Subtracting custom primitives from...

[system]

I am observing unexpected behavior when subtrating a custom primitive from my main piece of geometry. I wondering if I am doing something wrong.

First I have tool in Dynamesh mode, my main piece of geometry.
I switch tools by choosing a primitive like the star for example and head into shadow box.
Once in shadow box I clear the mask in order to create a new primitive.
I create the new pimitive and exit shadow box.
Next i want to use my new primtive as a new insert mesh brush, so I go to the brush palette and do just that.
Now that I my new insert mesh brush and it is based on my new primitive, I want to use in order to subtract from my main piece of geometry. To reproduce, just use a sphere and make it 128 dynamesh to experiment on.
I also want to use radial symmetry on the Z axis with 3 or more copies, so I set that up.
So, using the alt key, because I want to subtract, I draw over my dynamesh.
The sphere is completely masked with item embedded into the sphere which you hope will subtract from.
I then clear mask (ctrl + drag) and then I then refresh the dynamesh (ctrl + drag) with the expectation that my custom insert mesh brush will subtract from the sphere.
To my dismay this does not happen! Instead it replaces my sphere with radially drawn shapes of my new insert brush and although it looks cool, it is so completely not what I expected and desire.

[system]

I just wanted to add some more explanation on re-creating the application behavior I am observing

The goal here is to take one piece of geometry and subtract its shape from another piece of geometry. In other words it cuts out the shape from the main piece of geometry using another.

The unexpected behavior only occurs when using radial symmetry with a custom insert mesh brush, which can be created using shadow box and then created to a brush. If I do not use symmetry then my custom insert mesh brush does in fact subtract its shape from the another piece of geometry. What is inconsistent about this is, if I use insert mesh brush which comes with zBrush like the Insert Cylinder for example and I use radial symmetry with it to subtract from my main piece of geometry then it works fine, custom insert mesh brush using radial symmetry does not. Instead the result is that main piece of geometry disappears or is replaced with the subtractive geometry.

To recreate follow these steps please.

Start with a dynamesh sphere at about 128. This will be the geometry you will cut out of.
Switch to a new tool or primitive like the star.
Bring up Shadow Box and use 128. The star should appear in shadow box.
Clear the mask in shadow box and create a box shape geometry within shadow box.
Use clipping brushes while still in shadow box to reshape the box into a non box shape.
Once you have your non box shape, toggle shadow box off and this will bring your new primitive or tool into canvas.
Go to the brush palette and create a new insert mesh brush and make sure you select NEW.
Once done you will see your new primitive now as a brush and it is pre selected for you.
Switch back to the dynamesh sphere
Turn on Symmetry, select the Z axis only and turn on radial with a quantity between 8 and 12.
On your Depth sub palette adjust the graph so that dot is below the line. This will enable the insert mesh to draw deeper into the sphere so as to cut out more its geometry.
Draw on the sphere, but do so holding down the alt key so that you do not add, but rather subtract.
Once done the sphere should be totally masked.
Clear the mask
Refresh the dynamesh to hopefully observe that the custom insert mesh should subtract from the sphere, however in my work it does not, but rather replaces it.

If anyone can experiment with this and please let me know your results, would appreciate it.

To see how this is supposed to work “correctly”, use an insert mesh brush that comes with zBrush and repeat the steps starting at the point, “Switch back to the dynamesh sphere” and following the remaining steps. Once you refresh the dynamesh you will see how the insert mesh brush subtracts from the sphere as expected.

Thanks

[zber2]

In ‘Tool > Geometry > DynaMesh’, you have to turn on ‘Groups’ (MultiGroups DynaMesh). This is only necessary for IM’s that were created in Shadowbox.

[system]

zber2 you are awesome!! Groups solved my problem.

So you see everyone… its not the software being goofy or buggy, its the user’s knowledge and his/her ability to know what the tool can do and how to use it.

Thanks zber2.

[zber2]

No problem!