Pixologic discovers physics

Aug 28, 2020 at 10:03 am by Warlord720

Pixologic discovers physics: Dynamic cloth and brushes

Keeping in form Pixologic has finally added what most of us would call physics with its 2021 version. Of course, Pixologic is not most of us and ZBrush is such a different animal compared to other 3D tools that calling it Dynamics is not a surprise. It's more like what we are used to seeing with things like softcloth in other applications. Minus the mess. 

This early version is easy... not simple... just easy. Much easier than when other 3D tools implemented their physics. It's not like ZBrush is starting off with a crude initial setup. This is a lot more polished and I have to say that early tests with the Liquify option are very promising… and …fun.

The 2021 release comes with a lot of new cloth brushes to manipulate your softcloth mesh. There is also MicroPoly that improves the look of the cloth mesh but has a few hoops to jump through to create your own such as (from the ZBrush What's New documentation):

  • The mesh must be very low-resolution. This is because ZBrush will be repeating it many times and the total number of polygons being handled will quickly become quite large.
  • The mesh must fit perfectly into the ZBrush unit square. (The Tool >> Preview window is exactly one ZBrush unit across.) This ensures that the mesh will tile correctly.
  • The edge points must match up. This allows ZBrush to weld the points

 

Dynamic properties like thickness work on the fly with the cloth adapting to the thickness setting along with slider controlled self-collision that can be turned on and off. For collision objects, you use visible sub-tools or turn off any sub tools you want to be ignored by the simulation. As you can see it pretty much has what we need to add more realistic cloth in ZBrush without having to be super skilled at cloth wrinkles and all that goes with that.

The simulation can provide a starting point for more realistic cloth including draping or can provide the end result with proper setup for the draping. It is a very simple process to learn the basics but like all physics, you have to figure out your own workflow to achieve desired results. This means lots of experimentation in the early stages.

Draped Cloth ZBrush 2020Before and After Dynamic Cloth Draping

My testing… armed with little to no information as usual… was painless and actually fun to learn. For my first custom project, I chose an AC Cobra car model which I then imported into ZBrush 2020 via FBX import in the ZPlugin menu. It came in as a complex model with a lot of sub tools that I promptly merged down to one tool again using choices from the ZPlugin menu, specially Merge in SubTool Master.

I put in a 3D Plane and rotated 90 degrees then positioned it above the car model as you would with most cloth physics tools. After this, it was a matter of hit-and-miss changes in just about everything on the Dynamic menu which I moved to the left open panel that a lot of users keep closed. Docking the Dynamics menu is almost a must so you can get instant access for tweaking.

Finally, I got the result I was looking for in a thick, cloth cover for the Cobra. Just about any softcloth simulation can do thin cloths but I found ZBrush's ability to deal with thick cloth dynamically to be pretty robust for entry-level physics. I mean Dynamics. Whatever your cup of tea it works and overall, my experience was very positive even though my attitude wasn't, but it didn't take long to turn that frown into a smile with the results.

This is just one of the new features and I'll be back in a future installment to go over the other new toys Pixologic has given us with the release of ZBrush 2021.


M.D. McCallum, aka WarLord, is an international award-winning commercial graphics artist, 3D animator, published author, project director, and webmaster with a freelance career that spans over 20 years.  Now retired, M.D. is currently working part-time on writing and select character development projects. You can learn more about MD on his website.  






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