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package com.sun.opengl.impl.glu.nurbs;
/*
** License Applicability. Except to the extent portions of this file are
** made subject to an alternative license as permitted in the SGI Free
** Software License B, Version 1.1 (the "License"), the contents of this
** file are subject only to the provisions of the License. You may not use
** this file except in compliance with the License. You may obtain a copy
** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
**
** http://oss.sgi.com/projects/FreeB
**
** Note that, as provided in the License, the Software is distributed on an
** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
**
** Original Code. The Original Code is: OpenGL Sample Implementation,
** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
** Copyright in any portions created by third parties is as indicated
** elsewhere herein. All Rights Reserved.
**
** Additional Notice Provisions: The application programming interfaces
** established by SGI in conjunction with the Original Code are The
** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
** Window System(R) (Version 1.3), released October 19, 1998. This software
** was created using the OpenGL(R) version 1.2.1 Sample Implementation
** published by SGI, but has not been independently verified as being
** compliant with the OpenGL(R) version 1.2.1 Specification.
*/
/**
* Knot vector used in curve specification
*
* @author Tomas Hrasky
*
*/
public class Knotvector {
/**
* Tolerance used when comparing knots - when difference is smaller, knots
* are considered equal
*/
public static final float TOLERANCE = 1.0e-5f;
/**
* Maximum curve order
*/
private static final int MAXORDER = 24;
/**
* Number of knots
*/
int knotcount;
/**
* Number of control points' coordinates
*/
int stride;
/**
* Curve order
*/
int order;
/**
* Knots
*/
float[] knotlist;
/**
* Makes new knotvector
*
* @param nknots
* number of knots
* @param stride
* number of ctrl points' corrdinates
* @param order
* curve order
* @param knot
* knots
*/
public Knotvector(int nknots, int stride, int order, float[] knot) {
// DONE
init(nknots, stride, order, knot);
}
/**
* Initializes knotvector
*
* @param nknots
* number of knots
* @param stride
* number of ctrl points' corrdinates
* @param order
* curve order
* @param knot
* knots
*/
public void init(int nknots, int stride, int order, float[] knot) {
// DONE
this.knotcount = nknots;
this.stride = stride;
this.order = order;
this.knotlist = new float[nknots];
for (int i = 0; i < nknots; i++) {
this.knotlist[i] = knot[i];
}
}
/**
* Validates knot vector parameters
*
* @return knot vector validity
*/
public int validate() {
int kindex = knotcount - 1;
if (order < 1 || order > MAXORDER) {
return 1;
}
if (knotcount < 2 * order) {
return 2;
}
if (identical(knotlist[kindex - (order - 1)], knotlist[order - 1])) {
return 3;
}
for (int i = 0; i < kindex; i++) {
if (knotlist[i] > knotlist[i + 1])
return 4;
}
int multi = 1;
for (; kindex >= 1; kindex--) {
if (knotlist[kindex] - knotlist[kindex - 1] < TOLERANCE) {
multi++;
continue;
}
if (multi > order) {
return 5;
}
multi = 1;
}
if (multi > order) {
return 5;
}
return 0;
}
/**
* Show specified message
*
* @param msg
* message to be shown
*/
public void show(String msg) {
// TODO Auto-generated method stub
// System.out.println("TODO knotvector.show");
}
/**
* Compares two knots for equality
*
* @param a
* first knot
* @param b
* second knot
* @return knots are/are not equal
*/
public static boolean identical(float a, float b) {
return ((a - b) < TOLERANCE) ? true : false;
}
}
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