ZBrushCentral

Mimicking Boolean Operations

ZBrush Usage Questions
#1

Hi all,

I have read (on these forums and elsewhere) that zCut is the closest you can get to performing boolean operations.

I have been trying to create a hollow pipe by drawing two cylinders on the canvas with different heights and radii, and then getting the longer thinner one to cut into the other one - thus creating a hollow pipe.

I’m not having much success so far …

Now my goal to create a hollow pipe is secondary, but my primary aim is to see how far I can go with pseudo-boolean operations, to see what I can and can’t do and learn something in the process.

So, how can I …

(1) Draw two cylinders on the canvas with different dimensions (radii and lengths), and align them exactly along their axes ?
(2) Save the result as a zBrush tool ?

Any tips appreciated, and I hope this all makes sense.

regards,
Andrew

#2

I would do it outside of ZB to be honest as booleans are notoriously horrible to create, Silo would be your best bet as it’s cheap, easy to use, stable & has a full demo for 15 days or so…

Just create your tube & save as a OBJ then import in to ZB…

Silo

#3

Try masking the entire thing, going to sub tools and clicking ‘extract’. There is a slider there that lets you control the thickness, so you’ll end up with a hollow tube.

#4

Thanks guys. I think you are missing the point though.

The bottom line is that I want to see how you can use zCut, and then be able to “pick up” the result and save it as a zTool. The problem for me is - once you have started using zCut with the second primitve (in this case, the long narrow cylinder) - that the original primitive (in this case the original cylinder) has been “flattened” on to the canvas.

Also when using zCut, is it possible to move the second cylinder to be co-axial with the first cylinder. I’m not talking about doing it by hand, I’m talking about machine-tool precision. Perhaps using markers ??? … I can’t work it out.

I think I’m struggling a bit in making myself clear. There’s something similar to what my goal is here, although they use a different technique to what I projected :

http://www.zbrushcentral.com/zbc/showthread.php?t=9776.

I don’t seem to get anywhere near the same results though. For example, when I “hide points”, I just get jagged edges, even after rendering … and I can’t find the “Clear” command.

#5

Now I only know about ZB2 - but zcut with regard boolean cutting is only something you can use when cutting pixols into pixols on the canvas.

The clear you mention is, "clear the canvas " cntrl+n ; although this step is not necessary.

Your jagged edges might be because you trying to remove quads that are describing an irregular form rather than boolean cuts in their truer sense, that cut across poly boundaries. Zbrush doesn't like ngons and is not overly fond of tri polys that remain fron such operations but either way it does not supply this method as you are aware. You might be better in certain circumstances to polymesh say your cylinder tool at an h and v divide setting for the polygon count that suites your needs > and then use the polygon selection modes whilst the mesh is in in edit mode to hide the polys you don''t require> Geometry > delete hidden polys> Morph Target>store a morph target >Tools Deformation> inflate your mesh > morph > create difference mesh > a new mesh is created that now has the hole and the inner polys. i.e thickness If you wanted to create holes across the shape you would have to employ the subdivisional modelling technique within ZBrush of first of deleting hidden geometry of your polymesh tool in edit mode > moving the points that described the edges of the deleted polys to describe a basic subdivisional circular form > use the difference mesh method described and then up the mesh's subdivision to make the subdivisional circular form a smooth hole/circle.

Getting familair with the basic tool’s initialize sttings will also help e.g the cylinder tool has an inner radius option for a centre hole.

The picker has options to place your tools on the canvas at angles,you have rotate options in tools >deformation and you can also use the rotational controls with shift held down when your in transform mode to rotate your tool to 90 degress implements regardless of the effect of the normals of the pixols your object is over.

Here’s a further link that may clarify things for you http://www.zbrushcentral.com/zbc/showthread.php?t=37585&highlight=zcut

#6

Thanks for your reply, boozie-floozie.

I’ve got to say I’m still quite confused by it all. I have ZB3 (and still have ZB2 installed), by the way. I think I’m slowly coming to the conclusion that zCut is NOT the way to go for what I want.

Re what you said “You might be better in certain circumstances to polymesh say your cylinder tool at an h and v divide setting for the polygon count that suites your needs” - I found that once I made it a polymesh3D, I was no longer able to edit it, so I remain confused on that point.

AAAAhhhhh … Hopefully, I’ll understand it all one day, but sometimes I wonder if I am not wired to easily understand zBrush ((:small_orange_diamond:

#7

When you make a polymesh of the tool it will create a new tool that will appear in the tool list rather than making the current tool you have in edit mode a polymesh.You’ll need to draw the new tool on the canvas and switch into edit mode to begin editing it. Hope that helps.

by the way. I think I’m slowly coming to the conclusion that zCut is NOT the way to go for what I want.
:slight_smile:

Don’t worry the penny will drop with ZBrush - give yourself a relaxed deadline to learn about all the features. But I think the concept of “Tools” trips up a lot of people when starting.

#8

I’m still struggling to get the desired effect, as they obtain in :

http://www.zbrushcentral.com/zbc/showthread.php?t=9776

The attached image shows some of the problems I am still having. Am I getting any closer ?

Attachments

ZBrush1.jpg

#9

ok by the colour I’m guessing your in v3.
In v2 if your tool is a polymesh you will have the option of deleting hidden geometry but not if it is a standard tool where/when you can only hide points as in the example your showing - this is fine if you want to follow the method in that thread rather than the method I outlined or the link I gave you.

If you wish to use the method in the link you posted just make sure you follow the recipe given and hide dem points.

#10

You can cut tools out of tools using projection master (using the ALT key with the other tool selected)

I know this might not be what you’re looking for, since it’s not a perfect cut out but rather a displacement – also it doesn’t cut through the mesh. Still related as a concept so posting anyway :o

Attachments

demo.jpg

#11

boozie floozie -

yes, ZB3.

the picture shows a sphere where (using masking) I have hidden an equal number of end-points at either pole. My question was, why does the “delete hidden points” not appear in the Geometry sub-menu, after I have done this ?

Also, why does it have a hollow appearance, like an egg-shell, instead of having true 3D substance ?

rrray -

thanks, not what I am looking for, but I have nevertheless learnt something new from your example, which is great !!

#12

No such thing in Zbrush. And there are no Booleans either. There are canvas based functions which can subtract height information from vertices in the axis of the orthographic view. That’s it. If the ‘optical’ illusion is ok… then you are in luck, if not, then you just encountered the limitations of the ZBrush faux Boolean. Look on the net for MOI (Moment of Inspiration). A tool in work by the original author of Rhino3D. THAT has booleans like the one you like to see, and yes, you can get those into ZBrush. And it’s free as long as it’s a beta.

Cheers
Lemo

#13

Thanks, lemonnado. I take your point. However, I still want to be able to achieve what the linked tutorial achieves, which I’ve not been able to do.

The image that I attached states what problems I’m still having.

BTW, I followed the links in your signatures, your zScripts look great. Can you tell me if they have incorporated any of this functionality in ZB3 ?

#14

yes, ZB3.

1,the picture shows a sphere where (using masking) I have hidden an equal number of end-points at either pole. My question was, why does the “delete hidden points” not appear in the Geometry sub-menu, after I have done this ?

2,Also, why does it have a hollow appearance, like an egg-shell, instead of having true 3D substance ?

1, I’m presuming there’s no delete hidden option because the tool is not a polymesh. Select your sphere and then press the make polymesh button and then attempt your operations.

2,That’s correct and thickness is created by 2 opposing and connected groups of polygons using the difference mesh technique discussed earlier.
If you can see both sides of a mesh without “thickness” it means double sided is switched on which just applies a visible normal to the polys facing away from you.

#15

Hey guys success at last !!!
Thanks for your assistance and patience (esp. boozie floozie), to see me through to a good conclusion :slight_smile:

#16

Pleased to hear that.:slight_smile:

#17

I was just wondering the exact process on how to do this method. Can anyone explain it a little better.

I have a half head that I want to take a smaller head and in a scense hollow it out following the contours using this method.