[Odejava] picking objects and GeomRay

Game Mechanics
#1

Hi all,

I’m playing around with Odejava and it seems sweet! I would like to create a app where the user selects objects with the mouse and throws them around.
My approach is to construct a direction vector from the camera position heading to where the user clicked (converted to 3D-coords) and then send a GeomRay in that direction to see if I collided with something.

Is this a good way of doing it or should I think again? Anyone who has done this using Ode (or not using Ode) are more than welcome to post code snippets :slight_smile:

#2

Sounds like the typical approach. What graphics API are you using? I use Xith3D to generate a pick ray then test for interstections with the scene objects. I can then apply apply a force to the picked object proportional to the mouse drag length, object mass, local pick location, etc…

Edit:
Oh yeah, the force direction should probably be parallel to the view plane.

#3

Hi, thx for the reply.
I’m using AgentFX from http://www.agency9.se. I was sort of hoping to do this stand alone from the graphics API.

#4

Creating the pick ray can be tricky and requires some intimate knowledge of the graphics API. You need to take into account aspect ratio, field of view, projection policy, etc. I can’t think of any reason your approach won’t work provided you can create a correct pick ray and know the direction of the mouse drag.