public static Face makeCcw(Face f, Edge e, Vertex p) { int i; Face invisibleFace; if (e.getAdjface(1) == null) { invisibleFace = e.getAdjface(0); } else { if (!e.getAdjface(0).visible) { invisibleFace = e.getAdjface(0); } else { invisibleFace = e.getAdjface(1); } } for (i = 0; invisibleFace.getVertex(i) != e.getEndpt(1); i++) {} if (invisibleFace.getVertex((i + 1) % 3) != e.getEndpt(0)) { f.setVertex(0, e.getEndpt(1)); f.setVertex(1, e.getEndpt(0)); } else { f.setVertex(0, e.getEndpt(0)); f.setVertex(1, e.getEndpt(1)); swap(f.getEdge(1), f.getEdge(2)); } f.setVertex(2, p); return f; }
public static void buildTetrahedron() { QueueElement<Vertex> v0; QueueElement<Vertex> v3; int volume; // find 3 noncollinear points v0 = ConvexHull.vertices.getFirst(); while (collinear(v0.getElem(), v0.getNext().getElem(), v0.getNext().getNext().getElem())) { v0 = v0.getNext(); if (v0.getNext() == ConvexHull.vertices.getFirst()) { System.err.println("All points are collinear"); System.exit(0); } } // mark vertices as processed v0.getElem().setMark(true); v0.getNext().getElem().setMark(true); v0.getNext().getNext().getElem().setMark(true); Edge e0 = Edge.makeEdge(v0.getElem(), v0.getNext().getElem()); Edge e1 = Edge.makeEdge(v0.getNext().getElem(), v0.getNext().getNext().getElem()); Edge e2 = Edge.makeEdge(v0.getNext().getNext().getElem(), v0.getElem()); Face f = Face.makeFace(e0, e1, e2); f.setVertices(v0.getElem(), v0.getNext().getElem(), v0.getNext().getNext().getElem()); e0.setAdjface(0, f); e1.setAdjface(0, f); e1.setAdjface(0, f); // try to find another noncollinear vertex v3 = v0.getNext().getNext().getNext(); volume = volume(f, v3.getElem()); while (volume == 0) { v3 = v3.getNext(); if (v3 == ConvexHull.vertices.getFirst()) { System.err.println("All points are coplanar"); System.exit(0); } volume = volume(f, v3.getElem()); } v3.getElem().setMark(true); // store vertices in ccw order if (volume < 0) { swap(f.getVertex(1), f.getVertex(2)); swap(f.getEdge(1), f.getEdge(2)); } e0.setAdjface(1, makeStructs(e0, v3.getElem())); e1.setAdjface(1, makeStructs(e1, v3.getElem())); e2.setAdjface(1, makeStructs(e2, v3.getElem())); Cleaning.cleanUp(); }
private static int volume(Face f, Vertex p) { double ax = f.getVertex(0).getCoordinate(0) - p.getCoordinate(0); double ay = f.getVertex(0).getCoordinate(1) - p.getCoordinate(1); double az = f.getVertex(0).getCoordinate(2) - p.getCoordinate(2); double bx = f.getVertex(1).getCoordinate(0) - p.getCoordinate(0); double by = f.getVertex(1).getCoordinate(1) - p.getCoordinate(1); double bz = f.getVertex(1).getCoordinate(2) - p.getCoordinate(2); double cx = f.getVertex(2).getCoordinate(0) - p.getCoordinate(0); double cy = f.getVertex(2).getCoordinate(1) - p.getCoordinate(1); double cz = f.getVertex(2).getCoordinate(2) - p.getCoordinate(2); double volume = ax * (by * cz - bz * cy) + ay * (bz * cx - bx * cz) + az * (bx * cy - by * cx); if (volume > 0.5) { return 1; } else if (volume < -0.5) { return -1; } else { return 0; } }