View Full Version : cleaning up after shattering

06-16-2017, 05:39 AM
Hi According to the manual bullet doesnt like 1 and 2 point polys. After shattering the mesh cleaning up the singles doesnt seem to do any damage but after selecting the 2 point polys and deleting them big holes appear in the models - is there any best practice to follow or is it all just trial and error



06-17-2017, 04:35 AM
Are these results due to 1 and 2 point polys or something else?


06-17-2017, 10:07 AM
I'm guessing you did a Merge Points after the Fracture, which I think might explain holes appearing when deleting 2-point polys and the sharing of fixed points with exploded geometry in the sample animation.

RE: deleting 2-point polys, it *shouldn't* produce holes in the mesh, but you might have luck doing a three-step process: 1) select 2-point polys, 2) press "k" to kill them but leave the points, and 3) delete points which belong to zero polygons.

Good luck!

06-19-2017, 07:01 AM
Thanks yes I think I did merge polys - not sure how I'm going to undo that one!
thanks for the tip on kill polys though - I hazy on the use of anything with less than a triangle, time for some research.

06-19-2017, 07:25 AM
Hopefully, you kept the original pre-Fracture model and can do the Fracture again and avoid the Merge Points. Otherwise, I don't know how you'd identify "incorrectly" merged geometry and points except VERY slowly and instance by instance.

I'm not a Fracture / Bullet expert, but when I use Fracture I specify a very small offset for the pieces (e.g. 2mm) and keep the original. Then in the animation, I do the Bullet simulation until my Collision object breaks up the Fractured object and set up a single-frame (or maybe 2-frame) Dissolve from the intact original object to the Fractured object on the frame(s) where the collision occurs. That way, the original object appears pristine until the collision, and the edges of the fractured object don't appear before it's broken apart.

You shouldn't have to use the 3-step Kill method I suggested. Deleting 1-point and 2-point polygons shouldn't effect any tri- or quad- geometry visibility.

Again, good luck!

06-19-2017, 04:32 PM
You should do Merge Points first, then Unify Polys, then you can delete 1-2 point polygons.
If hole appears in model, it might mean that it has flipped polygons.
You can check that by toggling on/off double side in Surface Editor.
Select flipped polygon, and press f, to flip it again.

Triangle can have sometimes one common position vertex, and looking like edge/line. After Merge Points they're unified. And from triangle there is made 2 point polygon.

06-20-2017, 06:16 AM
I've never rated the Lightwave fracture tool, so you might get a cleaner fracture importing the object into the Blender Fracture Modifier.

06-20-2017, 08:38 AM
i ran some tests on cleaning up fractured objects, might be of help...


06-21-2017, 12:17 AM
thanks that terrific