker != null)
+            {
+                statusReportInvoker.Invoke(iteration, originalTris, currentTris, targetTris);
+            }
+        }
+        #endregion
+
+        #region Public Methods
+        /// <summary>
+        /// Initializes the algorithm with the original mesh.
+        /// </summary>
+        /// <param name="mesh">The mesh.</param>
+        public abstract void Initialize(Mesh mesh);
+
+        /// <summary>
+        /// Decimates the mesh.
+        /// </summary>
+        /// <param name="targetTrisCount">The target triangle count.</param>
+        public abstract void DecimateMesh(int targetTrisCount);
+
+        /// <summary>
+        /// Decimates the mesh without losing any quality.
+        /// </summary>
+        public abstract void DecimateMeshLossless();
+
+        /// <summary>
+        /// Returns the resulting mesh.
+        /// </summary>
+        /// <returns>The resulting mesh.</returns>
+        public abstract Mesh ToMesh();
+        #endregion
+    }
+}