planet rendering

Assets/Triangular.cs

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+using System.Collections.Generic;
+using UnityEngine;
+
+/// <summary>
+/// This script can be used to split a 2D polygon into triangles.
+/// The algorithm supports concave polygons, but not polygons with holes, 
+/// or multiple polygons at once.
+/// Taken from <see cref="http://wiki.unity3d.com/index.php?title=Triangulator"/>
+/// </summary>
+public class Triangulator
+{
+    private readonly List<Vector2> _mPoints;
+
+    public Triangulator(IEnumerable<Vector2> points)
+    {
+        _mPoints = new List<Vector2>(points);
+    }
+
+    public int[] Triangulate()
+    {
+        var indices = new List<int>();
+
+        var n = _mPoints.Count;
+        if (n < 3)
+            return indices.ToArray();
+
+        var V = new int[n];
+        if (Area() > 0)
+        {
+            for (var v = 0; v < n; v++)
+                V[v] = v;
+        }
+        else
+        {
+            for (var v = 0; v < n; v++)
+                V[v] = n - 1 - v;
+        }
+
+        var nv = n;
+        var count = 2 * nv;
+        for (int m = 0, v = nv - 1; nv > 2;)
+        {
+            if (count-- <= 0)
+                return indices.ToArray();
+
+            var u = v;
+            if (nv <= u)
+                u = 0;
+            v = u + 1;
+            if (nv <= v)
+                v = 0;
+            var w = v + 1;
+            if (nv <= w)
+                w = 0;
+
+            if (Snip(u, v, w, nv, V))
+            {
+                int a, b, c, s, t;
+                a = V[u];
+                b = V[v];
+                c = V[w];
+                indices.Add(a);
+                indices.Add(b);
+                indices.Add(c);
+                m++;
+                for (s = v, t = v + 1; t < nv; s++, t++)
+                    V[s] = V[t];
+                nv--;
+                count = 2 * nv;
+            }
+        }
+
+        indices.Reverse();
+        return indices.ToArray();
+    }
+
+    private float Area()
+    {
+        var n = _mPoints.Count;
+        var A = 0.0f;
+        for (int p = n - 1, q = 0; q < n; p = q++)
+        {
+            var pval = _mPoints[p];
+            var qval = _mPoints[q];
+            A += pval.x * qval.y - qval.x * pval.y;
+        }
+        return A * 0.5f;
+    }
+
+    private bool Snip(int u, int v, int w, int n, int[] V)
+    {
+        int p;
+        var A = _mPoints[V[u]];
+        var B = _mPoints[V[v]];
+        var C = _mPoints[V[w]];
+        if (Mathf.Epsilon > (B.x - A.x) * (C.y - A.y) - (B.y - A.y) * (C.x - A.x))
+            return false;
+        for (p = 0; p < n; p++)
+        {
+            if (p == u || p == v || p == w)
+                continue;
+            var P = _mPoints[V[p]];
+            if (InsideTriangle(A, B, C, P))
+                return false;
+        }
+        return true;
+    }
+
+    private static bool InsideTriangle(Vector2 A, Vector2 B, Vector2 C, Vector2 P)
+    {
+        float ax, ay, bx, by, cx, cy, apx, apy, bpx, bpy, cpx, cpy;
+        float cCROSSap, bCROSScp, aCROSSbp;
+
+        ax = C.x - B.x; ay = C.y - B.y;
+        bx = A.x - C.x; by = A.y - C.y;
+        cx = B.x - A.x; cy = B.y - A.y;
+        apx = P.x - A.x; apy = P.y - A.y;
+        bpx = P.x - B.x; bpy = P.y - B.y;
+        cpx = P.x - C.x; cpy = P.y - C.y;
+
+        aCROSSbp = ax * bpy - ay * bpx;
+        cCROSSap = cx * apy - cy * apx;
+        bCROSScp = bx * cpy - by * cpx;
+
+        return aCROSSbp >= 0.0f && bCROSScp >= 0.0f && cCROSSap >= 0.0f;
+    }
+}