Hey, I'm making my first proper 2D physics engine (I guess a kind of right of passage).

I've started by doing vector to vector constraints.
It works at the moment but it uses a kind of Master/Slave thing where one vector can move and move the other but when the slave vector moves it doesn't move the master (like a pendulum).
Here's the code:

//Finds out the angle between the vectors
angle = 90 + a.getAngle(b);

//Positions accordingly
b.x = a.x + distance*Math.sin(Math.toRadians(-angle));
b.y = a.y + distance*Math.cos(Math.toRadians(-angle));

Anyway of making it so they move each other?

Hi there,

Sure, you need to design your constraint so it works in 'relative space' and pushes on object A while pulling on B.

I wrote just the article which should help you out with understanding how to design a constraint:

http://www.wildbunny.co.uk/blog/2011/04/06/physics-engines-for-dummies/

It starts off dealing with simple concepts and builds up to designing a constraint

Hope that helps!

Cheers, Paul.

Thanks! took so long to get an answer. +1rep:)