Go-to approach too fast

General discussion about Celestia that doesn't fit into other forums.
Topic author
Marty
Posts: 15
Joined: 12.09.2006
With us: 18 years 2 months

Go-to approach too fast

Post #1by Marty » 12.09.2006, 12:57

When moving from one planet to another the approach at the end is too fast. On some systems the image hangs until the buffer fills then abruptly fills the screen with planet.

Needs to be deaccelarated more gently. Or better, have some control that we could customize approaches.

Marty

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selden
Developer
Posts: 10192
Joined: 04.09.2002
With us: 22 years 2 months
Location: NY, USA

Post #2by selden » 12.09.2006, 13:06

Marty,

The hiccup happens when textures are loaded.
If you go back to the starting point and do another GoTo, it'll proceed smoothly.

You can add "preloadtex" commands to the startup script (start.cel) if you want. It already includes some for the Earth. They cause Celestia to load the specified textures when it starts rather than waiting until the object comes into view. The preloadtex process isn't perfect, though: it doesn't load every texture that might be needed.

Celestia currently uses synchronous I/O, which also is called being "single threaded". This means that it only does one thing at a time. It waits for disk I/O to complete before it updates the screen. Maybe someday it'll become multithreaded and/or use asynchronous I/O. Then the type of pause that you see wouldn't be quite so obvious. (But planets might look like white balls for a while until their surface textures have been loaded.)
Selden

Topic author
Marty
Posts: 15
Joined: 12.09.2006
With us: 18 years 2 months

Post #3by Marty » 12.09.2006, 23:29

Thanks

Makes sense.

I note too that on some 'slower' systems the animation is smoother.

On my old desktop w/-Celeron 660Mz + Open GL + NVidia TNT64 frame rate is faster than om my newer notebook with AMD Sempron 2Ghz + 500RAM

Marty


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