Jump to content

  • Log In with Google      Sign In   
  • Create Account

Banner advertising on our site currently available from just $5!

1. Learn about the promo. 2. Sign up for GDNet+. 3. Set up your advert!

Irlan Robson

Member Since 08 May 2012
Online Last Active Today, 05:12 AM

Topics I've Started

Bounce v1.0 Release

24 July 2015 - 12:51 PM

Good afternoon everyone.

I'm happy to distribute Bounce, a lightweight and portable 3D physics engine for games. 

Bounc3 is available at GitHub. 


Some of the physics engine features can be seen at the basic (.pdf) documentation, living inside the repository. Additionaly, a demo application lives inside the repository as well.



Irlan R.

Adding restitution to the MLCP

24 May 2015 - 08:22 AM

The compl. cond. for the contact and impact in a vel. based formulation is:


Ju(t + dt) + eJu(t) >= 0 _|_ lambda >= 0.


where u = system velocity, and J is the normal jacobian, e is the coefficient of restitution.


My question is:


Using an error correction term b, the condition becomes:


Ju(t + dt) + eJu(t) + b >= 0 _|_ lambda >= 0




So, defining low = 0, high = infinite, passing thourgh all simplification, assuming acceleration = ( u(t + dt) - u(t) ) / dt, we have


A = J*M^-1*J^T,

x = dt*Lambda

b = J * ( u(t)+dt*M^-1*f) + eJ*u(t) + b, (f == external forces),


w = Ax - b _|_ low <= w <= high,



3D SAT Problem

10 April 2015 - 07:55 PM

Hello, newbie to SAT algorithm.
What am I missing in the SAT implementation below?


I think the problem is between the edge-edge case. Code doing all computations in world-space.

Graphs tool for a thesis (needing an suggestion)

13 March 2015 - 10:20 AM

I need a graphs tool to write my graduation project. I'm writing a rigid body simulation so I need to graph the Euler and RKs methods. I would like to know if there is one which I can do this fast. A free software if possible.

Friction Impulses (boxes are sliding on the ground)

09 February 2015 - 08:07 AM



The problem I'm facing with is with correct impulses but wrong behaviour. The physics engine uses split-impulses (bias-velocities), but when objects fall over a plane it starts to slide like if there was an joint above them. Here's a video:


[This video was deleted because was messing up with my channel, but it is what the description says]


The loop (at 60HZ = 0.016ms):


Update contact positions (contact caching not implemented yet, so skip it);

Check for collisions;

Apply forces (integrate velocities);

Prepare constraint data (normal inverse mass, two tangents inverse mass, and bias values);

Warm Start last frame impulses (contact caching not implemented yet, so skip it)

Apply Contact Constraint Impulses (10 iterations, zero accumulated bias impulse, etc.);

Apply velocities (integrate positions, zero bias velocities);


I'm skiping the warm start, but that doesn't mean that I should get the behaviour above.


Has anyone faced with that problem?


Here's the overview of each task: