278 lines
10 KiB
Plaintext
278 lines
10 KiB
Plaintext
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/******************************************************************************
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* Spine Runtimes License Agreement
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* Last updated January 1, 2020. Replaces all prior versions.
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*
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* Copyright (c) 2013-2020, Esoteric Software LLC
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*
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* Integration of the Spine Runtimes into software or otherwise creating
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* derivative works of the Spine Runtimes is permitted under the terms and
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* conditions of Section 2 of the Spine Editor License Agreement:
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* http://esotericsoftware.com/spine-editor-license
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*
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* Otherwise, it is permitted to integrate the Spine Runtimes into software
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* or otherwise create derivative works of the Spine Runtimes (collectively,
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* "Products"), provided that each user of the Products must obtain their own
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* Spine Editor license and redistribution of the Products in any form must
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* include this license and copyright notice.
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*
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* THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
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* BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*****************************************************************************/
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using System;
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namespace Spine {
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public class Triangulator {
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private readonly ExposedList<ExposedList<float>> convexPolygons = new ExposedList<ExposedList<float>>();
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private readonly ExposedList<ExposedList<int>> convexPolygonsIndices = new ExposedList<ExposedList<int>>();
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private readonly ExposedList<int> indicesArray = new ExposedList<int>();
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private readonly ExposedList<bool> isConcaveArray = new ExposedList<bool>();
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private readonly ExposedList<int> triangles = new ExposedList<int>();
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private readonly Pool<ExposedList<float>> polygonPool = new Pool<ExposedList<float>>();
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private readonly Pool<ExposedList<int>> polygonIndicesPool = new Pool<ExposedList<int>>();
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public ExposedList<int> Triangulate (ExposedList<float> verticesArray) {
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var vertices = verticesArray.Items;
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int vertexCount = verticesArray.Count >> 1;
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var indicesArray = this.indicesArray;
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indicesArray.Clear();
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int[] indices = indicesArray.Resize(vertexCount).Items;
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for (int i = 0; i < vertexCount; i++)
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indices[i] = i;
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var isConcaveArray = this.isConcaveArray;
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bool[] isConcave = isConcaveArray.Resize(vertexCount).Items;
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for (int i = 0, n = vertexCount; i < n; ++i)
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isConcave[i] = IsConcave(i, vertexCount, vertices, indices);
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var triangles = this.triangles;
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triangles.Clear();
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triangles.EnsureCapacity(Math.Max(0, vertexCount - 2) << 2);
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while (vertexCount > 3) {
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// Find ear tip.
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int previous = vertexCount - 1, i = 0, next = 1;
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// outer:
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while (true) {
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if (!isConcave[i]) {
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int p1 = indices[previous] << 1, p2 = indices[i] << 1, p3 = indices[next] << 1;
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float p1x = vertices[p1], p1y = vertices[p1 + 1];
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float p2x = vertices[p2], p2y = vertices[p2 + 1];
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float p3x = vertices[p3], p3y = vertices[p3 + 1];
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for (int ii = (next + 1) % vertexCount; ii != previous; ii = (ii + 1) % vertexCount) {
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if (!isConcave[ii]) continue;
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int v = indices[ii] << 1;
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float vx = vertices[v], vy = vertices[v + 1];
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if (PositiveArea(p3x, p3y, p1x, p1y, vx, vy)) {
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if (PositiveArea(p1x, p1y, p2x, p2y, vx, vy)) {
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if (PositiveArea(p2x, p2y, p3x, p3y, vx, vy)) goto break_outer; // break outer;
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}
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}
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}
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break;
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}
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break_outer:
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if (next == 0) {
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do {
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if (!isConcave[i]) break;
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i--;
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} while (i > 0);
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break;
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}
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previous = i;
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i = next;
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next = (next + 1) % vertexCount;
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}
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// Cut ear tip.
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triangles.Add(indices[(vertexCount + i - 1) % vertexCount]);
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triangles.Add(indices[i]);
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triangles.Add(indices[(i + 1) % vertexCount]);
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indicesArray.RemoveAt(i);
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isConcaveArray.RemoveAt(i);
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vertexCount--;
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int previousIndex = (vertexCount + i - 1) % vertexCount;
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int nextIndex = i == vertexCount ? 0 : i;
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isConcave[previousIndex] = IsConcave(previousIndex, vertexCount, vertices, indices);
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isConcave[nextIndex] = IsConcave(nextIndex, vertexCount, vertices, indices);
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}
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if (vertexCount == 3) {
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triangles.Add(indices[2]);
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triangles.Add(indices[0]);
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triangles.Add(indices[1]);
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}
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return triangles;
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}
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public ExposedList<ExposedList<float>> Decompose (ExposedList<float> verticesArray, ExposedList<int> triangles) {
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var vertices = verticesArray.Items;
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var convexPolygons = this.convexPolygons;
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for (int i = 0, n = convexPolygons.Count; i < n; i++) {
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polygonPool.Free(convexPolygons.Items[i]);
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}
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convexPolygons.Clear();
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var convexPolygonsIndices = this.convexPolygonsIndices;
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for (int i = 0, n = convexPolygonsIndices.Count; i < n; i++) {
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polygonIndicesPool.Free(convexPolygonsIndices.Items[i]);
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}
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convexPolygonsIndices.Clear();
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var polygonIndices = polygonIndicesPool.Obtain();
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polygonIndices.Clear();
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var polygon = polygonPool.Obtain();
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polygon.Clear();
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// Merge subsequent triangles if they form a triangle fan.
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int fanBaseIndex = -1, lastWinding = 0;
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int[] trianglesItems = triangles.Items;
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for (int i = 0, n = triangles.Count; i < n; i += 3) {
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int t1 = trianglesItems[i] << 1, t2 = trianglesItems[i + 1] << 1, t3 = trianglesItems[i + 2] << 1;
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float x1 = vertices[t1], y1 = vertices[t1 + 1];
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float x2 = vertices[t2], y2 = vertices[t2 + 1];
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float x3 = vertices[t3], y3 = vertices[t3 + 1];
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// If the base of the last triangle is the same as this triangle, check if they form a convex polygon (triangle fan).
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var merged = false;
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if (fanBaseIndex == t1) {
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int o = polygon.Count - 4;
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float[] p = polygon.Items;
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int winding1 = Winding(p[o], p[o + 1], p[o + 2], p[o + 3], x3, y3);
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int winding2 = Winding(x3, y3, p[0], p[1], p[2], p[3]);
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if (winding1 == lastWinding && winding2 == lastWinding) {
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polygon.Add(x3);
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polygon.Add(y3);
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polygonIndices.Add(t3);
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merged = true;
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}
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}
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// Otherwise make this triangle the new base.
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if (!merged) {
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if (polygon.Count > 0) {
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convexPolygons.Add(polygon);
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convexPolygonsIndices.Add(polygonIndices);
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} else {
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polygonPool.Free(polygon);
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polygonIndicesPool.Free(polygonIndices);
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}
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polygon = polygonPool.Obtain();
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polygon.Clear();
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polygon.Add(x1);
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polygon.Add(y1);
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polygon.Add(x2);
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polygon.Add(y2);
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polygon.Add(x3);
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polygon.Add(y3);
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polygonIndices = polygonIndicesPool.Obtain();
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polygonIndices.Clear();
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polygonIndices.Add(t1);
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polygonIndices.Add(t2);
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polygonIndices.Add(t3);
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lastWinding = Winding(x1, y1, x2, y2, x3, y3);
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fanBaseIndex = t1;
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}
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}
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if (polygon.Count > 0) {
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convexPolygons.Add(polygon);
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convexPolygonsIndices.Add(polygonIndices);
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}
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// Go through the list of polygons and try to merge the remaining triangles with the found triangle fans.
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for (int i = 0, n = convexPolygons.Count; i < n; i++) {
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polygonIndices = convexPolygonsIndices.Items[i];
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if (polygonIndices.Count == 0) continue;
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int firstIndex = polygonIndices.Items[0];
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int lastIndex = polygonIndices.Items[polygonIndices.Count - 1];
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polygon = convexPolygons.Items[i];
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int o = polygon.Count - 4;
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float[] p = polygon.Items;
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float prevPrevX = p[o], prevPrevY = p[o + 1];
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float prevX = p[o + 2], prevY = p[o + 3];
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float firstX = p[0], firstY = p[1];
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float secondX = p[2], secondY = p[3];
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int winding = Winding(prevPrevX, prevPrevY, prevX, prevY, firstX, firstY);
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for (int ii = 0; ii < n; ii++) {
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if (ii == i) continue;
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var otherIndices = convexPolygonsIndices.Items[ii];
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if (otherIndices.Count != 3) continue;
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int otherFirstIndex = otherIndices.Items[0];
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int otherSecondIndex = otherIndices.Items[1];
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int otherLastIndex = otherIndices.Items[2];
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var otherPoly = convexPolygons.Items[ii];
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float x3 = otherPoly.Items[otherPoly.Count - 2], y3 = otherPoly.Items[otherPoly.Count - 1];
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if (otherFirstIndex != firstIndex || otherSecondIndex != lastIndex) continue;
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int winding1 = Winding(prevPrevX, prevPrevY, prevX, prevY, x3, y3);
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int winding2 = Winding(x3, y3, firstX, firstY, secondX, secondY);
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if (winding1 == winding && winding2 == winding) {
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otherPoly.Clear();
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otherIndices.Clear();
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polygon.Add(x3);
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polygon.Add(y3);
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polygonIndices.Add(otherLastIndex);
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prevPrevX = prevX;
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prevPrevY = prevY;
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prevX = x3;
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prevY = y3;
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ii = 0;
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}
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}
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}
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// Remove empty polygons that resulted from the merge step above.
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for (int i = convexPolygons.Count - 1; i >= 0; i--) {
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polygon = convexPolygons.Items[i];
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if (polygon.Count == 0) {
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convexPolygons.RemoveAt(i);
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polygonPool.Free(polygon);
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polygonIndices = convexPolygonsIndices.Items[i];
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convexPolygonsIndices.RemoveAt(i);
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polygonIndicesPool.Free(polygonIndices);
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}
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}
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return convexPolygons;
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}
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static private bool IsConcave (int index, int vertexCount, float[] vertices, int[] indices) {
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int previous = indices[(vertexCount + index - 1) % vertexCount] << 1;
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int current = indices[index] << 1;
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int next = indices[(index + 1) % vertexCount] << 1;
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return !PositiveArea(vertices[previous], vertices[previous + 1], vertices[current], vertices[current + 1], vertices[next],
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vertices[next + 1]);
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}
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static private bool PositiveArea (float p1x, float p1y, float p2x, float p2y, float p3x, float p3y) {
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return p1x * (p3y - p2y) + p2x * (p1y - p3y) + p3x * (p2y - p1y) >= 0;
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}
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static private int Winding (float p1x, float p1y, float p2x, float p2y, float p3x, float p3y) {
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float px = p2x - p1x, py = p2y - p1y;
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return p3x * py - p3y * px + px * p1y - p1x * py >= 0 ? 1 : -1;
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}
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}
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}
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