headus 3D tools

[PrayingMantis]

How would you go about the 3/4 mirroring technique used to reduce space in game?

what I do is unwrapping my mesh with symmetry and then I cut the part I want to mirror.
You end up with a kind of 3/4 mesh, where just the last quarter is mirrored.

The issue I have is about overlapping these shells. Using the snap and stack tool doesn't work because it snaps from the shell boundary, and now the boundary is not the same but it shares the same uv topology.
There is a way to snap from a point by moving the whole shell?
I want to select a point from one shell and move the whole shell to snap to an other point.
Unfortunatly I don't know how to do that.

[headus]

Can you attach a pic or two to explain? I dont quite get what your specific problem is.

Phil

[PrayingMantis]

Hi Phil, here is the picture:



In video game there is a technique called mirror offseting. You are offseting the seams and mirroring only one part of the uvs.
The red line is the actual symmetry of the mesh, the green part is the seam offseted, and the blue line is the seams of the mirrored uv shell. The yellow area is what is actually mirrored, (there is two blue seams because I offseted the seams for the front and back, the character is bald and shirtless).
It allows to prevent the "rorschach" effect you could have by mirroring your uvs at the mesh symmetry, while still saving uv space by mirroring part of the uvs.

So my issue is that I don't know how to align the partial mirrored uv shell (the yellow area). The snap and stack doesn't work because it align from the shell boundary and not the extremes uv points. Because the shell are not the same it doesn't align correctly using this method.
Do you know any way of doing this?

The only way I found is to zoom extremely close to a point and move the entire shell, when the zoom is extreme it snap to points. Probably a dumb way of doing this

[PrayingMantis]

I found a smartest way of doing it.

After writing a thousands words I thought that a few pictures may explain it better.
So here it is.













Is there a way to choose which shell will be ontop of an other? That would simplify the process.
Thanks.

[GeoffRiley]

I'd just like to say that's a great process you've worked out there - I'm not sure you'd get any simpler than that unless Phil does some fancy programming for a partial stack.

I hadn't come across this technique before, probably because I don't have much to do with games production. But does it not just push the seam problem off to another point in the model?

Kind regards,
Geoff

[PrayingMantis]

Thank you, it is way faster than my previous method.
About the seams it does push the seams away but the seams is not a real problem by itself.
At the texturing stage when you are painting your diffuse, if you have a normal symmetry the details will repeat and will create a rorschach effect.
By offseting the seam you can prevent this effect and even create the illusion of a non mirrored uvs by adding details at the center.

The seams I created here is not carve in stone, you choose where you want to put it. For example it is common for a face to keep both eyes.
By offsetting the seam the symmetry is less noticeable when you create your texture.

[headus]

Wow, I didn't know about that technique either. Brilliant!

So what I'm going to try is to tweak the 'm' key so that, if there's no weld edges on that shell, it'll snap it to its twin. That should save you a heap of steps. Stay tuned ...

Phil

[headus]

So here's the tweaked 'M' key now working ... from left to right, the shell is flattened and made perfectly symmetrical with 'S', then the symmetry editing is turned off and one quarter is detached, next that shell is flipped with the left/right arrow keys, then finally its snapped on top of its twin with one tap of the 'M' hotkey.

Regarding the detaching of the quarter shell, you may want to consider turning off "Open Cuts in UV View" under the Edit Preferences. That way you wont have to worry about the UV changing when you cut edges adjacent to the shell boundaries.

Are you using the Win, Mac or Linux 32bit or Linux 64bit build of UVLayout? Let me know and I'll upload a beta installer for whatever you're currently using.

Phil

[PrayingMantis]

Thanks Phil,
It is way faster, and I didn't knew about the Open cut option.
About my version I'm on windows but I am using a really old version, didn't update for a while.

[headus]

Oh, OK ... you'll need to renew your support subscription to access the beta releases. Its US$50 to renew for another year, and there's a payment link on your uvlayout.com Support Details page.

I'll build and upload the Windows beta now so its there ready if you do decide to renew.

Phil

[headus]

The new Windows beta is now ready to grab from the Support Extras page.

Phil

[PrayingMantis]

Thanks Phil, I will renew my support these next day.