Re: [Celestia-developers] patch with comet code, a new appMag sorted label display, ...fixes

[Fridger S. <fri...@de...>]

Sorry,

I just noticed that everything is fine if the comet is e.g. associated 
with tau Boo A.  Then after selecting the barycenter tau Boo or the 
secondaty tau Boo B, the comet is still found via command completion.

Bye Fridger
---------------------------------------------


Fridger Schrempp wrote:
> Hi,
>
> I attach a patch for testing before I commit it. It contains the 
> following items:
>
> 1) A neat scheme generalizing the sun distance x0, where comet tails 
> start fading, to systems with possibly /several suns/ and luminosities 
> different from the solar one! More detailed explanations and a 
> derivation for the x0 scaling law, x0 ~ sqrt(L/L_sol)* x0_sol,  you 
> find in my separate mail of yesterday.
>
> I include below a test file of a ficticous comet in the tau Boo A,B 
> system that gets close to tau Boo B and tau Boo A , respectively, 
> along it's orbit. One may watch nicely how the tail becomes visible 
> for distances < 0.43 AU from tau Boo B and < 9.1 AU from tau Boo A 
> (the difference reflects the huge luminosity difference of A and B). 
> In addition, unlike Chris' original code, the tail now aligns towards 
> the sun with the /dominant/ light irradiance, as it should be. Apart 
> from decreasing the overall shade intensity of the comet tail, I did 
> not modify Chris' basic comet rendering code (yet). Of course, comets 
> tend to develop 2 tails which needs further work...
>
> Here are once more two composite JPGs, illustrating some of these issues:
>
> http://www.shatters.net/~t00fri/images/comtest1.jpg
> http://www.shatters.net/~t00fri/images/bincomets.jpg
>
> -------------------------------------
> "Halley2" "TAU Boo"
> {
>    Class "comet"
>    Mesh "halley.cmod"
>    Texture "asteroid.jpg"
>    Radius 7.6 # maximum semi-axis
>    MeshCenter [ -0.338 1.303 0.230 ]
>    Albedo 0.05
>
>    EllipticalOrbit {
>        Period          100.31589
>        SemiMajorAxis   27.834144
>        Eccentricity    0.807143
>        Inclination     102.4
>        AscendingNode   161.7
>        MeanLongitude   176.5
>    }
>
>    Obliquity             102.4 # guess, to match inclination
>    EquatorAscendingNode  162 # guess, to match ascending node
>
> }
>
> ---------------------------------------
> Actually, the comet had to be assigned to the baycenter (tau Boo). It 
> may be located/selected in the  command line after  selecting  'tau 
> Boo', yet  it's  NOT  found  after  a selecting  tau BOO A,B'. That 
> has to be improved...
>
>
> 2) A new simple scheme avoiding overcrowded galaxy labels:  They are 
> now sorted  according to /apparent  magnitude/!  So  going e.g. to the 
> M 91 region, and zooming in with SHIFT+ mouse Left, you now see 
> /first/ all the bright Messier objects appearing before the dimmer NGC 
> labels show up! That's neat.  Also after startup, one sees only those 
> labels for objects visible according to the actual faintestMag 
> settings. By increasing/decreasing faintestMag ([ ] keys!), more/less 
> labels may be made visible at any time.
>
> 3) I dimmed the brightness of galaxies if viewed from /"inside"/, like 
> the MilkyWay, quite significantly...
>
> 4) I fixed a bug (spotted by Frank[fsgregs]) that /Nebula/ add-ons 
> vanished if viewed off the screen center. It's a clipping error, of 
> course due to the /huge/ size differences of Nebulae and Galaxies.
>
> 5)  There  was a  bug in Chris' recent commit  which  didn't compile. 
> That's fixed, too.
> That sort of thing (star.h)...
>
>                            inline const Star* getOrbitBarycenter() const;
>                            ...
>                   
> Bye Fridger