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View Full Version : hum waht about the gloss map?


supernekosan
07-22-2005, 05:11 PM
okey i just got a litle question ...every body is doing difus map+normal map+ spec map...hum what about gloss map....is it used in game...because i particularly tink it add someting to a model if we add gloss to it.....but is it used normaly..or is it for next gen console??

tanx in advance^^

AdamAtomic
07-22-2005, 05:16 PM
I have been using gloss maps in my contract work. For this game it uses the alpha channel of the spec map. Gloss maps in general (from what I've been told) should almost never use a brighter value than what is in the spec map, and in general if you are using a gloss map you want to keep the total value of gloss + spec under 200 or so, to prevent huge washed out white areas in-game. Hope that helps!

Dargon
07-22-2005, 06:40 PM
I'm working for a next gen PC title, and we use diffuse, gloss, spec, normal, and about 8 other shader channels that I probably shouldn't talk about.

To tell you the truth, a flat colour is often good enough for most things for gloss. Usually a value of around 030,030,030 on a 1X1 pixel texture does the job. The only time you'd need a gloss map would be when there are many radically different materials on the object - like cloth and rubber.

three
07-23-2005, 11:13 PM
I'm thinking: Isn't specular maps and gloss maps the same thing? They both make stuff shine in certain areas, right?
Could someone elaborate what gloss maps are and do?

Thanks,
Marcus

Poopinmymouth
07-23-2005, 11:53 PM
Gloss provides a way to control falloff. Normally real life surfaces are either diffuse or glossy based on the surface grit, and the fact light in real life is perfect. In the games we dont' have that accuracy, so the gloss can make things look wetter or dryer without reducing the shine intensity. It just spreads it out or tightens it based on a grey value. You use it to help change up material types. Broad gloss on skin, tight on a mirror or metal, almost completely black on something like fabric or concrete.

KMan
07-24-2005, 04:46 AM
Marcus-

The values from a specular map affect how much of the light's brightness and color shine on an object.

The values from a gloss map would affect how sharp the highlight shining on the object would be.

three
07-24-2005, 04:52 PM
Great, thanks Poop and KMan for the clarification.

Confracto
07-24-2005, 09:59 PM
while we're on the subject...I've noticed some people have been using what looks like real time glow stuff on things..
what I'm wondering is, is this just in renders...or is there a real time shader with glow controls...and how is it controlled? gloss, or spec, or something else?

supernekosan
07-26-2005, 01:51 AM
i wanted to know someting too..is it possible to do a glow effect like that in a game..and if it is...what teknique should we use

http://img.photobucket.com/albums/v289/supernekosan/block%20buster/some-light.jpg

Dargon
07-26-2005, 01:57 AM
In higher end games (we calling them next gen right now for some reason - but I thought the gen we just finished was next gen :shrug:) You should be able to add a post process effect much like glow.

Previously how an effect like that would be made would be an alpha plane in front of the object, usually billboarding with it's pivot inside the object, so it always appeared in front no matter the direction you viewed it from.

Matt
07-26-2005, 02:32 AM
The sprite method is still viable, and certainly should be used in many scenarios. Falling back on special effects for every little thing just gives the GPU more stuff to do.

Headless
07-26-2005, 03:09 AM
Post-processing glows into games is not limited to next gen. The first time it was done was in Tron 2.0. You can real more on the subject here (http://www.gamasutra.com/features/20040526/james_01.shtml).

There's also ways of doing it with vertex and pixel shaders. This (http://collective.valve-erc.com/index.php?doc=1081854378-22165000) isn't the best example, but you'll get the idea.

Either way it's really more something that a programmer would implement rather than an artist, at least until next gen when artists will get more control over shaders.

KMan
07-26-2005, 01:40 PM
If you wanted to set up a glow like that in a render you'd either use a video post glow, using a luminance threshold, or photoshop to do it after you rendered.

Here's a photoshop plugin that achieves this effect-
http://photoshop.pluginsworld.com/plugin.php?directory=adobe&software=photoshop&plugin=205

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