New billboard technique

[Cham]

I was never satisfied with the billboards in Celestia. Many of them are showing a texture mapped on a curvy surface mesh (to crudely simulate some depth effect), or on a simple flat board with some apparent thickness around the edge (crushed cube). In the later case, there's a texture deformation around the thickness (most billboards from Selden are like this). So I designed a CMOD flat billboard which does not have any thickness at all, and which displays a nice frame without thickness around the main body. The texture, transparency and frame color can easily be edited with a text editor. Here are the Pleiades as an example :

pleiades.jpg

Personally, I think this is much more satisfying than a curvy billboard or a flat one with some thickness and without a frame. Here's the addon (toggle script included). I also identified all nine pleiades stars (the "seven sisters" and their parents) :

Pleiades.zip

I think that most flat billboards should be defined as invisible objects, which can be turned ON on demand using a specific CELX script, like in the addon above.

The billboard itself is a simple text CMOD file that can be edited very easily :

Code: Select all

#celmodel__ascii

material  # Texture definition
   diffuse 1 1 1
   opacity 1
   texture0 "m45.jpg"
end_material

material  # Weak orange for the frame
   emissive 0.45 0.35 0
   diffuse  0.45 0.35 0
   opacity 0.7
end_material

mesh  # Flat billboard with a texture

vertexdesc
   position f3
   normal f3
   texcoord0 f2
end_vertexdesc

vertices 8
-0.5 0 -0.5 0 -1 0 0 0
-0.5 0 -0.5 0 1 0 0 0
-0.5 0 0.5 0 -1 0 0 -1
-0.5 0 0.5 0 1 0 0 -1
0.5 0 -0.5 0 -1 0 1 0
0.5 0 -0.5 0 1 0 1 0
0.5 0 0.5 0 -1 0 1 -1
0.5 0 0.5 0 1 0 1 -1

trilist 0 12
4 6 0 6 2 0 7 5 1 3 7 1

end_mesh

mesh  # Frame definition
 vertexdesc position f3 end_vertexdesc

vertices 4
0.5 0 0.5
0.5 0 -0.5
-0.5 0 -0.5
-0.5 0 0.5

linestrip 1 5
0
1
2
3
0

end_mesh


[Cham]

I made two more similar addons, for the beautifull galaxies M51 and M101 :

galaxies.jpg

There's a switch that let the user to turn ON/OFF the billboard, on demand (while switching back the standard galactic model from Celestia) :

galaxies2.jpg

This is very handy to do some comparison and the educational value should be very strong.

The textures used are pretty large, so I can't publish the addons here.

[t00fri]

I made two more similar addons, for the beautifull galaxies M51 and M101 :

galaxies.jpg

There's a switch that let the user to turn ON/OFF the billboard, on demand (while switching back the standard galactic model from Celestia) :

galaxies2.jpg

Martin,

this is really a most strange display of the "standard galaxies from Celestia"! I assume you know meanwhile how to display the Celestia galaxies properly. It is not exactly a fair comparison what you did above. Here is e.g. how M 101 looks in Celestia:



Fridger

[Cham]

Fridger,

your comment is pointless. In Celestia, the user has the right to go to the galaxy, to see it at close range. The user isn't confined to Earth. So ...

[t00fri]

Fridger,

your comment is pointless. In Celestia, the user has the right to go to the galaxy, to see it at close range. The user isn't confined to Earth. So ...

That was NOT my point. My above image of the standard m101 from Celestia is how the galaxy looks from Earth. I rather think that -- by displaying such lousy comparison images of the standard galaxies in Celestia-- you actually attempt to create more interest for your billboard stuff...

Fridger

[Cham]

... and why do you care ? You're not even interested in addons.

Enough interaction with you.

[t00fri]

... and why do you care ? You're not even interested in addons.

Enough interaction with you.

But I am interested that the standard galaxies in Celestia are not exhibited in a lousy manner, since I coded them... Such displays would serve as a totally misleading introduction to Celestia newcomers.

No need to answer!

Fridger

[ElChristou]

Funny!

[Reiko]

First of all I like those billboards, they look great Cham.

t00fri, is the fact I'm not looking at those galaxies from earth why they never seem to render the way you said they should?

[Hungry4info]

First of all I like those billboards, they look great Cham.

t00fri, is the fact I'm not looking at those galaxies from earth why they never seem to render the way you said they should?

It seems to me that the farther you are from a galaxy, the better you can get it to display.

Cham, nice work =). I'm not entirely sure the border visually works well though.

[t00fri]

First of all I like those billboards, they look great Cham.

t00fri, is the fact I'm not looking at those galaxies from earth why they never seem to render the way you said they should?

Reiko,

if you are interested, I can teach you how to achieve the optimal display settings for the standard Celestia galaxies, both from Earth and from any point in space. It is quite simple.

Incidentally, I think the shape of a magnifying glass would be preferable to a billboard...
Unlike a billboard, it's purpose would be self-explanatory...

Fridger

[Reiko]

First of all I like those billboards, they look great Cham.

t00fri, is the fact I'm not looking at those galaxies from earth why they never seem to render the way you said they should?

Reiko,

if you are interested, I can teach you how to achieve the optimal display settings for the standard Celestia galaxies, both from Earth and from any point in space. It is quite simple.

Fridger

Yes I'm interested, I would appreciate it very much.

[t00fri]

First of all I like those billboards, they look great Cham.

t00fri, is the fact I'm not looking at those galaxies from earth why they never seem to render the way you said they should?

Reiko,

if you are interested, I can teach you how to achieve the optimal display settings for the standard Celestia galaxies, both from Earth and from any point in space. It is quite simple.

Fridger

Yes I'm interested, I would appreciate it very much.

Reiko,

in order not to steal Cham's thread with this, I did the explanation here:
+++++++++++++++++++
viewtopic.php?f=2&t=13348
+++++++++++++++++++

Enjoy,
Fridger

[Vincent]

Martin,

Here's an optimised version of your pleiades.celx script. It would be very handy for scripts localisation
to get used to define the localized names of objects in a table, and also to gather all togather the text
strings that need to be displayed. The following script does this:

Code: Select all

-- Title: Pr?senter les Pl?iades (M45)

function rgb2hex(r,g,b)
   -- Converts color code from RGB to Hex
   local hex = string.format("#%.2x%.2x%.2x", r*255, g*255, b*255)
   return hex
end

Pleiades_t = {
    "Alcyone",
    "Atlas",
    "Electra",
    "Maia",
    "Merope",
    "Taygeta",
    "Pleione",
    "Celaeno",
    "Asterope"
}

Pleiades_Loc_Names_t =
{
    Alcyone = "Alcyone",
    Atlas = "Atlas",
    Electra = "?lectra",               
    Maia = "Ma?a",
    Merope = "M?rope",
    Taygeta = "Tayg?te",
    Pleione = "Pl?ion?",
    Celaeno = "S?l?ne",
    Asterope = "Ast?rope"
}

Text1 = " Les Pl?iades (M45).\n « Les sept soeurs », filles d'Atlas et de Pl?ion?."
Text2 = ""

for k, starname in pairs(Pleiades_t) do
    star = celestia:find(starname)
    star:mark(rgb2hex(0.55, 0.55, 0.8), "circle", 18, 1, Pleiades_Loc_Names_t(starname))
    wait(0)
end

M45 = celestia:find("Pl?iades")
M45:setvisible(not M45:visible())

if M45:visible() then
    celestia:select(M45)
    celestia:getobserver():center(M45, 1)
    celestia:print(Text1, 5)
    wait(1)
    celestia:setrenderflags { nebulae = true }
    celestia:setrenderflags { markers = true }
else
    celestia:setrenderflags { markers = false }
    celestia:print("Text2", 1)
    for k, object in pairs(Pleiades_t) do
            Pleiades = celestia:find(object)
            Pleiades:unmark()
    end
end