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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 or intended for use
* in the design, construction, operation or maintenance of any nuclear
* facility.
*
*/
package net.java.joglutils.msg.math;
/** 2x2 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 Mat2f {
private float[] data;
/** Creates new matrix initialized to the zero matrix */
public Mat2f() {
data = new float[4];
}
/** Initialize to the identity matrix. */
public void makeIdent() {
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 2; 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[2 * 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[2 * i + j] = val;
}
/** Set column i (i=[0..1]) to vector v. */
public void setCol(int i, Vec2f v) {
set(0, i, v.x());
set(1, i, v.y());
}
/** Set row i (i=[0..1]) to vector v. */
public void setRow(int i, Vec2f v) {
set(i, 0, v.x());
set(i, 1, v.y());
}
/** Transpose this matrix in place. */
public void transpose() {
float t = get(0, 1);
set(0, 1, get(1, 0));
set(1, 0, t);
}
/** Return the determinant. */
public float determinant() {
return (get(0, 0) * get(1, 1) - get(1, 0) * get(0, 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;
// Create transpose of cofactor matrix in place
float t = get(0, 0);
set(0, 0, get(1, 1));
set(1, 1, t);
set(0, 1, -get(0, 1));
set(1, 0, -get(1, 0));
// Now divide by determinant
for (int i = 0; i < 4; i++) {
data[i] /= det;
}
return true;
}
/** Multiply a 2D vector by this matrix. NOTE: src and dest must be
different vectors. */
public void xformVec(Vec2f src, Vec2f dest) {
dest.set(get(0, 0) * src.x() +
get(0, 1) * src.y(),
get(1, 0) * src.x() +
get(1, 1) * src.y());
}
/** Returns this * b; creates new matrix */
public Mat2f mul(Mat2f b) {
Mat2f tmp = new Mat2f();
tmp.mul(this, b);
return tmp;
}
/** this = a * b */
public void mul(Mat2f a, Mat2f b) {
for (int rc = 0; rc < 2; rc++)
for (int cc = 0; cc < 2; cc++) {
float tmp = 0.0f;
for (int i = 0; i < 2; i++)
tmp += a.get(rc, i) * b.get(i, cc);
set(rc, cc, tmp);
}
}
public Matf toMatf() {
Matf out = new Matf(2, 2);
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 2; 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) + endl +
get(1, 0) + ", " + get(1, 1) + ")";
}
}
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