Coloring a circular region on a sphere?

I have something that intuitively “feels” like it should be simple, but I’m having a great deal of trouble implementing. I’m trying to do some very simple “comic strip”-style cartooning… characters with spherical heads, protruding spherical eyes/noses/ears, cylindrical bodies and limbs, etc. The most basic style imaginable.

What I would LIKE to have is a simple circle-type shape for the character’s mouth… some black circular shape, superimposed onto the spherical head like the “Great Red Spot” on the planet Jupiter. I would then increase and decrease the black “circle”'s diameter to animate the character speaking.

Unfortunately, what sounds simple on paper has turned out to be more complicated in practice… particularly for a Blender-newbie such as myself! I started out trying to create a “Circle” mesh to work with. This brings me to my first question… why doesn’t a circle mesh have a face? I wasted untold amounts of time trying to apply material to a circle, but I’ve reached the conclusion that this mesh type simply isn’t intended to have faces. I ultimately figured out that a workaround is to create a cylinder, then delete the vertices on one of the circular ends… leaving behind a 2D circle with a face. Still, this was bizarre… unless I’m really missing out on something, the “Circle” seems to be an almost worthless mesh type.

It didn’t take me long to realize that having a 2D circle wasn’t going to be of any help to me, as I could find no graceful way to “bend it in place” around the spherical head and form a truly 3D “spot” on the sphere’s surface. I decided to try a different approach altogether. I created a UVSphere, and duplicated it. On one duplicate, I removed a few rings from the sphere (as if slicing the Arctic Circle off a globe). On the other duplicate, I removed the exact inverse. I added flesh-colored material to the large sphere, and pitch-black material to the small “mouth” slice. I then positioned the slice over the gap in the large sphere, and joined the objects together. After rotating the object to bring the black area to the lower-front, I have a fleshy cartoon head with a small black circular mouth.

This looks okay for a single frame rendering, but it really isn’t that good for animation. I have no way to scale and change the diameter of the “mouth” without deforming the entire head, so my cartoon character can’t “talk” in animations.

Does anyone have any suggestions for a better technique I could be using? What I basically need is to take a “globe” with lattitude and longitute (a UVSphere), and blacken one of the “polar regions” from a certain lattitude on up. I then need to easily increase or decrease the lattitude of the blackened region… effectively enlarging and shrinking the diameter of the area when viewed dead-on from above.

A circle mesh is a circle of vertices and their edges = no faces to render. You can extrude the whole circle and scale the new verts to the center to 0.000 then remove doubles, or select any 2 verts and hit F to create an edge repeatedly until all verts have > the original edges. Then select verts in groups of 3 or 4 and hit F to give them faces.

For your mouth: you can use an animated texture (gif avi etc) or you can keep the black mouth you describe and use RVK (relative vertex keys) to animate it. Lots of learning but you knew that getting into Blender. Look in my sig for IamInnocents tut on RVK’s and in the tutlist at the top of the page. If you want to do all your learning in one go search for ‘lipsync’.