Question on 3DS models

[Dollan]

Can *any* 3DS model be used? I know about nothing in regards to 3D modelling in any forum or program. So I am curious, is there any fundamental difference between the 3DS models used in Celestia, and those used in Bryce 3D or Lightwave or any other modelling program?

...John...

[selden]

Any valid 3DS model should be usable with Celestia.

Note my use of the words "valid" and "should".

Too many model makers don't pay attention to the surface normals. Celestia only draws surfaces if they face toward the observer. Many 3D display programs don't make this distinction and always draw all of them. As a result, many models that look OK with some display programs seem to have have holes in them when drawn by Celestia.

Also, some bugs were introduced when Chris rewrote the model code in Celestia v1.3.2 and added the CMOD format. Surfaces that have translucent textures applied to them aren't always drawn correctly.

Another problem is that models used for DSC objects aren't depth sorted. Instead, the surfaces are drawn in the order that they're declared in the model. As a result, depending on the viewpoint, facets that should be hidden behind others often aren't hidden, while facets that should be drawn sometimes aren't visible. Models used in SSC catalogs are depth sorted, however.

[Dollan]

Hi Selden...

Thanks for the answer. When I get a chance, I'll run some experiments. I do remember, early on with my Celstia experience, I had tried to render one of Jester's models in Bryce. While it worked, it appeared rather blocky, and certainly not like the smooth pieces of art that they are in Celestia! I'm hoping that other models won't "overload" (for lack of a better word) Celestia; I'll have to be careful and not use some of the huge 3DS files that are out there.

Thanks again!

[smbika]

Selden,

A cold and barren "I knew it" from me on the 1.3.2 3ds bug thing. When I went to 1.3.2 one of my 3ds models started looking a little transparent here and there. Sounds like a genuine bug which i hope is on the bug list.

Considering the swath of other enhancements and bugs to be tended to i do not expect this to change anytime soon, but it is good to know i was not crazy.

Thanks,
Sean