Пример #1
0
        static bool generatingClockwisePolygon;         // assigned in GenPolygonMesh, used by EarClipPoint

        public static void GenPolygonMesh(Mesh mesh, List <Vector2> path, PolygonTriangulation triangulation)
        {
            // kinda have to do this, the algorithm relies on knowing this
            generatingClockwisePolygon = ShapesMath.PolygonSignedArea(path) > 0;

            mesh.Clear();             // todo maybe not always do this you know?
            int pointCount = path.Count;

            if (pointCount < 2)
            {
                return;
            }

            int triangleCount      = pointCount - 2;
            int triangleIndexCount = triangleCount * 3;

            int[] meshTriangles = new int[triangleIndexCount];

            if (triangulation == PolygonTriangulation.FastConvexOnly)
            {
                int tri = 0;
                for (int i = 0; i < triangleCount; i++)
                {
                    meshTriangles[tri++] = i + 2;
                    meshTriangles[tri++] = i + 1;
                    meshTriangles[tri++] = 0;
                }
            }
            else
            {
                List <EarClipPoint> pointsLeft = new List <EarClipPoint>(pointCount);
                for (int i = 0; i < pointCount; i++)
                {
                    pointsLeft.Add(new EarClipPoint(i, new Vector2(path[i].x, path[i].y)));
                }
                for (int i = 0; i < pointCount; i++)                    // update prev/next connections
                {
                    EarClipPoint p = pointsLeft[i];
                    p.prev = pointsLeft[(i + pointCount - 1) % pointCount];
                    p.next = pointsLeft[(i + 1) % pointCount];
                }

                int tri = 0;
                int countLeft;
                int safeguard = 1000000;
                while ((countLeft = pointsLeft.Count) >= 3 && (safeguard-- > 0))
                {
                    //for( int k = 0; k < pointsLeft.Count * 2; k++ ) {
                    if (countLeft == 3)
                    {
                        // final triangle
                        meshTriangles[tri++] = pointsLeft[2].vertIndex;
                        meshTriangles[tri++] = pointsLeft[1].vertIndex;
                        meshTriangles[tri++] = pointsLeft[0].vertIndex;
                        break;
                    }

                    // iterate until we find a convex vertex
                    bool foundConvex = false;
                    for (int i = 0; i < countLeft; i++)
                    {
                        EarClipPoint p = pointsLeft[i];
                        if (p.ReflexState == ReflexState.Convex)
                        {
                            // it's convex! now make sure there are no reflex points inside
                            bool canClipEar = true;
                            int  idPrev     = (i + countLeft - 1) % countLeft;
                            int  idNext     = (i + 1) % countLeft;
                            for (int j = 0; j < countLeft; j++)
                            {
                                if (j == i)
                                {
                                    continue;                                          // skip self
                                }
                                if (j == idPrev)
                                {
                                    continue;                                               // skip next
                                }
                                if (j == idNext)
                                {
                                    continue;                                               // skip prev
                                }
                                if (pointsLeft[j].ReflexState == ReflexState.Reflex)
                                {
                                    // found a reflex point, make sure it's outside the triangle
                                    if (ShapesMath.PointInsideTriangle(p.next.pt, p.pt, p.prev.pt, pointsLeft[j].pt, 0f, -0.0001f, 0f))
                                    {
                                        canClipEar = false;                                         // it's inside, rip
                                        break;
                                    }
                                }
                            }

                            if (canClipEar)
                            {
                                meshTriangles[tri++] = p.next.vertIndex;
                                meshTriangles[tri++] = p.vertIndex;
                                meshTriangles[tri++] = p.prev.vertIndex;
                                p.next.MarkReflexUnknown();
                                p.prev.MarkReflexUnknown();
                                (p.next.prev, p.prev.next) = (p.prev, p.next);                                     // update prev/next
                                pointsLeft.RemoveAt(i);
                                foundConvex = true;
                                break;                                 // stop search for more convex edges, restart loop
                            }
                        }
                    }

                    // no convex found??
                    if (foundConvex == false)
                    {
                        Debug.LogError("Invalid polygon triangulation - no convex edges found. Your polygon is likely self-intersecting");
                        goto breakBoth;
                    }
                }

breakBoth:

                if (safeguard < 1)
                {
                    Debug.LogError("Polygon triangulation failed, please report a bug (Shapes/Report Bug) with this exact case included");
                }
            }

            // assign to segments mesh
            List <Vector3> verts3D = new List <Vector3>(pointCount);

            for (int i = 0; i < pointCount; i++)
            {
                verts3D.Add(path[i]);
            }
            mesh.SetVertices(verts3D);
            mesh.subMeshCount = 1;
            mesh.SetTriangles(meshTriangles, 0);
        }