Simple and Efficient Approximate Convex Decomposition

RBD · **Joined:** Tue Sep 16, 2008 11:31 am **Posts:** 118

Has anyone tried to implement K. Mamou's "A Simple and Efficient Approach for 3D Mesh Approximate Convex Decomposition"?
Described in Game Programming Gems 8 - Chapter 2.8, p.202
First published in ICIP 2009 proceedings: A Simple and Efficient Approach for 3D Mesh Approximate Convex Decomposition (PDF)

Thoughts?

Erwin Coumans · **Posted:** Sat Apr 09, 2011 4:48 am

That looks interesting. I contacted the author and asked for his source code.

There is a good chance that we can add it to a future Bullet SDK, as improved convex decomposition is valuable.
Thanks for the link!
Erwin

khaled · **Joined:** Mon May 02, 2011 3:26 pm **Posts:** 14

RBD · **Joined:** Tue Sep 16, 2008 11:31 am **Posts:** 118

Hi khaled, that is wonderful, thanks for sharing this as open source. I trust it will come in very handy for physics simulations. I personally would also be interested in trying some things with HACD and Blender; I look forward to playing with / testing your HACD project resources in the near future (unfortunately, I cannot at this time; but I do want to acknowledge and thank you for it).

ngbinh · **Posted:** Thu May 12, 2011 11:49 pm

Looks great!

Thanks for the work!

jratcliff63367 · **Joined:** Fri May 20, 2011 8:22 pm **Posts:** 1

I just wanted to confirm that I have had time to review the work of Khaled and it is amazing. He has done an incredible job; especially in providing this code open source to the development community.

I made an announcement on my blog that the old approximate convex decomposition work that I did is now considered completely deprecated and I will no longer be using it myself any more.

http://codesuppository.blogspot.com/201 ... onvex.html

dphil · **Joined:** Tue Jun 29, 2010 10:27 pm **Posts:** 237

This is great! With the help of some code posted by Flix (viewtopic.php?f=9&t=7063), I have incorporated HACD with bullet in my simulations. I like how nicely it handles an object like this:

Original (3600 triangles), decomposed (134 clusters), and Bullet debug line drawing of the associated btHACDCompoundShape, respectively.

khaled · **Joined:** Mon May 02, 2011 3:26 pm **Posts:** 14

Dear all,
A new HACD version is available http://sourceforge.net/projects/hacd/
Have a look at my blog for the details http://kmamou.blogspot.com/

--Khaled

dphil · **Joined:** Tue Jun 29, 2010 10:27 pm **Posts:** 237

Great stuff, thanks Khaled! Looking forward to trying out the improvements.

RBD · **Joined:** Tue Sep 16, 2008 11:31 am **Posts:** 118

khaled, I've finally been playing around with HACD and it's working really well; it's quite impressive. Also the new decimation feature is really handy (even works with non-manifold meshes, great) and your recent blog post on the HACD parameters has been very useful as well.
Thanks, much appreciated!
(BTW I posted one of my first HACD tests with Blender & Bullet Physics as a p.s. to a recent (voronoi) video to spread the word on your great tool: real-time, rendered.)

khaled · **Joined:** Mon May 02, 2011 3:26 pm **Posts:** 14

Thanks. Great demos by the way...
--Khaled

Karrok · **Joined:** Fri May 13, 2011 1:11 pm **Posts:** 62

How can I decouple this from wavefront?

Starting with a simple btBvhTriangleMeshShape for example.

How can I use convex decomposition on this shape?
Currently the demo only shows the case where a wavefront object is loaded with a lot of data that is not present in the btBvhTriangleMeshShape.

RBD · **Joined:** Tue Sep 16, 2008 11:31 am **Posts:** 118

Karrok wrote:

How can I decouple this from wavefront?

The HACD class is not coupled to any format. You simply point it to your vertices and triangles using SetPoints()/SetNPoints() and SetTriangles()/SetNTriangles(), then (set params and) call the Compute() method...

Karrok · **Joined:** Fri May 13, 2011 1:11 pm **Posts:** 62

Then the question becomes, where is the above information available from a btCollisionShape, btTriangleMeshShape or btBvhTriangleMeshShape

Flix · **Joined:** Tue Dec 25, 2007 1:06 pm **Posts:** 318

Karrok wrote:

Then the question becomes, where is the above information available from a btCollisionShape, btTriangleMeshShape or btBvhTriangleMeshShape

In the btStridingMeshInterface. I've posted the source code here: http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=17&t=7159.

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Simple and Efficient Approximate Convex Decomposition

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