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javafxjavafx-8

How to get the absolute rotation of a Node in JavaFX

In JavaFX the rotateProperty of a Node provides me with its rotation in degree relative to its parent. Is there a way to get the absolute rotation in degree, either relative to the Scene or the Screen?

For example, is there a way to calculate the angle from the Transform object of a Node i can get from getLocalToSceneTransform()?

Solution

  • So, i did the math myself, and for my case i either get the rotation in Radians via:

    double xx = myNode.getLocalToSceneTransform().getMxx();
double xy = myNode.getLocalToSceneTransform().getMxy();
double angle = Math.atan2(-xy, xx);

    or 

    double yx = myNode.getLocalToSceneTransform().getMyx();
double yy = myNode.getLocalToSceneTransform().getMyy();
double angle = Math.atan2(yx, yy);

    In both cases this can be converted to 360-degrees:

    angle = Math.toDegrees(angle);
angle = angle < 0 ? angle + 360 : angle;