Faster animation object for star chart?

Nov 22, 2008 at 2:28 PM
I'm creating a star chart. I'm using the Sphere that was found in the sample app. I've turned down the number of triangles and stacks, but I've found that while animating 600 stars it is quite jumpy.

I'm wondering... is there any other type of object that would animate faster? I don't really need to have a true sphere I suspect since all the user is seeing is a simple dot that is maybe 2x2 pixels.

I suspect it could just be my method for animating that is slowing it down as well. :)

Any tips?
Nov 23, 2008 at 8:16 PM
What about using multiple spheres nested parallel inside of each other? You would have fewer stars on each one and it should give you a better 3d effect.
Nov 23, 2008 at 11:06 PM
I'm not sure that I understand... how would having multiple spheres nested help? Can you explain a little more? Keep in mind, this is my first ever attempt at 3d anything, so even though it may be a simple concept, I may just not be thinking properly yet to understand what you mean :)
Nov 24, 2008 at 3:14 PM
If this library works the same way that WPF 3D does, the more triangles you have, the more work has to be done (every object is created from one or more triangles of various sizes). To get a fairly round sphere (as opposed to faceted), you need lots of triangles. I'm not certain how the many triangles the sphere example has. What you need to do is minimize the number of triangles you are using. I'm assuming some will be empty (no star) and some will have a star.

If I'm wrong, I'd be happy to be proven wrong.
Nov 24, 2008 at 7:21 PM
Ok, I agree with you on that point about the more triangles, the more work.

In my work so far, if there is no star, I don't load a sphere for it. The only time I load a sphere is when there is an actual star there to represent. I've got my stars now being represented by 4 triangles - from a distance, it looks fine. They appear to be points of light and nothing more. When the user zooms in close though, it becomes obvious that they are diamond-shaped.

It some of the old-school "3d" games (Doom perhaps?), it seems like I recall seeing something funky. The developers made the game render a flat object that appeared the same no matter what angle it was being viewed from. In this case, if I could simply draw a circle, then show the circle regardless of angle, it would work out I think.

So... is there a way to do this? Instead of rendering a sphere, render a flat 2d circle?

Also, I still don't understand the sphere nested in sphere concept and how it would work here. :)
Nov 24, 2008 at 7:41 PM
Since stars are different distances away from each other, when you change position, the ones closest to you appear to move more than the ones that are farther away. You can simulate this by have concentric spheres. The stars on the largest sphere would appear to move less than the ones on the smallest sphere.