Crash with certain DSC files - Nebula objects

[TimMc]

I am getting strange crashes when Celestia loads certain DSC files specifying Nebula objects, but not when it loads other objects that have been created in exactly the same way (same mesh, same sized texture files). I provide the link here to a small Add-On (~500K) of a few Messier objects specified as billboard Nebula objects, which I would be appreciative of others testing and seeing if the problem can be reproduced. The default setup for the Add-On as supplied below does NOT crash when Celestia loads it - you can safely load this and test it by targeting objects M1, M5, M6 and M13. However, if you exit Celestia and change the filename of M7.DSC.TXT to M7.DSC in the extras\deepsky_messierbillboards\ directory, then run Celestia, Celestia crashes during loading. Presumably there is something Celestia doesn't like about the M7.DSC nebula object specification. The same crash occurs when M8.DSC.TXT is changed to M8.DSC. Any suggestions on what is going on here, and how I can avoid the crashes?
Tim Mc
http://myweb.tiscali.co.uk/timmcmahon/celestia/messierbillboardstest.zip
Celestia 1.3.2rel8 and Celestia 1.3.1-1final, Windows 98, Intel P4 2.8 GHz CPU, 512MB RAM, 128MB nVidia FX5200

[selden]

Tim,

Unfortunately, I get a "file not found" when trying to download your file.
Maybe you made a typo?

Your /celestia/ page is protected against access, so I can't find it that way, either.

[TimMc]

A typo it was, Selden. I have corrected the spelling of the link - it should work now. And I must get my index page done for my web site done asap...

Regards, Tim Mc

[url]http://myweb.tiscali.co.uk/timmcmahon/celestia/messierbillboardstest.zip
[/url]

[selden]

Tim,

I'm sorry to say that both M7 and M8 work fine for me (after I remembered to type a "u" to turn on Galaxy display).

The only "problem" that I noticed was the capitalizations of the M8 filenames didn't agree, but that should be irrelevant under Windows. You should fix that so your Addon will be compatible with Linux and MacOS, though.

In other words,

Mesh "M8.3ds"
should be
Mesh "m8.3ds"

Also, you don't need to and shouldn't specify the Mesh and its orientation in both of the Nebula definitions that you're providing for each object. You can omit Mesh, Axis and Angle declarations from the second "short name" Nebula definition. That'll improve performance and reduce memory usage, since only one 3D object will be loaded into the graphics card for each Nebula. As it is now, two objects are being loaded and then both are being drawn at the same location.

Neither of these issues caused problems on my system, though.

Maybe it only happens under W98?
Or were you doing your tests with other Addons loaded at the same time?
I did my tests with only your test Addon in the Extras directory.


System configuration:
512MB 2.4MHz P4, WinXP Pro, SP1
128MB FX 5200, drivers v56.72
Celestia v1.3.1 final & v1.3.2pre8

[maxim]

I neither had any problem with m7 and m8, beside they're looking a bit odd rectangular.

maxim

[TimMc]

Thanks for testing this add-on, Selden. I am relieved the crashes are not reproduced on your system - it suggests the problem is with my Celstia configuration, or maybe even hardware. I have recently updated Celestia to version 1.3.2rel8 - I did not uninstall rel5 first, so maybe there are some registry conflicts. I have also added some extra RAM to my machine recently, and I suspect that it is defective. So I will do a clean install of Celestia and test the add-on again, then remove the extra RAM if I still have a problem.
I am about 80% complete on the Messier object billboards add-on, having collected all 110 Messier object image files, prepared all the billboard 3DS models, and begun the laborious process of documenting credits for each image. I have processed 20% of the DSC files to align the billboards normal to Earth - and it was when doing this that I started getting the crashes mentioned above. Your testing gives me confidence that others will not experience the problems I have had, and so I will get on with completing the DSC files so that I can release the add-on. Thanks again.
Regards, Tim Mc

[selden]

Tim,

FWIW, I usually just rename the directory Celestia (containing the old version) to have a different name and then install the new version, letting it recreate the directory Celestia. I've never had any registry problems when doing this, and it also makes it easy to run previous versions to test problems.

Sometimes intermittant memory problems are due to poor seating and can be fixed by unplugging the SIMMs and plugging them back in again. Other times the SIMMs need to be replaced.

I trust you verified that the new memory has exactly the same specs as the memory already in the system.

Another caveat with regard to the complete Messier catalog: be sure to include a warning about the size. People with graphics cards with less than 128MB will not be able to load all of the JPEG images at once.

[TimMc]

Thanks for all the advice, Selden. I renamed my existing Celestia directory and installed Celestia 1.3.2rel8 as a clean install, copied the Messier billboards add-on to it, and voila! the add-on works with no problems! I will now just copy the rest of my add-ons from the old Celestia to the new one.
On the other issues, my new memory does match the existing memory, is seated correctly, but does seem to have some defect as the Norton Hardware diagnostic fails it. But it does not seem to be affecting the new Celestia install, so I will persevere with it.
I am very aware of the rendering and graphical memory issues when many objects with large textures are loaded in Celestia, and will release the add-on with suitable health warnings.
Thanks for your help - much appreciated. Tim Mc