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dyn4j Project Setup Video

I finally got some time to create my first How-To video for the dyn4j project.  The first video describes how to setup a Java project in Eclipse to use dyn4j.  It’s short and hopefully to the point.

Posted on December 29, 2011

Version 3.0.2

3.0.2 introduces significant changes in the Sandbox application along with some minor bug fixes to dyn4j and some new features. Specifically, small CCD improvements, a new fixture filter TypeFilter, and tangent speed settings on contacts. Bug fixes include: a fix to the Body.setMass(Mass.Type) method, auto-sleeping bug, and a rotation disc computation bug. In addition, both dyn4j and Sandbox have been internationalized (any volunteers for translating?).

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Posted on December 20, 2011

Contact Points Using Clipping

Many have asked “How do I get the contact points from GJK?” or similar on the SAT, GJK, and EPA posts. I’ve finally got around to creating a post on this topic. Contact point generation is a vital piece of many applications and is usually the next step after collision detection. Generating good contact points is crucial to predictable and life-like iteractions between bodies. In this post I plan to cover a clipping method that is used in Box2d and dyn4j. This is not the only method available and I plan to comment about the other methods near the end of the post.

Posted on November 17, 2011

Version 3.0.1

3.0.1 incorporates many small changes. JUnit test, the TestBed and a new testing/demo application, Sandbox, have been moved around to better structure the project. Many major and minor bug fixes have been made. The most visible change is the normalization of the Joint class methods. In addition, the WeldJoint class now supports a soft joint setting.

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Posted on October 03, 2011

Version 3.0.0

3.0.0 incorporates big changes to the library. The base package has been changed, the broadphase collision detection code has been updated adding 3 new implementations, many bug fixes and performance enhancements, a new joint, better documentation, many more JUnit tests, new example applications, and more.

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Posted on June 05, 2011

How A Differential Gear Works

Had a friend of mine send me a link to this video on YouTube from the 1930’s explaining how a differential works. This video does a great job of explaining the concept and possibly the thought process that was used to develop it.

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Posted on March 29, 2011

Prismatic Constraint

The next equality constraint we will derive is the prismatic constraint. A prismatic constraint is like the line constraint except it does not allow rotation about the anchor point. A prismatic constraint constraints the linear motion of the bodies along a line. An example of a prismatic joint is the slide of a semi-automatic pistol. The slide is moved back to charge the weapon, then released to its original position. The slide cannot rotate about the pistol, nor can it move up/down or left/right only along one axis.

Posted on March 12, 2011

The dyn4j TestBed Now Uses JOGL

I recently released a new version of the TestBed application (which is used to test the dyn4j project. In this new version I decided to move from Java2D to OpenGL.

Posted on February 05, 2011

Version 2.2.3

The new version, 2.2.3, features updated Javadocs, 3 different CCD modes, and a new JOGL based TestBed.

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Posted on January 29, 2011

Version 2.2.2

The new version, 2.2.2, features one more joint, AngleJoint and a few minor bug fixes. The RopeJoint has been extended to allow for a minimum distance in addition to the maximum distance. See the javadocs or source updates for more details.

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Posted on January 15, 2011