New sprites based nebulae

[Cham]

I'm starting a new nebula projet, out of some old Mathematica codes I've done during the previous years. I intend to built something more precise, with *eventually* filaments and some rich internal structures, using the Legendre polynomials. I can't tell if I'll be successfull with this, but it's an interesting experiment anyway.

Here's a first draft :

nebula.jpg

Here's the model itself, placed around 82 Eri for testing purposes :

TestNebula.zip

Navigating inside (if you placed some planets, spacecrafts, etc) is fun.

EDIT : Nomore Legendre polynomials. I'm using the Beta distribution instead.
http://en.wikipedia.org/wiki/Beta_distribution

[John Van Vliet]

--- edit ---

[Cham]

looks nice
but i have a question
In both test1 & 2 cmod
there is a invisible cube

as to the mesh
it looks like it is a perlin noise function

The invisible cube is used to center the model. Without it, the model may have an apparent offset relative to the central object (a star, for example). With lots of random sprites on a spherical shell, the cube isn't really necessary, but it helps. It becomes especially important if the nebula has a non-spherical shape (which I'll try to do once I master the technique for ellipsoidal planetary nebula).

I know nothing about the perlin noise function. What I'm doing is to define a distribution of randomly sized sprites on a spherical shell (uniform distribution between some min and max sizes). The sprites are also randomly distributed on the surface of the sphere (uniform distribution) and on its thickness (gaussian distribution).

By weighting the various distributions for some specific positions, I could get non-spherical shapes. I'll also try to use the Legendre polynomials as statistical distributions, instead of simplistic uniform distributions on the sphere.

[ajtribick]

The auto-centre behaviour can be switched off for ssc objects but not dsc or stc objects. Kind of annoying, probably should take another look at that.

[Fenerit]

Cham, do you have taken into account the Voronoi tassellation?

[Cham]

Cham, do you have taken into account the Voronoi tassellation?

No. What's that ?

[Cham]

Here's another prototype (the oblate shape is intentional. Feels more "natural" that a perfect sphere) :

blob.jpg

Here's the model for you to play with. Just use the same SSC file as given in the first post.
The colors can easily be edited in the cmod file...

test.cmod.zip

[Cham]

The frame rate hit is large, if the model has more than about 10k sprites. So I'll limit myself to about 1000 or 2000 sprites.

Also, there's a rendering problem when the sprites are very large, as seen from the inside of the model : moving the point of view makes some blobs to appear or disappear suddenly, when their center is close to the screen's edge. This is annoying, and inevitable.

Anyway, here's another model, which I think looks very nice from its outside :

neb1.jpg

neb2.jpg

And here's the model itself (again, use the SSC given in my first post, as a test) :

test2.cmod.zip

[Cham]

Here's another model. Its stucture is very interesting, and I may have something great here. Very nice from the interior too.
Of course, the color is arbitrary and may be edited in the cmod file, since it's a pure text file :

test1.jpg

Test2.jpg

To test the model, use the same ressources as given in my first post (SSC and texture files) :

test.cmod.zip

[Cham]

Now here's a surprising result. I'm not sure yet if it's good or not :

colors1.jpg

colors2.jpg

colors3.jpg

[Cham]

Here are two other variations. The 3D effect is looking pretty convincing, in Celestia.

nebulae.jpg

[Cham]

Guys, I need your opinion. Here are five nebula models to be tested. Test1 is probably too dense. Test2 and Test3 are alike (some variations are a good thing), while test4 and test5 are alike and have more colors (test5 is more fluffy than test4).

Which one do you prefer, and why ?

NebulaeTest.zip

Just place the NebulaeTest folder inside your extras folder and start Celestia. Then type in "Test (test1.cmod)" up to "Test (test5.cmod)" to visit the nebula's interior (the white sphere is just there as a reference to be clicked on), and move also around the nebula's exterior.

Before doing more nebulae, I need to know how they are performing on other systems (frame rate, rendering quality, etc).

[fungun]

Not good with an ATI HD 2400. All drivers up to date.
Vendor: ATI Technologies Inc.
Renderer: ATI Radeon HD 2400
Version: 3.2.9704 Compatibility Profile Context
GLSL version: 1.50
Max simultaneous textures: 8
Max texture size: 8192
Max cube map size: 8192
Point size range: 1.000000 - 63.000000

Tim

[Cham]

Not good with an ATI HD 2400. All drivers up to date.

How old is that video card ? The sprites should work on most video cards from the last few years.

[Fenerit]

Cham, test4 is my favorite.

@Tim, your sprite's view looks like on my sistem with OpenGL 2.0 render path not active. It seem more like points mesh than sprites.

[Fenerit]

P.S.
Test4 looks like NGC 6751
http://hubblesite.org/gallery/album/nebula/pr2000012a/

[fungun]

Yea she's pretty old.
I went through every setting I could on the card and in Celestia.

Tim

[Fenerit]

Yea she's pretty old.
I went through every setting I could on the card and in Celestia.

Tim

Your card has all the requisites to run Celestia like a charm. OpenGL card specification is 3.1. Latest drives version is 11.8. Can I ask you which Celestia's version you have and how you do update it amongst versions. Maybe do you have missing some shaders?

[Cham]

I'm adapting the previous technique to rings as well. A first draft :

ring.jpg

[Hungry4info]

Very nice! Clear applications to ? Pic and Fomalhaut.