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View Full Version : Fracture tools need some work...



m.d.
11-25-2013, 11:17 AM
Not bashing LW here....but just to keep the developers aware...the fracture tool really needs work.

I was fracturing a rather complex object...couple thousand poly's but basic shape. Poly's were laid out in a grid like flow.

Using LW fracture inside modeller, voroni algorithm leaves many holes in poly's and thin poly's and a lot of stray points.....I would bet 50% of the pieces needed major work(filling in holes....non planar polygons folded over each other ect)
The other algorithms were slightly better....maybe 20% were not perfect and needed some work.....the chunks were not as visually pleasing as through voroni of course.

After spending an afternoon trying....I sent the model into realflow and fractured it using there voroni tool.

1 click.....no errors....no stray points no non planar poly's.

It's the same every time with every object. Fracture is simple and clean.

Not sure what realflow is doing different....but right now on anything but the simplest fractures....I am taking the hassle of exporting to realflow (RF won't export fractured as Obj...so requires making a blank sim...exporting realflow SD...using MGsavetransfromed....and collapsing all object inside modeller)

Despite all that work, it is far easier to deal with realflows fracture tool.

And I am aware of the various techniques to get a better result with LW fracture....they don't always work with all geometry...especially high poly.

RF works every time first click....no tricks needed.
Hopefully this can change inside LW

hrgiger
11-25-2013, 12:57 PM
not having used it, would say shattering a piece of glass in RF for a bullet sim able to be rendered without seeing all the fracture lines due to the refraction of all the glass pieces (i mean before the glass is shattered)? i just always assumed that the best solution might be to use object replacement at the frame that the impact happens, replacing a unbroken piece of glass for the fractured one. That way it woudnt matter if the LW fractured glass had holes or other imperfections you wouldnt really notice it. And replace i mean make the unfractured glass transparent at impact and make the fractured one visible.

bobakabob
11-25-2013, 01:02 PM
Did you triple the ploys in Modeler before using Fracture? I haven't used Fracture much but recently it worked fine on a really complex model.

m.d.
11-25-2013, 09:14 PM
Did you triple the ploys in Modeler before using Fracture? I haven't used Fracture much but recently it worked fine on a really complex model.

just tried again with tripling....46 stray points 40-50 holes and spikes

m.d.
11-25-2013, 09:19 PM
not having used it, would say shattering a piece of glass in RF for a bullet sim able to be rendered without seeing all the fracture lines due to the refraction of all the glass pieces (i mean before the glass is shattered)? i just always assumed that the best solution might be to use object replacement at the frame that the impact happens, replacing a unbroken piece of glass for the fractured one. That way it woudnt matter if the LW fractured glass had holes or other imperfections you wouldnt really notice it. And replace i mean make the unfractured glass transparent at impact and make the fractured one visible.

that could all work...but with this thicker sculptured pieces and you would definitely notice the holes...even swapping them out at render(which I did anyway) you still seem them on the large chunks...
for a simple plane of glass ect...no problem...just delete the little polys floating and sim away

the main point I was saying is that RF seems to work flawlessly with any geometry....I never got 1 usable fracture on this geo within LW...I never got 1 bad one using RF

Lewis
11-26-2013, 01:07 AM
I feel your pain. I tried to Fracture complex meshes dozen of times in LWM and anything more complicated than simple boxes/spheres or low poly objects was a BIG problem, too many fixes, especially stray points going all over the place like spikes :(. I guess Ikeda has lot of work to make Boolean algorithm work much better before Fracture could come close to clean results :(.

Brötje
11-26-2013, 01:50 AM
I feel your pain! I usually resort to fracturing in Blender or the Houdini Apprentice edition ( you can export an OBJ ). I must say that Blender Cell Fracture ( now standard in the latest version ) does some nice things and is also capable of creating wood splinters. Furthermore I have found that Lightwave and Blender play very nicely together.

Do check:

http://cgcookie.com/blender/cgc-courses/breaking-objects-with-the-cell-fracture-add-on/

http://www.youtube.com/watch?v=w_m81zF9WtY

pinkmouse
11-26-2013, 04:27 AM
http://cgcookie.com/blender/cgc-courses/breaking-objects-with-the-cell-fracture-add-on/

Loving the voice recognition subtitles track! :D