Celestia Forums

I think many of youll agree that weather effects would add tremendously to the realsim of celestia. imagine lading on venus, looking up at the cloudy sky and seeing lightning stike nearby with an accompaningy thunderclap. all this followed by a steady downpour of acid rain.

Maybe when everyone's got a supercomputer on their desktop... til then, while it'd be cool, it's probably way down on the list of priorities!

Oh Evil One,

While randomized weather might be computationally intensive, looping animations might not be. Chris has mentioned once or twice that he's hoping the new CMOD model format will be able to support some kinds of animations, although the code to support it does not yet exist.

I don't know a huge amount about what real-time meteorological data is available on-line but wouldn't it be great to be able to display real-time cloud patterns/ storms etc on Earth?

Weather would be hard, they had to model every single cloud in Flight Simulator 2004.

Nope, for CELESTIA wether is not a so big thing like for a Flightsimulator (you are not near 90% of the Time in the cloudes but ca. 90% in space).

I would say that ca. 3 cloude layers (sequence animated) plus some good sprite animations(lightning) could do the trick ( as viewed from space) perfectly.

Inside the athmosphere things get more tricky:

Cheap crapy version:
Use sprites for rain and lightning like the trees in older games made out of 2 til 4 instances of the same image put together with a rotation offset.

Pro: easy to make (code) run on all computers (no need for a better CPU/GPU)
Con: hard work to get somting like good looking

The real way to this IMHO would be to use Particlesystems (like fire, rain and snow in new games). I do not know how to do a lightning with Particles but I know it is possible. It is the real way for making it rain and meybe with a realy clever algorithem the cloude textures could be used as base to render them with a fitting Particle "cloude" to add volume to them. Imagine 3 animated layers of cloudes from outside of the athmosphere.
From the Inside, the same three animated layers geting lost (or geting replaced) in the Particlehaze wich forms the closeup 3D clouds (say: use the pixel color as particle color; use the pixel darkness as cloude tickness; use the pixel transparency as particles per m^3)

Pro: Things would look better (if properly implemented same thing could be used for Comettails, Nebulas, Galaxies (aren't they particles yet?), Blackholedisks .........)
Con: harder to code (i think) and more resource demanding

PS: Microsoft is stupide no wonder they modeled the cloudes by hand in Flight Simulator 2004. With one layer for the ground haze and 4 to 5 cloude layers, a colorcode for cloudetype and a algo witch consider the cloudetype and uses some fractal interpolation (outer and inner form) they could have paint there clouds in 2D and animate them in 2D on 4 to 5 layers with the result of on the fly 3D rendered 3D animated clouds.
What do you think is easyer: 3D modeling and animation or 3D modeling and animation? And witch methode would you use if both look the same in the end?

Implementing nodes in Celestia can accomplish this. This would however require one to add into the cmod format a plugin that exports from such as 3d studio or anim8tor In 3d studio there are helpers known as points. These points can be assigned a label such as sp_anim_lightining01 sp could represent that its a sprite. anim could represent it requires several frames from an image to display and lightining could designate a reference in a sprite table. You could also just have several exported single point cmod files and insert them in the atmosphere of the planet. Or one cmod file with points in a sphere each assigned different references to lightining. 01 02 03 etc... Each having different variables.

The sprite table could be such as sprites.spr

lightining01 {
Color [ 1 1 1 ]
Texture "lightining.jpg"
FrameSize 64
FrameCount 4
Seed 12345
Rate 10
RateInc 3
}

lightining02 {
Color [ 1 0.8 1 ]
Texture "lightining.jpg"
FrameSize 64
FrameCount 4
Seed 55453
Rate 8
RateInc 1
}

lightening jpg would be a 128 x 128 texture containing 4 64 x 64 frames for the lightining animation. Seed could be the random seed for playback. Rate is the base rate it playbacks and could vary using Rate Inc no more than -3 to +3 seconds.

Also with something like this you could create a galaxy using these points in varying depths of color and texture. I could see this affectively being used on standard machines with the proper use of textures. This would require tedious work on the part of the artist though. Unless one were to fashon a galaxy rendering platform that created these on the fly and allowed you to edit the color and texture and export to cmod. 3ds would not work as 3ds doesnt allow points...sadly.

Are you focusing on sprites? Sorry english is not my mother language

And how about animated raster images (cloude map) based Particles?
I think it would be easy for artists to make them cuz from distance they would be what they are Images (apart from spezial lightning pixels/(wether layer) where rendomly lightnig can ocure).
The clou comes in closeups where the same images geting trancformed into clouds with volume for no extra work to do by the artist, so he can make cool 3D clouds in a 2D standart program like gimp or paint

What is with this nodes and points concepts?

Why are you focusing an 3d studio?

PS: Take a look at blender3d.org (opensource 3d and more)

Ras',

Celestia v1.3.2 pre3 and later already support points in CMOD models. That's how I did the high-redshift quasar and galaxy models.

My understanding is that the things you mention are avaiable by using the OpenGL routines ARB_point_sprite and ARB_point_parameters. Hopefully they'll be available in CMOD models in the not too distant future.

Seeing moving flares on the Sun would be nice also..