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# pizza123

Member Since 28 Dec 2012
Offline Last Active Jan 17 2013 02:54 PM

### How to find the net normal force acting on all object?

07 January 2013 - 07:37 PM

Hi,

So I'm making a physics engine and I'm having trouble calculating the net normal force of an object that is in touch with many other objects (it works for 2 but doesn't work for more). The scenario is a circle is between two other circles (ontop of them, in the middle) and there are more circles on top of that circle. There's also gravity acting on the circle. Right now the way im calculating the net force on the object is first I apply gravity to it, then I apply the normal force from the first object in contact and get a new net force, then I apply the normal force from the second object to the net force and get a new net force, and etc... However I'm not sure if what I'm doing is correct. Is this the way to do it or is it wrong?

Thank you

### How to find closest points between two moving circles?

06 January 2013 - 08:23 PM

Hi,

I'm trying to find the time of impact between two moving circles. Right now I was finding the closest distance between the circles (like if you just draw a line between their centres), however if the two circles are moving then the actual closest points (& distance) for impact are different. I was wondering what would be the easiest way to find those points?

Thank you

### Continuous collision detection

28 December 2012 - 07:36 PM

Hi,

I'm trying to make a 2D physics engine, and for the hit detection I'm currently using SAT. Currently all objects are stationary and the collision detection is discrete, but I'm trying to implement a continuous collision detection. I did some research and found out there's "swept SAT", but from what I understand it can only predict the collision between moving objects that are not rotating (but can't predict the collision between two moving rotating objects). However, I also found out about Minkowski collision detection and that it can work for continuous collision detection for moving rotating objects, but I didn't really do much research into it because I already have SAT. I was wondering if there's a way to predict whether and when two moving rotating objects will collide with SAT, or if I should try to implement the Minkowski collision detection (also, how hard is it compared to SAT?).

Thank you

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