ZBrushCentral

Mesh subtract not working

ZBrush Usage Questions
#1

Hi. I’m working with files for 3D-printing and have problems doing Boolean and “create shell” operations. Basically I will merge two subtools; the main subtools and the subtracting mesh. Then only make the subtracting mesh visible and from the menu;
Polygroups -> Group as Dynamesh sub

Now the main mesh is grouped (say in a red color) and the subtracting mesh is grouped as a sub-mesh, displayed in white.

Now, either I can choose "Geometry -> “Sub” or “Create shell”. Sub does nothing, and with create shell I get an error stating that I need a subtraction mesh for the operation to perform.

Is this a bug or am I doing something wrong? I believe this is exactly the workflow I’ve been doing before, though this is the first time trying it with Patch 2.

Hope you guys can help me with this issue.

Kind regards Tobias Jacobsen
Zbrush 4R6 P2

#2

You don’t have to do all that to create a shell.

To use a sphere and cylinder as an example and to make the sphere a shell.

  1. To make a subtractive mesh, just select the Difference icon on the subtool, in this case the cylinder (see first image).

  2. Select the sphere and go to ‘Tool > Geometry > DynaMesh’ and turn on ‘Dynamesh’ button.

  3. With the sphere still selected, go to ‘Subtool > Merge’ and click ‘Merge Down’.

  4. Go to ‘Tool > Geometry > DynaMesh’ and click ‘Create Shell’.

You can change the Dynamesh and Create Shell options to suit your needs.

new-2.JPG

new-3.JPG

#3

Thanks for the explanation. I know this is the quickest workflow. Just wanted to make sure I did the right thing, so kinda “spelled it out” to Zbrush.
Just tried following your recipe and it doesn’t work. Can you confirm that it works on your end with R6 P2?

#4

Works like a charm!

#5

Weird. I get inconsistent results. I have managed to get it working with simple shapes. When trying more advanced shapes it doesn’t work. After merged, the subtracting mesh is clearly white in wireframe mode, but when pressing “Sub” or just Ctrl+drag it just merges the shapes.

On the other hand, I can do the exact same thing with two simple spheres and it works perfectly.

#6

I think I might have found the issue. Try adding a shape and then instead of adding a new subtool to subtract, DUPLICATE the existing one. Then try to run the subtraction of the newly duplicated shape (after you moved it ofc)

#7

I might have a better solution for you. Instead of what you are trying, mask all but the bottom of your main tool. Goto the extract part at the bottom of the subtool panel and enter a small thickness value, enable double sided, then click extract. I may have included my ExtracT.txt file in the files I recently uploaded in a zip file. It will extract as per settings, then switch to that extraction(a new subtool) and clear the masking. You can certainly edit the macro to avoid clearing the mask if needed.

#8

If I append or duplicate, it still works the same. I end up with a proper shell.

#9

I just looked in the zip, no file. So, here it is.

#10

IN Zbrush 4R6 P2 ,both the “Group as dynamesh sub” or “subtools panel icon” is quite buggy.for example ,normally,The white polygroup is for subtract and will disappear after operation , but if you turn on dynamesh in different time, all the thing go wrong.maybe the white polygon still there but the main mesh disappear,maybe the main mesh become the subtract group and it cut the white one off…and maybe two mesh still there(nothing happen)…

#11

Yes, thats exactly my experience also. It would either just merge the subtools or invert the operation, so the main mesh became the subtract mesh. At one point it would leave the shared space only (the third bolean option)

Hope a fix is in the pipeline

#12

Did you try my script? Place in Macros:Misc; It should be easy enough to mask the bottom and then invert the mask. I highly recommend the Axis Plug for your workspace/flow enjoyment/usability.

#13

Any update on this? I get all sorts of crazy results trying to mesh subtract. Most often though the main object gets subtracted from the subtraction object.

4R6 P2 Mac

#14

What Mac OS? What method are you trying? Are you certain the tools are in the right order in the pallette?

#15

10.8.5

I’ve tried with the sub icon and with group as dynamesh sub. Neither works. I get the white polygroup for the sub object but I’ll get all kinds of crazy results for the boolean, none of them correct :frowning:

#16

I have not experienced problems since last time, so crossing my fingers that the process will continue to work for me.
Nevertheless I sincerely hope that the dynamesh Boolean-stuff will be a priority in the coming updates to Zbrush, so we can get a tool that works consistently.

Finding myself very dependent it, getting more and more jobs involved with 3D-printing.

#17

After some experimenting I’ve determined if the subtractive object is a dynamesh it doesn’t work. Turning off the dynamesh button for the subtractive object doesn’t help. A polymesh 3D that has never been dynameshed will subtract correctly.

#18

I think both would have to be the same type of base object, mesh or Dynamesh. Decimation or Zremeshing the unDynameshed object may make it work properly.

#19

Problem solved. In 4R6 you have to have Groups enabled on the dynamesh object that you are going to subtract from.

#20

Can you expand on that? What do you mean by “groups enabled”?