while developing simulator I found couple of small bugs in dyn4j library
1. Rectangle class in Geometry package
Code: Select all
/**
* Returns the rotation about the local center in radians.
* @return double the rotation in radians
* @since 3.0.1
*/
public double getRotation() {
// when the shape is created normals[1] will always be the positive x-axis
// we can get the rotation by comparing it to the positive x-axis
// since the normal vectors are rotated with the vertices when
// a shape is rotated
// return this.normals[1].getAngleBetween(Vector2.X_AXIS); //original
return -this.normals[1].getAngleBetween(Vector2.X_AXIS); //corrected
}
2. Polygon Class in Geometry package
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@Override
public void rotate(double theta, double x, double y) {
super.rotate(theta, x, y);
int size = this.vertices.length;
for (int i = 0; i < size; i++) {
this.vertices[i].rotate(theta, x, y);
// this.normals[i].rotate(theta, x,y);//original
this.normals[i].rotate(theta); //corrected==>normals are not supposed to be rotated about point
}
}These bugs create problem in multi-fixture body with fixture as rectangle rotated by some angle. The angle of rotation is then calculated about wrongly transformed normals.
Anyway Dyn4j is one of the best thing I learnt so far.
Regards..
since I was doing these the right way in some other shape classes....