Claudia Herbst-Tait
Professor
Department of Digital Arts
Pratt Institute


Borrowing UVs from NURBS Objects to Simplify the Texturing Process of Cylindrical Objects


Open the file extrude_along_path.mb. In it, I placed a cylinder and a CV curve. You will start this process by
extruding the cylinder's bottom face along the path. To do so, select the poly face, shift-select the curve
(as depicted in figure 1).


figure 1



Go to Edit Mesh, Extrude, options box -- use default settings. The result should look like this (figure 2).





In the Channel box, you see the polyExtrudeFace1 node attributes; scroll down and set Divisions to 30,
and Taper to 0, as indicated in figure 3.


figure 3



The result should look like this (figure 4).


figure 4



Now select the face at the thin end of the object as indicated in figure 5. Delete it.


figure 5



Next, select the top face at the thick end of the shape as indicated in figure 6.





Go to Mesh, Extract. You now have two separate objects, the top face and the cylinder. It should look
like this (figure 7).


figure 7


From now on, we're only dealing with the cylinder (not the top). Let's quickly apply a texture to this object
to see what it looks like (figure 8).


figure 8



OK, so the texture is hideously stretched... The following steps are about borrowing UVs from a NURBS object.
Why go through this process? UV mapping this poly object would be no fun as none of the standard UV mapping
techniques would be helpful here. We'll start with some conversions...

Select the cylinder, go to Modify, Convert, Polygons to SubDiv. Next convert the SubDiv object to a NURBS object
making sure to use these settings (figure 9).


figure 9



In the Hypergraph, select the subdToNurbsShape1 node, midlle-mouse button click and drack it
out of its group. Now delete the original pCylinder1 node, the curve1 node and the polyToSubd1 node.
You should be left with only the subdToNurbsShape1 node -- select it, open the Attibute Editor.
Take note of the Spans UV numbers, 16 in U and 62 in V (figure 10). Because the object has gotten
pretty complex, in the next step, we will use half those values (8 in U, and 31 in V).





With the object still selected, switch to the Surfaces module. Go to Edit NURBS, Rebuild Surfaces,
options box. Use the following settings (figure 11) and click Rebuild.


figure 11


Now convert the NURBS object back to a Polygon -- in the options box, make sure to select Control Points.
In the Hypergraph, delete the NURBS node.

Go to Display, Polygons, Border Edges. You should now see that your poly object has an open edge along its
length (you might have to move the camera to the back of the object to see it). It should look like this (figure 12).


figure 12



Select the edges along the length of the cylinder only -- you can double-click on it while in select edge mode
but make sure to deselect the edges along the top/opening of the shape as depicted in figure 13.


figure 13



Switch back to the Polygon module. Go to Edit Mesh, Merge, options box. Use these settings (figure 14).
Click Merge. The shape should now be closed (no more open border along the length of the cylinder).


figure 14



Let's apply the our texture again (you can also use Maya's checker texture)-- it looks better
than before but still needs a bit of work...In the UV Texture Editor, scale the UVs so that it looks
something like this (figure 15).


figure 15



Once you find what looks like the right scale amount, cut the UV shell into piece so as to maximizethe UV texture space.
It should look something like what you see in figure 16.


figure 16

Remember we extracted the top of the cylinder earlier? You can now attach it again by merging the verts and use a
planar map on these faces.

Voila!