Another Beginner's Mapping Question

John B

John B

0
Another Beginner's Mapping Question

I'm new to Cheetah 3D but not 3D modeling (used Strata, Cinema 4D, Unity, and others). I've spent my first several hours just trying to get a material mapped onto an object. Unsuccessfully.

As you can see in the attached image, I can't seem to get a texture to cover an entire object, in the attached sample, two cubes with a bevel on one side. I made a cube, created a texture, and applied it to the cube. That worked, all six sides had texture on them. As soon as I add a bevel, one or more sides go blank. I've spent over two hours trying every possible UV setting and manipulation, but nothing I do will put a texture on those blank sides. I've deleted, recreated, and added the texture many times.

Obviously I'm missing something as this should be about the simplest possible thing to do. So my first attempt to actually use Cheetah has failed at step 1. Please help.
 

Attachments

  • Cheetah-Sample.jpg
    Cheetah-Sample.jpg
    19.2 KB · Views: 304
While all parametric objects have default UVs (exception: Polyhedra) you need a new mapping when additional geometry is introduced. In your case just call the UV-mapper tool and let the default cubic mapping do its work:

Cheers
Frank
 

Attachments

  • UVmapper.jpg
    UVmapper.jpg
    108.3 KB · Views: 288
frank beckmann said:
While all parametric objects have default UVs (exception: Polyhedra) you need a new mapping when additional geometry is introduced. In your case just call the UV-mapper tool and let the default cubic mapping do its work:

Cheers
Frank
Click to expand...

Not sure I understand what you're talking about. The attachment shows what it looks like when I select the UV Mapper tool. The texture gets that checkerboard look, and that's it. As you can see, it's already set to cubic mapping (I've tried them all). I don't know what to do with that checkerboard. When I close the mapper, it goes back to the way it was.

FWIW, the one on the right in your sample is what I was shooting for.

Update: Now I see that if I change the scale under the Mapping Geometry Transform to some odd values (45, 18, 1), it starts to look correct. Unfortunately, it's tricky to enter those numbers (select the value and type really fast before the value gets unselected), as opposed to just dragging the handles. I'd prefer the scale in this case to just be 1, 1, 1, so the texture covers each side once without tiling or scaling.

I just realized the scaling on the texture depends on the scaling of the object. Every time I scale the object, I need to change the scale on the texture? That's something I haven't seen before.

Update 2: Nope, scaling the texture didn't make a difference. It did in the UV Mapper, it looked correct. But when that's closed, it goes back to having a blank side. What I see in the UV Mapper does't appear that way when I switch back to modeling.
 

Attachments

  • Cheetah-Sample-2.jpg
    Cheetah-Sample-2.jpg
    177.5 KB · Views: 266
Last edited:
frank beckmann said:
Then scale the UV-mapper tool up till it meets the greatest dimension; and don´t forget to Write UV coords. :mrgreen:

Cheers
Frank
Click to expand...

Thanks. I didn't see the Write Coordinates button. Learning all these extra steps, like having to remap/rescale a texture any time an object's transform changes, is going to take some getting used to. This is one of many things I've found that are one click or automatic in other modeling programs that must be done manually in Cheetah.
 
John B said:
having to remap/rescale a texture any time an object's transform changes
Click to expand...

What? Where did you get the impression that you need to do anything with texture mapping if you move an object around?

Once you've set UV coordinates they are intrinsic to a mesh and live in their own local space. Transforming the object has ZERO effect on its textures. The only thing that forces changes to a UV map and/or textures are changes to geometry (in particular, adding or removing edges or faces).

When you create a polygon you need to tell C3D where (in space) its vertices are (i.e. are they pre-existing vertices or new vertices). When you do this C3D does not find out what those vertice's UV coordinates are, so it just sets them to some default value (0,0,0 I assume). But if you go map them explicitly they stay mapped.

There's no program in the world that can clairvoyantly determine what the UVs for new geometry need to be (although some can guess, and very high end material systems, e.g. there's one developed at Disney a few years back, simply map every face to its own texture space, so UV mapping is irrelevant).
 
Last edited:
You must log in or register to reply here.
Back
Top