/**
* Set the view matrix `s' is the scaling factor of translating real coordinates to the screen
* coordinates (x0, y0) the screen coordinates of the center
*/
void setMatrix(Matrix3D viewMat, double s, double x0, double y0) {
mat.unit();
mat.mult(viewMat);
mat.scale(s, s, s);
real2Screen = s;
mat.translate(x0, y0, 0);
transformed = false;
}
public void mouseDragged(MouseEvent e) {
int x = e.getX();
int y = e.getY();
tmpMatrix.unit();
tmpMatrix.xrot(360.0 * (mouseY - y) / getSize().height);
tmpMatrix.yrot(360.0 * (x - mouseX) / getSize().width);
viewMatrix.mult(tmpMatrix);
repaint();
mouseX = x;
mouseY = y;
e.consume();
}