# What is the Box2D coordinates system?

I know that for Box2d I need to translate pixels to meters which is easy peasy. However my problem is what is the orientation of Box2D coordinates system? Is this the same as screen one (right += x, bottom += y) or it is like cartesian (right +=x, bottom -= y) ?

Also, does Box2D coordination system use negative values?

Thank you.

• It should not matter so long as your are consistent. Just use the same one as the rendering technology you are using to avoid confusion. Commented Feb 14, 2013 at 19:18
• @ClassicThunder I think that for example it matters for gravitation. I mean when a body is dropping, box2d will decrease its Y and on the screen it would go up in that case, if it uses cartesian system. Commented Feb 14, 2013 at 19:21
• "I mean when a body is dropping, Box2D will decrease its Y" You can specify the direction of gravity and so long as you are consistent it works. I use a gravity value of (0, 98.1) for my game because the top left is 0,0 and higher values of y are towards the bottom of the screen. Commented Feb 14, 2013 at 19:32
• @ClassicThunder So that's a good news, I can use screen coordinates in Box2D. If you want create an answer describing it and I will accept it. Commented Feb 14, 2013 at 19:34