PDA

View Full Version : Autotet Example



dmmjedi
09-03-2009, 12:42 AM
One of the key elements of creating DMM objects is the creation of the "cage" around the object. This can be a difficult process depending on the complexity of the object. We now have a tool to accelerate that process quite a bit. This tool has been in development for some time and is now being integrated into the next revision of the plug-in (along with a better, friendlier licensing system). The example I am attaching to this topic is created with the Paint Effects tool. It is the "Down Brush", basically a palm leaf. I took the paint effects object and used the Modify menu to turn it into a poly mesh. The leaves and stem were turned into seperate objects which made the next step easy. I first used Autotet to build a cage around the leaves mesh and then around the stem mesh. The cages were then used as triangulated inputs to the "create DMM object" action and then the surface meshes were added. I did use the fill holes option in the polygon menu to close up the holes in the paint effect meshes. The DMM objects were then implicitly glued by superimposing them (essentially leaving them where they were relative to each other). Then I adjusted the stem to be stiff and the leaves floppy and dropped a cube on the stem. You can see some of the nuances of movement resulting from this. I am sure more can be done, but I wanted to share this with everyone as we got it working.

Cheers,
Dmmjedi

Breaker
12-01-2009, 03:02 PM
Sounds really interesting. I frequently find the ideal is to use as coarse a cage mesh as possible, ideally a primitive with scale transforms intact (this is important) as it gives the best possible control of the tets. Consequently I have a few rudimentary scripts that create primitives based on the full resolution assets bounding box, then shrink wrap these primitives back onto the mesh (you control how much resolution is in the primitive prior to the shrink wrap). This would be great to have integrated into the plug-in and is relatively straight forward using closest point.

Are you working from primitives or are you creating a proxy offset surface that you can control the mesh resolution of? It would be great to have both as the latter would be very handy for difficult shaped meshes although I'm guessing will yield higher tet counts, hence the need of an additional coarser method.

dmmjedi
12-01-2009, 07:46 PM
The Autotet tool works from the original surface mesh. The mesh it creates can be used as a seperate entity or you can automatically invoke it to create and associate a DMM mesh with a visual mesh. The surface mesh doesn't need to be watertight, which eliminates a lot of difficulty in authoring DMM objects.

You have control of the distance between the surface mesh and the Tetcage as well as the relative density of the mesh. I find that using Autotet (or Autocage as we call it) gets you much lower density meshes than you could create by hand for fairly complicated objects. We have been improving it on a continuous basis and have had a lot of VFX experts bashing on it before its release, so I can say confidently that it is a fairly solid piece of code.

Try it out and let us know what you think!
Cheers,
dmmjedi

Breaker
12-01-2009, 08:17 PM
Excellent!

If you don't require a watertight mesh then are you still able to define objects as breakable? If so then as you say it would save a lot of effort regarding authoring of models.

Is it available in your current latest build or beta? If so I'll make sure we upgrade to this.

dmmjedi
12-02-2009, 02:21 AM
The tool is available in the latest release. You can get it from the support area or from the main download link.

The latest build also has a new contact model and direct solver. The combination of these things allow much more accurate collision while improving the quality of the simulation. The simulations can run slower though, due to the direct solver's different methods.

Enjoy!

dmmjedi
12-03-2009, 01:57 AM
It seems I had some inaccuracies in my last post. The new contact model and solver are not in this build, though the autotet/autocage stuff is. We will have a beta build next week that will have the new solver and new contact mode in it.

Sorry for the confusion.