Discussion: Eyeballs, optimisation and poly counts

[Artician]

I just posted something on this topic in another forum yesterday:

<cut>/<paste>

"About your question on his eyes:
Model the spheres of his eye right into his face, so that the eyeball itself is part of the facial mesh. Then texture the eyeball along with the main facial mapping, and make sure to only texture them white.
Then texture his iris onto a flat plane that is separate from the rest of the eye. Place the iris plane just over the geometry of the eyeball. When you want to animate him looking around, just rotate the planes of his eyes to simulate the motion.
You'll have to make sure the planes follow the curvature of the eyeball by moving the pivots of the iris planes to the center of the eyeball geometry.
This is a great technique to use, but it's different from the traditional method of modeling the eye sockets in the face and then placing a rotating sphere into them. You save a lot on poly count.

[Asorson]

Geospheres are generally better for game modeling because 1) they are lower polycount and 2) they unwrap into a single tri-strip which makes it even more efficient for engines that support it, where-as a normal hemisphere is made up of several tri-strips capped off with a fan (bad news).

So always go geo.

Articians idea is good also, the only thing I would worry about is clipping. Not actual geometry clipping but the video card accidentally drawing one piece of geometry in front of an overlapping piece because they are too close together. Also during most eye movements the eyeball will go partially underneath the eyelids and you can't do that with this method.

[SecretAgent]

What exactly do you mean by "Geosphere," I've never heard of that before? I have a lot of trouble with making an eye especially when the eye is and oblong/stylistic shape and I would definetly love to hear your guys ideas how to work around this problem.

[CGmonkey]

Geosphere is basicly another topology of a sphere. I haven't found it in Maya but it's quite easy to get one in max. Just a checkbox in the sphere creation menu.

[Damm]

this is the difference :D..

http://shadow.krabbit.com/abbe_personal/sphere_geo.jpg

[SecretAgent]

ah, I see, it's constructed completely out of triangles. Thanks for the explanation.

[jacobt]

they unwrap into a single tri-strip which makes it even more efficient for engines that support it, where-as a normal hemisphere is made up of several tri-strips capped off with a fan (bad news). [/B]

so in the case of a cylinder, is it better to cap it off with more polys / no fan?

are all game engines similar in this respect?

cheers, this stuff is all very interesting :D

[RatPoiZon]

tessellated spheres - is what they are called in Lightwave, also quite easy to get through the Num pannel (Shortcut -> N)

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.