[TASK] Initial commit with basic product setup

Assets/Mapbox SDK/Mapbox/Unity/MeshGeneration/Modifiers/MeshModifiers/PolygonMeshModifier.cs

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+namespace Mapbox.Unity.MeshGeneration.Modifiers
+{
+	using System.Collections.Generic;
+	using UnityEngine;
+	using Mapbox.Unity.MeshGeneration.Data;
+	using Assets.Mapbox.Unity.MeshGeneration.Modifiers.MeshModifiers;
+	using System;
+
+	/// <summary>
+	/// Polygon modifier creates the polygon (vertex&triangles) using the original vertex list.
+	/// Currently uses Triangle.Net for triangulation, which occasionally adds extra vertices to maintain a good triangulation so output vertex list might not be exactly same as the original vertex list.
+	/// </summary>
+	[CreateAssetMenu(menuName = "Mapbox/Modifiers/Polygon Mesh Modifier")]
+	public class PolygonMeshModifier : MeshGenerationBase
+	{
+		public override ModifierType Type { get { return ModifierType.Preprocess; } }
+
+		public bool IsClockwise(IList<Vector3> vertices)
+		{
+			double sum = 0.0;
+			_counter = vertices.Count;
+			for (int i = 0; i < _counter; i++)
+			{
+				_v1 = vertices[i];
+				_v2 = vertices[(i + 1) % _counter];
+				sum += (_v2.x - _v1.x) * (_v2.z + _v1.z);
+			}
+			return sum > 0.0;
+		}
+
+		private int _counter, _secondCounter;
+		private Vector3 _v1, _v2;
+
+		public override void Run(VectorFeatureUnity feature, MeshData md, UnityTile tile = null)
+		{
+			if(Criteria!=null && Criteria.Count > 0)
+			{
+				foreach(var criterion in Criteria)
+				{
+					if(criterion.ShouldReplaceFeature(feature))
+					{
+						return;
+					}
+				}
+			}
+
+			_secondCounter = feature.Points.Count;
+			var subset = new List<List<Vector3>>(_secondCounter);
+			Data flatData = null;
+			List<int> result = null;
+			var currentIndex = 0;
+			int vertCount = 0, c2 = 0;
+			List<int> triList = null;
+			List<Vector3> sub = null;
+
+			for (int i = 0; i < _secondCounter; i++)
+			{
+				sub = feature.Points[i];
+				//earcut is built to handle one polygon with multiple holes
+				//point data can contain multiple polygons though, so we're handling them separately here
+
+				vertCount = md.Vertices.Count;
+				if (IsClockwise(sub) && vertCount > 0)
+				{
+					flatData = EarcutLibrary.Flatten(subset);
+					result = EarcutLibrary.Earcut(flatData.Vertices, flatData.Holes, flatData.Dim);
+					c2 = result.Count;
+					if (triList == null)
+					{
+						triList = new List<int>(c2);
+					}
+					else
+					{
+						triList.Capacity = triList.Count + c2;
+					}
+					
+					for (int j = 0; j < c2; j++)
+					{
+						triList.Add(result[j] + currentIndex);
+					}
+					currentIndex = vertCount;
+					subset.Clear();
+				}
+
+				subset.Add(sub);
+
+				c2 = sub.Count;
+				md.Vertices.Capacity = md.Vertices.Count + c2;
+				md.Normals.Capacity = md.Normals.Count + c2;
+				md.Edges.Capacity = md.Edges.Count + c2 * 2;
+				for (int j = 0; j < c2; j++)
+				{
+					md.Edges.Add(vertCount + ((j+ 1) % c2));
+					md.Edges.Add(vertCount + j);
+					md.Vertices.Add(sub[j]);
+					md.Tangents.Add(Constants.Math.Vector3Forward);
+					md.Normals.Add(Constants.Math.Vector3Up);
+				}
+
+			}
+
+			flatData = EarcutLibrary.Flatten(subset);
+			result = EarcutLibrary.Earcut(flatData.Vertices, flatData.Holes, flatData.Dim);
+			c2 = result.Count;
+			if (triList == null)
+			{
+				triList = new List<int>(c2);
+			}
+			else
+			{
+				triList.Capacity = triList.Count + c2;
+			}
+			for (int i = 0; i < c2; i++)
+			{
+				triList.Add(result[i] + currentIndex);
+			}
+
+			md.Triangles.Add(triList);
+		}
+	}
+}