Interacting galaxies in full 3D ! ;-)

[Cham]

Here's a first model of a galactic interaction (from a super-computer simulation), rendered in Celestia. No sprites for the moment. This is just a prototype :

interaction.jpg

There are more than 475 000 particles in there, and the frame rate is VERY good on my system.

EDIT : The data are coming from this web site. See also the very nice animations there !

http://www.ifa.hawaii.edu/~barnes/pressrel/mice/

[t00fri]

Here is my corresponding video from Celestial Matters, due to Volker Springel@ MPI Garching:

http://www.mpa-garching.mpg.de/galform/ ... galaxy.mpg

Fridger

[Cham]

Here's another version with sprites only, after removing the blue particles shown above. VERY nice, in Celestia !

interact1.jpg

interact2.jpg

interact3.jpg

[Cham]

Here's a better version. Fully "sprited" (344064 blobs in this model). Click the pictures below for a much larger version :

galac1.jpg

galac2.jpg

galac3.jpg

[ElChristou]

Pretty cool!
FPS?
Could it be possible to colorize these models to get a fell similar to the default rendering? (bright core etc...)

[Cham]

The FPS is very good on my system. It's slowing down when I go inside a galactic core, but it isn't dramatic.

Unfortunately, the particles don't have an identity, so I can't give a different color to the galactic bulges (cores). The model is the result of some super-computer simulation, so each particle can fly all around (no "core identity").

Here's a link to the model. Please, I need some feedback about how it performs on your system, sprite quality, frame rate, etc...

http://fsgregs.startlogic.com/Public_Fi ... GC4676.zip (5.7 MB)

Note : to move well inside, just select and follow the barycenter called "NGC 4676 AB" (or select "Les Souris"). You will also notice the sprite luminosity problem at large distance. Chris ?

[selden]

Cham,

I don't know what you mean by "sprite quality".
I see square sprites. They might look better if they were round.
I get 60fps on my computer, both when viewing from a distance and from inside the model.

1GB 3.4 GHz P4-550, WinXP Pro SP3
256MB GF 7800 GTX, ForceWare v181.20
Celestia r4668 from svn

[Cham]

I see square sprites. They might look better if they were round.

HUH !?! Please, post a picture of what you see ! The sprites are perfectly round on my system. For example, here's what they are looking like, as seen from the inside :



URL Link :

cel://Follow/NGC 4676 AB/2009-03-11T10:40:43.72928?x=AAAAAAAArDXmrqXX4v///w&y=AAAAAABgX8zNjNakAw&z=AAAAAAAAKXj2JYTaBA&ow=0.548054&ox=0.490205&oy=0.464093&oz=-0.493917&select=NGC 4676 AB&fov=38.3007&ts=1&ltd=0&p=1&rf=382359&lm=2064&tsrc=0&ver=3

[ElChristou]

Got an FPS from 16 inside to 50 and more outside. Rendering is fine on my config except of course the crap on the distance.

[Vincent]

Martin,

I get 60 fps from outside the model. From inside the model, the fps rate
depends on what I'm looking at. If I'm looking at one of the galaxy cores,
I get only 20 fps. Otherwise, the fps rate stays untouched at 60 fps.

[t00fri]

I think the galaxies don't look right, since the sprite size does not fluctuate on a random basis unlike my galaxy rendering in Celestia... Similarly, the brightness of the sprites must be allowed to fluctuate.

Fridger

[ElChristou]

I think the galaxies don't look right, since the sprite size does not fluctuate on a random basis unlike my galaxy rendering in Celestia... Similarly, the brightness of the sprites must be allowed to fluctuate.

Fridger

Fridger, this is in no way similar to your builded galaxy code. It's just a plot of points with a sprite attached to them. Martin don't have any control on anything apart the database. To achieve a rendering similar to the one we have I guess some coding is needed to incorporate fluctuation of sprite size/brightness...

[t00fri]

I think the galaxies don't look right, since the sprite size does not fluctuate on a random basis unlike my galaxy rendering in Celestia... Similarly, the brightness of the sprites must be allowed to fluctuate.

Fridger

Fridger, this is in no way similar to your builded galaxy code. It's just a plot of points with a sprite attached to them. Martin don't have any control on anything apart the database. To achieve a rendering similar to the one we have I guess some coding is needed to incorporate fluctuation of sprite size/brightness...

The situation in add-ons is actually not too different, except that the sprite size and brightness must fluctuate. If this is not yet implemented then it should be done.

Fridger

[ElChristou]

The situation in add-ons is actually not too different, except that the sprite size and brightness must fluctuate. If this is not yet implemented then it should be done.

Mmh... probably...
All depends on Martin's ability and desire (mostly important!) to write a small program to mod these points...

[t00fri]

The situation in add-ons is actually not too different, except that the sprite size and brightness must fluctuate. If this is not yet implemented then it should be done.

Mmh... probably...
All depends on Martin's ability and desire (mostly important!) to write a small program to mod these points...

As you stated already: both in the code and in the add-on, there is some distribution of points to start. We used the PNG templates for the points, remember? The next step is simply to associate to each point a sprite. In the code, the fluctuation of the size is done with a very fast algorithm.
It's just a few lines, that are a bit tricky, though

Code: Select all

int   pow2  = 1;
   for (unsigned int i = 0; i < nPoints; ++i)
    {
        if ((i & pow2) != 0)
        {
            pow2 <<= 1;
            size /= 1.55f;
            if (size < minimumFeatureSize)
                break;
        }
     
     ...


But in any case in the add-on also a certain size must be prescribed for each sprite. So all one has to do is to vary that size each time a point is mapped onto a sprite. It is conceptionally VERY simple.

I have never looked really into the add-on scheme since I am not a fan of add-ons, as you know. But it can't be much different....

Martin's above plot looks dull, since the sprite's brightness does not fluctuate either!

Fridger

[selden]

I see square sprites. They might look better if they were round.

HUH !?! Please, post a picture of what you see ! The sprites are perfectly round on my system.

Herewith. Using your URL (which I had to edit. The spaces caused problems when copying it.)

[Cham]

I think the galaxies don't look right, since the sprite size does not fluctuate on a random basis unlike my galaxy rendering in Celestia...

This is false. The sprites size does fluctuate randomly. Did you even tried the model ?

At close range, the model does look better (like a real galaxy) than your Celestia galaxies !

[Cham]

Herewith. Using your URL (which I had to edit. The spaces caused problems when copying it.)

Selden, the squares are indicating that the blob.png texture isn't at its proper place (textures/medres folder). Check that you do have the proper texture correctly installed.

[ElChristou]

I think the galaxies don't look right, since the sprite size does not fluctuate on a random basis unlike my galaxy rendering in Celestia...

This is false. The sprites size does fluctuate randomly. Did you even tried the model ?

I guess Fridger haven't try; now it's hard to say if the sprirtes' size fluctuate from your screen shots. And I must confess I haven't spot any size difference even being inside...

At close range, the model does look better (like a real galaxy) than your Celestia galaxies !

Pfff... what a comment!
Now, if you can tune this model to have the look of defaults galaxies as seems to point Fridger with his piece of code, then yes we will have something to compare!

[t00fri]

I think the galaxies don't look right, since the sprite size does not fluctuate on a random basis unlike my galaxy rendering in Celestia...

This is false. The sprites size does fluctuate randomly. Did you even tried the model ?

At close range, the model does look better (like a real galaxy) than your Celestia galaxies !

If you need to make such rude comments then I won't post here anymore.

Once you manage to complete 10000+ of your colliding galaxies, you will start appreciating the average quality of my 10000+ galaxies

No I did NOT run the add-on (I don't run ANY add-ons as you might know) , but it is obvious from the above image that the fluctuation is way too small if it exists.

Fridger

PS: the square sprites are a familiar bug that can be easily removed.