how can you translate 3d objects coordinates to screen coordinates?

[bak 2]

Is it possible to get the X,Y coordinates of a gameObject or NPC on the screen?

[jarred788 9]

ya you should be able to easily. 

Not sure what these return but they sound like what you are looking for.

yourObject.getLocalY()

yourObject.getLocalX()

yourObject.getGridX()

yourObject.getGridY()

 

https://dreambot.org/javadocs/

look at api under gameobjects.

 

[Xephy 237]

Both of the things you've listed fall under the Entity parent class. You can call Entity#getTile#getX or getY accordingly to be given the proper X and Y coordinate.