Color / tinting of procedural (fluffy) galaxies?

General discussion about Celestia that doesn't fit into other forums.
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heath_rezabek
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Color / tinting of procedural (fluffy) galaxies?

Post #1by heath_rezabek » 21.01.2007, 01:16

I am wondering if there is a simple way to tweak the overall tint of the puffy procedural galaxies from a beige / grey to a bluish hue. Too much time spent in digital planetariums for me, I guess. :) Any ideas?

Thanks,

- Heath Rezabek

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t00fri
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Re: Color / tinting of procedural (fluffy) galaxies?

Post #2by t00fri » 21.01.2007, 01:24

heath_rezabek wrote:I am wondering if there is a simple way to tweak the overall tint of the puffy procedural galaxies from a beige / grey to a bluish hue. Too much time spent in digital planetariums for me, I guess. :) Any ideas?

Thanks,

- Heath Rezabek


I don't understand which galaxies you mean. Please be more precise. Always specify your Celestia version and the Hubble type of galaxies you are interested in! For me 'puffy' is meaningless given that there are 10000+ galaxies in Celestia.

Do you mean the elliptical ones? They have a more orange color than the spirals. Generally I have derived all colors from true color galaxy imaging. So spirals are always blue in the outer zones as it should be. The ellipticals MUST be more reddish/orange, since they are MUCH older than spirals.

So what is your problem specifically?

Bye Fridger
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heath_rezabek
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Post #3by heath_rezabek » 21.01.2007, 02:13

Ah, I understand.

I understand and respect the official striving for realism, and your views on fantasy space-art I've noted. That said, I would simply like to experiment. Where, then, is the coloration for The Milky Way set?

Respectful thanks,

- Heath

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t00fri
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Post #4by t00fri » 21.01.2007, 02:32

heath_rezabek wrote:Ah, I understand.

I understand and respect the official striving for realism, and your views on fantasy space-art I've noted. That said, I would simply like to experiment. Where, then, is the coloration for The Milky Way set?

Respectful thanks,

- Heath


Look in the source code file

src/celengine/galaxy.cpp

in the method

void InitializeForms()

i.e. on line 627...632

The color is set in the HSV color basis and then transformed with the method hsv2rgb to the RGB color space. This has a number of advantages.

That's for the spirals. For elliptical galaxies, the color profile in line 627 is then simply stretched out (with a scale factor) , which makes them more orange. See line 664ff.

Bye Fridger
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heath_rezabek
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Post #5by heath_rezabek » 21.01.2007, 02:41

Aha, so in the source code. That makes sense. Well, I'm unlikely to recompile the app just to play with galaxy color. :) Thank you for letting me know.

- Heath

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t00fri
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Post #6by t00fri » 21.01.2007, 02:43

heath_rezabek wrote:Aha, so in the source code. That makes sense. Well, I'm unlikely to recompile the app just to play with galaxy color. :) Thank you for letting me know.

- Heath


Compilation just takes a few minutes.

Bye Fridger
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