topic Re: Loft object orientation angle - How to rotate cross section in 3ds Max Modeling Forum

Loft object orientation angle - How to rotate cross section

truckexpert — Thu, 09 Jan 2025 17:07:34 GMT

I am trying to create a guard rail using loft (open for alternate method). It seems pretty easy, but the rotation of the cross-section and orientation seems impossible to control. Attached is a simple model of what I'm trying to do, and what MAX keeps doing "wrong." How do I make the guard rail be vertical, and follow the terrain as shown?

Any help is greatly appreciated!

Dave

Re: Loft object orientation angle - How to rotate cross section

MartinBeh — Fri, 10 Jan 2025 00:26:21 GMT

Loft is really old code, and rather annoying in how it deals with transformations...

For starters: Are the cross sections changing at all, or do you simply want to use them for their orientation?

Maybe the Sweep modifier on your path with one of the shapes as Custom Section is useful?

Also note that with Loft, you can either start with a path and then use "Get Shape", or you start with a shape and then use "Get Path" - I often found the latter to be more predictable. And once a Loft is created, you can go into sub-object mode to access the Shapes and adjust them.

Creating all splines (path and cross sections) in the same viewport to make sure their local coordinate systems are aligned might also help.

NB: You can create meshes just from cross sections - for that you create and place as many cross sections as you want (e.g. by placing them along a path) and then attach them all into one shape; add a CrossSection modifier and a Surface modifier and finish with a Smooth modifier (or some other modifier to fix the surface normals).

Re: Loft object orientation angle - How to rotate cross section

Casey_H_ — Thu, 27 Mar 2025 00:05:03 GMT

Rules for Sweeps/Lofts:

Draw the path in Top view. Always. (If it's supposed to run vertically, rotate it up afterward.)
Draw the profile in Front view. Always. (The profile will always run along its own LOCAL Z axis.)

Here is an example of a curb w/ gutter profile in LOCAL Front view. Notice the Z axis.

And here it is in WORLD Front view:

Don't you f*ing hate how the axes change between LOCAL and WORLD? I guess you could also say the profile will always run along its WORLD Y axis as well, but I learned about and think of Z as depth from the camera (of course) making it easier to remember, personally.

Memorize and follow these rules (or take time to methodically test and make your own rules), otherwise you will constantly be confused by how they turn out (well, I was at least lol) and then waste time rotating shapes, rotating pivots, or trying every setting to get lucky. This way is simpler and easier to remember for beginners, IMO.

Re: Loft object orientation angle - How to rotate cross section

ads_czechoj — Fri, 28 Mar 2025 16:40:52 GMT

Hi Truckexpert, you need to follow the steps provided by Casey.