How to open and straighten a curve?

[ThE_JacO]

The length of a high order function like a nurbs curve isn't really something easy to calculate.
The easiest way is letting XSI's API doing the work for you.
In Python:
Application.LogMessage(Application.Selection(0).ActivePrimitive.Geometry.Length)

Will give you the length of the first curve in a selection.

[Lone Deranger]

wannabeArtist:

It would probably easier to do this in reverse. As in create a straight line spline with a sufficient amount of bezier knots and use the bend modifier with the correct offsets and bend axis to deform it into a circle.

[wannabeArtist]

Jaco,

That works like a charm! (Well, after I noticed the extra space in the line ;) That was my first ever scripting lesson for XSI, thanks a lot :)

Lone Deranger,

Thanks to you too, that will come in handy after I've done tweaking the details on the tire.

My idea is to make a row of polygons exactly as long (and wide) as the circumference of the current (car) tire and then take that to ZBrush, put on detailed geometry for a normal map and export that back. Since the polygon strip will be the correct length, I should be able bend it to a circle again, matching the tire size nicely :)

Perhaps not the easiest way to do this, but I'm kind of obsessed to try to do the detail work in Zbrush :)

[Lone Deranger]

Why not just model a good base mesh for the tire. Make sure the quads of the mesh are nice and square, give it some good UV's. Take the mesh into ZBrush and use it's Radial Symmetry features in conjunction with a good tile-able alpha of the tire's treads.

Actually, you don't even need ZBrush for this. I've done tires in the past where I painted the displacement maps in PhotoShop. It's easy to get good looking results real fast this way.

Don't make it any harder than it needs to be. :)

[wannabeArtist]

Thanks,

I will explore what you just told :)

The thing is, I'm kind of new to textures, UVs etc. I know the basics, but not much else and what comes to ZBrush, I'm a complete beginner - very eager to learn that, though :)

I got the idea to use it for this project, after I saw a great tutorial about making custom alphas here (http://www.youtube.com/watch_popup?v=usaGRlqZfy4). That looked so cool, I though it would be nice to apply a same sort of technique on the tires and learn a little ZBrush on the way.

But you're right, no point in making this too difficult. I just found a great reference image and I probably just paint the map using that.

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