/*
* gleem -- OpenGL Extremely Easy-To-Use Manipulators.
* Copyright (C) 1998-2003 Kenneth B. Russell (kbrussel@alum.mit.edu)
*
* Copying, distribution and use of this software in source and binary
* forms, with or without modification, is permitted provided that the
* following conditions are met:
*
* Distributions of source code must reproduce the copyright notice,
* this list of conditions and the following disclaimer in the source
* code header files; and Distributions of binary code must reproduce
* the copyright notice, this list of conditions and the following
* disclaimer in the documentation, Read me file, license file and/or
* other materials provided with the software distribution.
*
* The names of Sun Microsystems, Inc. ("Sun") and/or the copyright
* holder may not 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, NON-INTERFERENCE, ACCURACY OF
* INFORMATIONAL CONTENT OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. THE
* COPYRIGHT HOLDER, SUN AND SUN'S LICENSORS SHALL NOT BE LIABLE FOR
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* REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
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* OPERATION OR MAINTENANCE OF ANY NUCLEAR FACILITY. THE COPYRIGHT
* HOLDER, SUN AND SUN'S LICENSORS DISCLAIM ANY EXPRESS OR IMPLIED
* WARRANTY OF FITNESS FOR SUCH USES.
*/
package gleem.linalg;
/** 3x3 matrix class useful for simple linear algebra. Representation
is (as Mat4f) in row major order and assumes multiplication by
column vectors on the right. */
public class Mat3f {
private float[] data;
/** Creates new matrix initialized to the zero matrix */
public Mat3f() {
data = new float[9];
}
/** Initialize to the identity matrix. */
public void makeIdent() {
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
if (i == j) {
set(i, j, 1.0f);
} else {
set(i, j, 0.0f);
}
}
}
}
/** Gets the (i,j)th element of this matrix, where i is the row
index and j is the column index */
public float get(int i, int j) {
return data[3 * i + j];
}
/** Sets the (i,j)th element of this matrix, where i is the row
index and j is the column index */
public void set(int i, int j, float val) {
data[3 * i + j] = val;
}
/** Set column i (i=[0..2]) to vector v. */
public void setCol(int i, Vec3f v) {
set(0, i, v.x());
set(1, i, v.y());
set(2, i, v.z());
}
/** Set row i (i=[0..2]) to vector v. */
public void setRow(int i, Vec3f v) {
set(i, 0, v.x());
set(i, 1, v.y());
set(i, 2, v.z());
}
/** Transpose this matrix in place. */
public void transpose() {
float t;
t = get(0, 1);
set(0, 1, get(1, 0));
set(1, 0, t);
t = get(0, 2);
set(0, 2, get(2, 0));
set(2, 0, t);
t = get(1, 2);
set(1, 2, get(2, 1));
set(2, 1, t);
}
/** Return the determinant. Computed across the zeroth row. */
public float determinant() {
return (get(0, 0) * (get(1, 1) * get(2, 2) - get(2, 1) * get(1, 2)) +
get(0, 1) * (get(2, 0) * get(1, 2) - get(1, 0) * get(2, 2)) +
get(0, 2) * (get(1, 0) * get(2, 1) - get(2, 0) * get(1, 1)));
}
/** Full matrix inversion in place. If matrix is singular, returns
false and matrix contents are untouched. If you know the matrix
is orthonormal, you can call transpose() instead. */
public boolean invert() {
float det = determinant();
if (det == 0.0f)
return false;
// Form cofactor matrix
Mat3f cf = new Mat3f();
cf.set(0, 0, get(1, 1) * get(2, 2) - get(2, 1) * get(1, 2));
cf.set(0, 1, get(2, 0) * get(1, 2) - get(1, 0) * get(2, 2));
cf.set(0, 2, get(1, 0) * get(2, 1) - get(2, 0) * get(1, 1));
cf.set(1, 0, get(2, 1) * get(0, 2) - get(0, 1) * get(2, 2));
cf.set(1, 1, get(0, 0) * get(2, 2) - get(2, 0) * get(0, 2));
cf.set(1, 2, get(2, 0) * get(0, 1) - get(0, 0) * get(2, 1));
cf.set(2, 0, get(0, 1) * get(1, 2) - get(1, 1) * get(0, 2));
cf.set(2, 1, get(1, 0) * get(0, 2) - get(0, 0) * get(1, 2));
cf.set(2, 2, get(0, 0) * get(1, 1) - get(1, 0) * get(0, 1));
// Now copy back transposed
for (int i = 0; i < 3; i++)
for (int j = 0; j < 3; j++)
set(i, j, cf.get(j, i) / det);
return true;
}
/** Multiply a 3D vector by this matrix. NOTE: src and dest must be
different vectors. */
public void xformVec(Vec3f src, Vec3f dest) {
dest.set(get(0, 0) * src.x() +
get(0, 1) * src.y() +
get(0, 2) * src.z(),
get(1, 0) * src.x() +
get(1, 1) * src.y() +
get(1, 2) * src.z(),
get(2, 0) * src.x() +
get(2, 1) * src.y() +
get(2, 2) * src.z());
}
/** Returns this * b; creates new matrix */
public Mat3f mul(Mat3f b) {
Mat3f tmp = new Mat3f();
tmp.mul(this, b);
return tmp;
}
/** this = a * b */
public void mul(Mat3f a, Mat3f b) {
for (int rc = 0; rc < 3; rc++)
for (int cc = 0; cc < 3; cc++) {
float tmp = 0.0f;
for (int i = 0; i < 3; i++)
tmp += a.get(rc, i) * b.get(i, cc);
set(rc, cc, tmp);
}
}
public Matf toMatf() {
Matf out = new Matf(3, 3);
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
out.set(i, j, get(i, j));
}
}
return out;
}
public String toString() {
String endl = System.getProperty("line.separator");
return "(" +
get(0, 0) + ", " + get(0, 1) + ", " + get(0, 2) + endl +
get(1, 0) + ", " + get(1, 1) + ", " + get(1, 2) + endl +
get(2, 0) + ", " + get(2, 1) + ", " + get(2, 2) + ")";
}
}