# ODE in 2D

Hi,

I’m trying to create a kind of 2D box in which images fall on top of each other with collision detection. Like Tetris but with pictures and gravity. Being 2D I want the images to always appear flat, parallel to the screen.

For the collision detection I’m using ODE boxes. But being 3D boxes, when they collide, they rotate in all 3 axis. And this will not do because I need the pictures to be flat. I tried to ignore X and Y rotations and just use Z but, since ODE is actually using the three then the result is quite awkward and not realistic at all.

Another idea was to add a front and a back wall besides the floor, left and right walls. These extra invisible walls which would restrict the objects. Didn’t work. If I use spheres this works fine since they are round, But when I switch to boxes they get stuck in between the walls.

So, what I want is really simple. I want ODE to work in 2D instead of 3D. This way the (2D) boxes would always be perpendicular to the screen and everything would work fine.

How can this be accomplished?

(ODE is amazing by the way!!!)

Thanks!,
Nuno

Hi,
our mate diki made a nice patch simulating ODE in 2d…take a look at flumni

Hi Desaxismundi, apparently that patch only detects collisions with the borders, but not with other moving objects.

Thanks anyway!

Another way to make ODE behave well in 2D would be to remove friction between the box and the plans. I’m not sure this would work, though.

Can friction be removed in ODE?

this example (pong project) you can be you profit.

I am also in the process off making my own ODE like stuff.
A new way off thinking using Polar/Cartesian for the ball, every ‘hit point’ forms the ‘new’ centre off the Cartesian node.

I wanted to make a 3 player pong for my multi-touch, still having hard time with the angle in = angle out stuff (ANY IDEAS??)

Any way, I have a formula that detects the hits with lines, if you have moving lines it works the same.

I will attach my proof off concept for the hit detection. Fiddle with the diameter stuff and forget the GDI stuff.

balHitTEST.v4p (46.5 kB)

Thank you so much for all your help!

Actually, I ended up solving the problem in the happiest possible way. I took advantage of it. Instead of trying to make the system become 2D I found a nice way to make my result become 3D.

Reducing the cube depth until I got a very thin 3D “square” which now simulates materialized photographies. Well, it’s hard to explain.

Anyway, I’m happy!!

Thanks!

Regards,
Nuno