Rotating About a Point

Troubleshooting General Help
1

Here is a question I’m having, is there a way to rotate an object, not around itself, but around an outside point.



example:



In the earth’s revolution around the sun, it spins on (about) the y axis. But it also spins around a given point also, so it physically moves, rather than spinning.

2

Attach it to a node, distance it from its parent(node) by moving it a bit, and rotate the parent.



https://wiki.jmonkeyengine.org/legacy/doku.php/jme3:scenegraph_for_dummies

3

sure is, have a good look over the Scene Graph for Dummies, should help clear up all your questions :slight_smile:

4

Thanks, when I started I skimmed through the scenegraph, because I’ve done little 3d software with lwjgl, but I now realize that it’s obviously a bit more advanced.

5

there was many Similar topics like

http://hub.jmonkeyengine.org/groups/general-2/forum/topic/camera-rotates-and-facing-an-object-by-key-input/

6

hey chessmaster,

how do u rotate a spatial abt its own axis?as far as i know, when i call rotate method on a spatial it gets rotated abt it parent node, and if u

call rotate on a node then all of its child nodes gets rotated abt it?

only way seems to me is to make a node positioned on object’s centre, attach object to this node and then rotate node.



Manish

7

the way I’m doing it is : “Geometry.rotate(x, y, z)” and that rotates it around itself.

8

sorry for late reply…if u have already got ur answer, then ignore whats ahead…



calling rotate on a spatial rotates the spatial abt its own geometrical axis…

so if ur objective is to rotate the spatial abt an outtside point(‘axis’ is the proper word), then make a node, place it on this point(axis) of interest and attach ur spatial to this node and then call rotate on the node rather than spatial…