/* ===========================================================
* Orson Charts : a 3D chart library for the Java(tm) platform
* ===========================================================
*
* (C)opyright 2013-2016, by Object Refinery Limited. All rights reserved.
*
* http://www.object-refinery.com/orsoncharts/index.html
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
* Other names may be trademarks of their respective owners.]
*
* If you do not wish to be bound by the terms of the GPL, an alternative
* commercial license can be purchased. For details, please see visit the
* Orson Charts home page:
*
* http://www.object-refinery.com/orsoncharts/index.html
*
*/
package com.orsoncharts.graphics3d;
/**
* A collection of utility methods for 3D geometry.
*/
public class Utils3D {
private Utils3D() {
// no need to instantiate this class
}
/**
* Returns the length of the vector v.
*
* @param v the vector ({@code null} not permitted).
*
* @return The length.
*/
public static double length(Point3D v) {
return Math.sqrt(v.x * v.x + v.y * v.y + v.z * v.z);
}
/**
* Returns a new vector that is the normalised form of the specified
* vector.
*
* @param v the vector ({@code null} not permitted).
*
* @return The normalised form of the specified vector.
*
* @since 1.2
*/
public static Point3D normalise(Point3D v) {
double length = length(v);
return new Point3D(v.x / length, v.y / length, v.z / length);
}
/**
* Returns the scalar product of two vectors.
*
* @param a vector A ({@code null} not permitted).
* @param b vector B ({@code null} not permitted).
*
* @return The scalar product.
*/
public static double scalarprod(Point3D a, Point3D b) {
return a.x * b.x + a.y * b.y + a.z * b.z;
}
/**
* Returns the normal vector for the plane defined by three points.
*
* @param a point A ({@code null} not permitted).
* @param b point B ({@code null} not permitted).
* @param c point C ({@code null} not permitted).
*
* @return The normal vector.
*/
public static Point3D normal(Point3D a, Point3D b, Point3D c) {
double ax = a.x - c.x;
double ay = a.y - c.y;
double az = a.z - c.z;
double bx = b.x - c.x;
double by = b.y - c.y;
double bz = b.z - c.z;
return new Point3D(ay * bz - az * by, az * bx - ax * bz,
ax * by - ay * bx);
}
/**
* Returns the angle between the two vectors.
*
* @param a vector A ({@code null} not permitted).
* @param b vector B ({@code null} not permitted).
*
* @return The (positive) angle in radians.
*/
public static double angle(Point3D a, Point3D b) {
double dp = a.x * b.x + a.y * b.y + a.z * b.z;
double alen = length(a);
double blen = length(b);
double c = dp / (alen * blen);
// rounding can cause abs(c) to be greater than one, let's sweep that
// under the carpet...
c = Math.max(-1.0, Math.min(1.0, c));
return Math.acos(c);
}
}