How to make mesh/texture less transparent?

[meegja]

After a week of discovering Celestia, I decided to make my first add on: the BlueRed nebula. All is going well, except that it all stays way to transparent, see http://www.3dart4u.com/bluered.jpg ... texture is just one I made up
But how to make it less transparent? The stars are shining through the mesh/texture and I want to make that less. Thanx in advance for any tips!!

Menno
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My 3D Art can be seen on
http://www.3dart4u.com
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It can't rain all the Time

[selden]

meegja,

Unfortunately, Celestia does not yet "depth sort" deep space objects. They are simply drawn in a particular order compared to other objects. As a result, changing the transparency won't make any difference for stars.

Specifically,
grey galaxy blobs are drawn first
then the Celestial Grid
then Nebulae (in the order that Celestia finds the files)
then orbits
then stars, planets and other SSC objects, which are depth sorted.

As a result, stars and planets are always drawn in front of Nebula objects.

The transparency of a Nebula does change whether or not Galaxies, the Celestial Grid and other Nebulae are visible through it. This transparency is controlled by a grey-scale Alpha channel if one is included in the image file specified in the Nebula's 3DS model file: black is completely transparent and white is completely opaque.

Does this help?

[Guest]

The transparency of a Nebula does change whether or not Galaxies, the Celestial Grid and other Nebulae are visible through it. This transparency is controlled by a grey-scale Alpha channel if one is included in the image file specified in the Nebula's 3DS model file: black is completely transparent and white is completely opaque.

Does this help?

It does a bit .... cause what ever I try, I can net get an Alpha channel attached to a PNG file. I can get get a Layer on it but then still the image of the nebula is way to transparent. Also I can not get the image to get "bright": when it is used in Celestia, the nebula stays dull/not bright, even though it's bright to look at in Photoshop?

Maybe it's better to ask if there is a Celestia Texture Guide somewhere? I found one in the forum but that only covers the basic.

Thanx in advance!!!!

[selden]

Celestia does not yet provide a way to control the relative brightness of a Nebula. Currently that can only be done with varying the brightness of the image itself.

There isn't any extensive documentation for textures in Celestia because Celestia really doesn't provide any way to manipulate them. The support for Deep Space Obects was added very recently and is just the bare minimum.

FWIW, I use either NetPBM or ImageMagick to merge an Alpha channel into png images. Every once in a while there's an image that NetPBM won't do that for, and it'll stay opaque. It's obviously a bug in NetPNG, since ImageMagick has no problems with the same files.

The NetPBM command is

Code: Select all

pnmtopng -alpha grey-image.pgm color-image.ppm >masked-image.png

The ImageMagick command is

Code: Select all

composite -compose CopyOpacity grey-image.pgm color-image.ppm -type TrueColorMatte masked-image.png

(although composite isn't limited to working with ppm files)

For some reason, I find the NetPBM command somewhat easier to remember