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Utility functions for the Java 3D Graphics API
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/*
* Copyright (c) 2007 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistribution of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistribution in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any
* kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
* WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
* EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
* NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
* USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
* ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
* CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
* REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
* INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or
* intended for use in the design, construction, operation or
* maintenance of any nuclear facility.
*
*/
// ----------------------------------------------------------------------
//
// The reference to Fast Industrial Strength Triangulation (FIST) code
// in this release by Sun Microsystems is related to Sun's rewrite of
// an early version of FIST. FIST was originally created by Martin
// Held and Joseph Mitchell at Stony Brook University and is
// incorporated by Sun under an agreement with The Research Foundation
// of SUNY (RFSUNY). The current version of FIST is available for
// commercial use under a license agreement with RFSUNY on behalf of
// the authors and Stony Brook University. Please contact the Office
// of Technology Licensing at Stony Brook, phone 631-632-9009, for
// licensing information.
//
// ----------------------------------------------------------------------
package org.scijava.java3d.utils.geometry;
class Orientation {
/**
* determine the outer polygon and the orientation of the polygons; the
* default orientation is CCW for the outer-most polygon, and CW for the
* inner polygons. the polygonal loops are referenced by loops[i1,..,i2-1].
*/
static void adjustOrientation(Triangulator triRef, int i1, int i2) {
double area;
int i, outer;
int ind;
if(i1 >= i2)
System.out.println("Orientation:adjustOrientation Problem i1>=i2 !!!");
if (triRef.numLoops >= triRef.maxNumPolyArea) {
// System.out.println("Orientation:adjustOrientation Expanding polyArea array .");
triRef.maxNumPolyArea = triRef.numLoops;
double old[] = triRef.polyArea;
triRef.polyArea = new double[triRef.maxNumPolyArea];
if(old != null)
System.arraycopy(old, 0, triRef.polyArea, 0, old.length);
}
// for each contour, compute its signed area, i.e., its orientation. the
// contour with largest area is assumed to be the outer-most contour.
for (i = i1; i < i2; ++i) {
ind = triRef.loops[i];
triRef.polyArea[i] = polygonArea(triRef, ind);
}
// determine the outer-most contour
area = Math.abs(triRef.polyArea[i1]);
outer = i1;
for (i = i1 + 1; i < i2; ++i) {
if (area < Math.abs(triRef.polyArea[i])) {
area = Math.abs(triRef.polyArea[i]);
outer = i;
}
}
// default: the outer contour is referenced by loops[i1]
if (outer != i1) {
ind = triRef.loops[i1];
triRef.loops[i1] = triRef.loops[outer];
triRef.loops[outer] = ind;
area = triRef.polyArea[i1];
triRef.polyArea[i1] = triRef.polyArea[outer];
triRef.polyArea[outer] = area;
}
// adjust the orientation
if (triRef.polyArea[i1] < 0.0) triRef.swapLinks(triRef.loops[i1]);
for (i = i1 + 1; i < i2; ++i) {
if (triRef.polyArea[i] > 0.0) triRef.swapLinks(triRef.loops[i]);
}
}
/**
* This function computes twice the signed area of a simple closed polygon.
*/
static double polygonArea(Triangulator triRef, int ind) {
int hook = 0;
int ind1, ind2;
int i1, i2;
double area = 0.0, area1 = 0;
ind1 = ind;
i1 = triRef.fetchData(ind1);
ind2 = triRef.fetchNextData(ind1);
i2 = triRef.fetchData(ind2);
area = Numerics.stableDet2D(triRef, hook, i1, i2);
ind1 = ind2;
i1 = i2;
while (ind1 != ind) {
ind2 = triRef.fetchNextData(ind1);
i2 = triRef.fetchData(ind2);
area1 = Numerics.stableDet2D(triRef, hook, i1, i2);
area += area1;
ind1 = ind2;
i1 = i2;
}
return area;
}
/**
* Determine the orientation of the polygon. The default orientation is CCW.
*/
static void determineOrientation(Triangulator triRef, int ind) {
double area;
// compute the polygon's signed area, i.e., its orientation.
area = polygonArea(triRef, ind);
// adjust the orientation (i.e., make it CCW)
if (area < 0.0) {
triRef.swapLinks(ind);
triRef.ccwLoop = false;
}
}
}
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