Kirill Vainer
9 years ago
commit
f9500f955f
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/* |
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* Copyright (c) 2009-2015 jMonkeyEngine |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions are |
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* met: |
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* |
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* * Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* * Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* * Neither the name of 'jMonkeyEngine' nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package com.jme3.scene.plugins.triangulator; |
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|
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import com.jme3.math.FastMath; |
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import com.jme3.math.Matrix3f; |
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import com.jme3.math.Vector2f; |
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import com.jme3.math.Vector3f; |
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import com.jme3.scene.plugins.IrPolygon; |
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import com.jme3.scene.plugins.IrVertex; |
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import java.util.ArrayList; |
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|
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/** |
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* Implemented according to |
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* <ul> |
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* <li>http://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf</li>
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* <li>http://cgm.cs.mcgill.ca/~godfried/teaching/cg-projects/97/Ian/algorithm2.html</li>
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* </ul> |
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*/ |
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public final class EarClippingTriangulator { |
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private static enum VertexType { |
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Convex, |
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Reflex, |
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Ear; |
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} |
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private final ArrayList<Integer> indices = new ArrayList<Integer>(); |
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private final ArrayList<VertexType> types = new ArrayList<VertexType>(); |
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private final ArrayList<Vector2f> positions = new ArrayList<Vector2f>(); |
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|
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public EarClippingTriangulator() { |
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} |
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private static int ccw(Vector2f p0, Vector2f p1, Vector2f p2) { |
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float result = (p1.x - p0.x) * (p2.y - p1.y) - (p1.y - p0.y) * (p2.x - p1.x); |
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if (result > 0) { |
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return 1; |
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} else if (result < 0) { |
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return -1; |
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} else { |
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return 0; |
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} |
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} |
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|
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private static boolean pointInTriangle(Vector2f t0, Vector2f t1, Vector2f t2, Vector2f p) { |
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float d = ((t1.y - t2.y) * (t0.x - t2.x) + (t2.x - t1.x) * (t0.y - t2.y)); |
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float a = ((t1.y - t2.y) * (p.x - t2.x) + (t2.x - t1.x) * (p.y - t2.y)) / d; |
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float b = ((t2.y - t0.y) * (p.x - t2.x) + (t0.x - t2.x) * (p.y - t2.y)) / d; |
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float c = 1 - a - b; |
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return 0 <= a && a <= 1 && 0 <= b && b <= 1 && 0 <= c && c <= 1; |
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} |
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|
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private static Matrix3f normalToMatrix(Vector3f norm) { |
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Vector3f tang1 = norm.cross(Vector3f.UNIT_X); |
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if (tang1.lengthSquared() < FastMath.ZERO_TOLERANCE) { |
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tang1 = norm.cross(Vector3f.UNIT_Y); |
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} |
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tang1.normalizeLocal(); |
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Vector3f tang2 = norm.cross(tang1).normalizeLocal(); |
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return new Matrix3f( |
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tang1.x, tang1.y, tang1.z, |
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tang2.x, tang2.y, tang2.z, |
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norm.x, norm.y, norm.z); |
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} |
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|
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private int prev(int index) { |
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if (index == 0) { |
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return indices.size() - 1; |
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} else { |
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return index - 1; |
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} |
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} |
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private int next(int index) { |
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if (index == indices.size() - 1) { |
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return 0; |
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} else { |
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return index + 1; |
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} |
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} |
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private VertexType calcType(int index) { |
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int prev = prev(index); |
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int next = next(index); |
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Vector2f p0 = positions.get(prev); |
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Vector2f p1 = positions.get(index); |
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Vector2f p2 = positions.get(next); |
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if (ccw(p0, p1, p2) <= 0) { |
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return VertexType.Reflex; |
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} else { |
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for (int i = 0; i < positions.size() - 3; i++) { |
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int testIndex = (index + 2 + i) % positions.size(); |
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if (types.get(testIndex) != VertexType.Reflex) { |
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continue; |
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} |
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Vector2f p = positions.get(testIndex); |
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if (pointInTriangle(p0, p1, p2, p)) { |
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return VertexType.Convex; |
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} |
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} |
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return VertexType.Ear; |
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} |
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} |
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private void updateType(int index) { |
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if (types.get(index) == VertexType.Convex) { |
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return; |
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} |
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types.set(index, calcType(index)); |
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} |
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private void loadVertices(IrVertex[] vertices) { |
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indices.ensureCapacity(vertices.length); |
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types.ensureCapacity(vertices.length); |
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positions.ensureCapacity(vertices.length); |
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Vector3f normal = FastMath.computeNormal( |
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vertices[0].pos, |
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vertices[1].pos, |
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vertices[2].pos); |
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Matrix3f transform = normalToMatrix(normal); |
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for (int i = 0; i < vertices.length; i++) { |
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Vector3f projected = transform.mult(vertices[i].pos); |
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indices.add(i); |
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positions.add(new Vector2f(projected.x, projected.y)); |
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types.add(VertexType.Reflex); |
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} |
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for (int i = 0; i < vertices.length; i++) { |
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types.set(i, calcType(i)); |
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} |
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} |
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private IrPolygon createTriangle(IrPolygon polygon, int prev, int index, int next) { |
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int p0 = indices.get(prev); |
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int p1 = indices.get(index); |
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int p2 = indices.get(next); |
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IrPolygon triangle = new IrPolygon(); |
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triangle.vertices = new IrVertex[] { |
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polygon.vertices[p0], |
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polygon.vertices[p1], |
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polygon.vertices[p2], |
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}; |
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return triangle; |
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} |
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/** |
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* Triangulates the given polygon. |
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* |
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* Five or more vertices are required, if less are given, an exception |
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* is thrown. |
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* |
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* @param polygon The polygon to triangulate. |
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* @return N - 2 triangles, where N is the number of vertices in the polygon. |
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* |
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* @throws IllegalArgumentException If the polygon has less than 5 vertices. |
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*/ |
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public IrPolygon[] triangulate(IrPolygon polygon) { |
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if (polygon.vertices.length < 5) { |
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throw new IllegalArgumentException("Only polygons with 5 or more vertices are supported"); |
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} |
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try { |
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int numTris = 0; |
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IrPolygon[] triangles = new IrPolygon[polygon.vertices.length - 2]; |
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loadVertices(polygon.vertices); |
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int index = 0; |
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while (types.size() > 3) { |
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if (types.get(index) == VertexType.Ear) { |
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int prev = prev(index); |
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int next = next(index); |
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triangles[numTris++] = createTriangle(polygon, prev, index, next); |
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indices.remove(index); |
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types.remove(index); |
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positions.remove(index); |
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next = next(prev); |
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updateType(prev); |
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updateType(next); |
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index = next(next); |
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} else { |
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index = next(index); |
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} |
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} |
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if (types.size() == 3) { |
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triangles[numTris++] = createTriangle(polygon, 0, 1, 2); |
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} |
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if (numTris != triangles.length) { |
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throw new AssertionError("Triangulation failed to generate enough triangles"); |
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} |
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return triangles; |
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} finally { |
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indices.clear(); |
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positions.clear(); |
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types.clear(); |
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} |
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} |
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} |
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@ -0,0 +1,64 @@ |
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/* |
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* Copyright (c) 2009-2015 jMonkeyEngine |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
||||
* modification, are permitted provided that the following conditions are |
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* met: |
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* |
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* * Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* * Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* * Neither the name of 'jMonkeyEngine' nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
||||
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
||||
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
||||
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
||||
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package com.jme3.scene.plugins.triangulator; |
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|
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import com.jme3.math.Vector3f; |
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import com.jme3.scene.plugins.IrPolygon; |
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import com.jme3.scene.plugins.IrVertex; |
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import junit.framework.TestCase; |
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public class TriangulatorTest extends TestCase { |
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public void testTriangulator() { |
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Vector3f[] dataSet = new Vector3f[]{ |
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new Vector3f(0.75f, 0.3f, 1.2f), |
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new Vector3f(0.75f, 0.3f, 0.0f), |
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new Vector3f(0.75f, 0.17f, 0.0f), |
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new Vector3f(0.75000095f, 0.17f, 1.02f), |
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new Vector3f(0.75f, -0.17f, 1.02f), |
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new Vector3f(0.75f, -0.17f, 0.0f), |
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new Vector3f(0.75f, -0.3f, 0.0f), |
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new Vector3f(0.75f, -0.3f, 1.2f) |
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}; |
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IrPolygon poly = new IrPolygon(); |
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poly.vertices = new IrVertex[dataSet.length]; |
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for (int i = 0; i < dataSet.length; i++) { |
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poly.vertices[i] = new IrVertex(); |
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poly.vertices[i].pos = dataSet[i]; |
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} |
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EarClippingTriangulator triangulator = new EarClippingTriangulator(); |
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triangulator.triangulate(poly); |
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} |
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|
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} |
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