View Full Version : Sub patch question

Ty Catt
09-27-2006, 09:21 AM
:grumpy: Hello all...

Is there a way to successfully Boolean Drill (subtractive) a sub-patched object?.

In a nut-shell, the object is just your basic rectangle with many subdivisions in order to obtain a nice beveled edge once sub-patched.

If I try to drill some holes and recesses for buttons (with Boolean subtract), I get weird mesh results.

If I "un-subpatch" the object first, then try to drill some holes, I get the "you need objects with 3 or four vertices in order to create a sub-patch" indicator.

Or should I scrap such a highly meshed sub-patch to begin with.

Is there a better way to get a nice rounded edged rectangle without subpatches?

Any suggestions?:help:



09-27-2006, 10:31 AM
You can try triple the polys on those problem areas.

09-27-2006, 10:52 AM
Subdivision takes a little planning, that's all. You'll want to avoid boolean, though.
I'll post some examples when I get home tonight.

Ty Catt
09-27-2006, 11:15 AM
I tried tripling...

Didn't help unfortunately...

Thanks for your suggestions.


09-27-2006, 11:39 AM
Rather than boolean subtract, divide your object to get the opposite faces of the hole and then use bridge to make it.

See below for example with boolean and this approach.

09-27-2006, 09:27 PM
Here's a model that I used Catmull-Clark on. I was able to reduce the poly count by 30%, roughly, by using C/C.
Current poly count is around 750. Nice round holes, not sharp at all.
I did use boolean to make the hole, but I patched it back together evenly, as you can see in the wires.

Ty Catt
09-28-2006, 06:52 AM

Thanks for you help!

I am not familiar with Catmull-Clark.

I am working with version 7.5. Is CC only on v9.0?

I do have version 8.0 on my TriCaster gear, if that would help.

I am interested in your solution!

Are you also suggesting I Boolean with an octagon and not a circle, does that help? Did you actually move and merge points back to "patch" the sub-patch together to form a nice round circle?

Will some of my screen shots help?

It is critical I get the nice rounded edges of the base object. The 10 discs in the background is my drill bit for the Boolean. Should I ditch the sub-patch method altogether?

Thanks again for all your help.


09-28-2006, 09:56 PM
Hey, Ty

Sorry it took me so long to reply, but I don't have LW at work.
Catmull Clark is something new with version 9, but you don't need it.
You definitely should continue to use subpatch method.
Here are some samples I made just now, in about 4 minutes.
It's just a square poly with a hexagon cut into it, then the hexagon was beveled. I made one with an octagon as well. The number of sides you want to use depends on your other geometry. You'll want to try to create only 4-point polys, but a few triangles here and there will be ok.
I'll try to post some more examples tomorrow if you want.

09-28-2006, 10:04 PM
One more quick sample...
Same hexagon geometry, multiplied and merged.

09-28-2006, 11:43 PM
It's just a square poly with a hexagon cut into it
I guess the question is: did you use boolean; and if yes, what did you do after to prep for SubD?

09-29-2006, 07:49 AM
I didn't use boolean, but I could have.
I used stencil to get the hex onto the square.
Then I killed the square poly, copied the corner points to the middle of the square edges, then connected points as I needed into polys.
After that, I beveled the hex poly several times, as you can see in the wireframe views.

Had I chosen to boolean, I'd have booleaned with a 6 sided disk.
I'd still have to kill polys and do the bevels, pretty much all the same thing.

As far as "prepping for SubDs" goes, look at the geometry. The beveling is what controls the softness of the curves, from the top down into the hole.
I used bevel to create more, closer spaced polys for that transition. The other thing is the geometry surrounding the hole I made. I broke it out into 4 point polys.
Where the pre-planning comes into play, and this really is the most important part, is looking at where your other holes are going to be and creating your hole geometry in a way that makes it easy to patch them all together evenly.
Maybe 6-sided holes will work, maybe 8 or 9 sided holes would work better.
(usually less is better, but 4 sided holes really don't deform well - I almost never go below 6)
The best thing to do is to draw the model on paper, and draw the poly flow too. You'll avoid all sorts of problems later with a little planning first.

Ty Catt
09-29-2006, 11:47 AM
Thanks, buddy.

You have helped me immensely.:thumbsup:

I will give your techniques a shot right away.

Taker easy,


09-30-2006, 03:38 AM

Thanks for that, most useful.

-I came up with this just as an exercise ( because I wasn't sure what you meant ) in a tenth of the time it usually takes me ... 8 doesn't seem to do a boolean on a square poly without adding unwanted and/or losing necessary geometry. So there's nothing to bevel.

-Never thought of using stencil or retaining the corner points.

Thanks again!



10-01-2006, 09:42 PM
I hope it gets you a little farther down the road, Ty.
Good luck with it, and have fun!

Nice work, Meshy.
There's so much I learned here, I'm glad to give back a little when I can.

Regarding the boolean function, I should have elborated more at the time. So I'll do that now with a few pictures.

#1 shows a grid, and (4) 8-sided disks that I want to cut out of it.
Notice that they're tapered just a little. Very important.
#2. Here, I've joined polys so that each disk cuts into a single poly. Also very important.
#3 shows what's left after the boolean.
#4 shows where I broke out the top surface poly back into quads.
#5. Here I've selected the bottom of each "hole" and moved it closer to the surface. This is why the taper was important. I now have the first bevel, and the bottom becomes the poly I'll use to bevel again.
#6 shows the result of 4 more bevels.
#7 shows the wireframe after the bevels, and after breaking the bottom poly into quads.
#8 shows the result of subdividing.

Boolean can be a great tool with a little planning. I try to only boolean into single polys when I can. Less clean-up that way.

10-02-2006, 01:25 AM

Gotcha! Again, your time and thoughtful effort is much appreciated.

:thumbsup: M

10-02-2006, 01:40 AM
Then I killed the square poly, copied the corner points to the middle of the square edges, then connected points as I needed into polys.

thats how i used to do it, but after proton explained about the connect tool it is a waste of time.

leave the square poly with its +4 polys...and then mark 2 points in it that you would like to use to split the poly by....and then just press connect.

faster becouse:

1: dont need to kill the +4 sided polys.
2: need only to select 2 points, instead of 4.
3: less chance for confusion with detailed modells (what point belongs to what??...)

find out more at: http://www.spinquad.com/forums/showthread.php?t=13545

10-04-2006, 04:39 AM
Poke holes using Boolean Subtract, do a point Merge.

Then select all n-Gons and Bevel 1 or 2 times with Shift=0 and Inset set to something near the radius you want for the edge curves using the Number Dialog.

Select all n-Gons, lw9 - lower right to "W" and SubPatch Weight - select menu "Map/Set Map Values" and set "Value1=100%". This blends Non-SubPatch (n-Gons) to SubPatched Polygons (along with Bevels). You may need to adjust n-Gon points on sharp curves if it pokes thru the edges.

Hit Tab.

Check SubPatch Weights in a Viewport by setting "Weight Shade".