/** an affine transform; all operations are destructive */
public final class Affine {
- // [ a b e ]
- // [ c d f ]
+ // [ a c e ]
+ // [ b d f ]
// [ 0 0 1 ]
public float a, b, c, d, e, f;
return new Affine(c, s, -s, c, 0, 0);
}
- /** this = this * a */
- public Affine multiply(Affine A) {
+ /** this = a * this */
+ public Affine premultiply(Affine A) {
float _a = this.a * A.a + this.b * A.c;
float _b = this.a * A.b + this.b * A.d;
float _c = this.c * A.a + this.d * A.c;
return this;
}
- /** this = a * this */
- public Affine premultiply(Affine A) {
+ /** this = this * a */
+ public Affine multiply(Affine A) {
float _a = A.a * this.a + A.b * this.c;
float _b = A.a * this.b + A.b * this.d;
float _c = A.c * this.a + A.d * this.c;
}
public Affine invert() {
- float det = 1 / (a * d - b * c);
- float _a = d * det;
- float _b = -1 * b * det;
- float _c = -1 * c * det;
- float _d = a * det;
- float _e = -1 * e * a - f * c;
- float _f = -1 * e * b - f * d;
+ float det = (a * d - b * c);
+ float _a = d / det;
+ float _b = -1 * b / det;
+ float _c = -1 * c / det;
+ float _d = a / det;
+ float _e = (f*c-e*d)/det;
+ float _f = (b*e-a*f)/det;
a = _a; b = _b; c = _c; d = _d; e = _e; f = _f;
return this;
}