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Java implementation of BSP based CSG (Constructive Solid Geometry)
/*
* Copyright John E. Lloyd, 2003. All rights reserved. Permission
* to use, copy, and modify, without fee, is granted for non-commercial
* and research purposes, provided that this copyright notice appears
* in all copies.
*
* This software is distributed "as is", without any warranty, including
* any implied warranty of merchantability or fitness for a particular
* use. The authors assume no responsibility for, and shall not be liable
* for, any special, indirect, or consequential damages, or any damages
* whatsoever, arising out of or in connection with the use of this
* software.
*/
package eu.mihosoft.vrl.v3d.ext.quickhull3d;
/**
* Represents the half-edges that surround each
* face in a counter-clockwise direction.
*
* @author John E. Lloyd, Fall 2004 */
class HalfEdge
{
/**
* The vertex associated with the head of this half-edge.
*/
Vertex vertex;
/**
* Triangular face associated with this half-edge.
*/
Face face;
/**
* Next half-edge in the triangle.
*/
HalfEdge next;
/**
* Previous half-edge in the triangle.
*/
HalfEdge prev;
/**
* Half-edge associated with the opposite triangle
* adjacent to this edge.
*/
HalfEdge opposite;
/**
* Constructs a HalfEdge with head vertex v and
* left-hand triangular face f.
*
* @param v head vertex
* @param f left-hand triangular face
*/
public HalfEdge (Vertex v, Face f)
{
vertex = v;
face = f;
}
public HalfEdge ()
{
}
/**
* Sets the value of the next edge adjacent
* (counter-clockwise) to this one within the triangle.
*
* @param edge next adjacent edge */
public void setNext (HalfEdge edge)
{
next = edge;
}
/**
* Gets the value of the next edge adjacent
* (counter-clockwise) to this one within the triangle.
*
* @return next adjacent edge */
public HalfEdge getNext()
{
return next;
}
/**
* Sets the value of the previous edge adjacent (clockwise) to
* this one within the triangle.
*
* @param edge previous adjacent edge */
public void setPrev (HalfEdge edge)
{
prev = edge;
}
/**
* Gets the value of the previous edge adjacent (clockwise) to
* this one within the triangle.
*
* @return previous adjacent edge
*/
public HalfEdge getPrev()
{
return prev;
}
/**
* Returns the triangular face located to the left of this
* half-edge.
*
* @return left-hand triangular face
*/
public Face getFace()
{
return face;
}
/**
* Returns the half-edge opposite to this half-edge.
*
* @return opposite half-edge
*/
public HalfEdge getOpposite()
{
return opposite;
}
/**
* Sets the half-edge opposite to this half-edge.
*
* @param edge opposite half-edge
*/
public void setOpposite (HalfEdge edge)
{
opposite = edge;
edge.opposite = this;
}
/**
* Returns the head vertex associated with this half-edge.
*
* @return head vertex
*/
public Vertex head()
{
return vertex;
}
/**
* Returns the tail vertex associated with this half-edge.
*
* @return tail vertex
*/
public Vertex tail()
{
return prev != null ? prev.vertex : null;
}
/**
* Returns the opposite triangular face associated with this
* half-edge.
*
* @return opposite triangular face
*/
public Face oppositeFace()
{
return opposite != null ? opposite.face : null;
}
/**
* Produces a string identifying this half-edge by the point
* index values of its tail and head vertices.
*
* @return identifying string
*/
public String getVertexString()
{
if (tail() != null)
{ return "" +
tail().index + "-" +
head().index;
}
else
{ return "?-" + head().index;
}
}
/**
* Returns the length of this half-edge.
*
* @return half-edge length
*/
public double length()
{
if (tail() != null)
{ return head().pnt.distance(tail().pnt);
}
else
{ return -1;
}
}
/**
* Returns the length squared of this half-edge.
*
* @return half-edge length squared
*/
public double lengthSquared()
{
if (tail() != null)
{ return head().pnt.distanceSquared(tail().pnt);
}
else
{ return -1;
}
}
// /**
// * Computes nrml . (del0 X del1), where del0 and del1
// * are the direction vectors along this halfEdge, and the
// * halfEdge he1.
// *
// * A product > 0 indicates a left turn WRT the normal
// */
// public double turnProduct (HalfEdge he1, Vector3d nrml)
// {
// Point3d pnt0 = tail().pnt;
// Point3d pnt1 = head().pnt;
// Point3d pnt2 = he1.head().pnt;
// double del0x = pnt1.x - pnt0.x;
// double del0y = pnt1.y - pnt0.y;
// double del0z = pnt1.z - pnt0.z;
// double del1x = pnt2.x - pnt1.x;
// double del1y = pnt2.y - pnt1.y;
// double del1z = pnt2.z - pnt1.z;
// return (nrml.x*(del0y*del1z - del0z*del1y) +
// nrml.y*(del0z*del1x - del0x*del1z) +
// nrml.z*(del0x*del1y - del0y*del1x));
// }
}