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trouble with alpha channels in Photoshop 5.0

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2 comments, last by Hase 24 years, 1 month ago
I´m having problems modifying the transparency maps with Photoshop 5.0, I would be happy for any suggestions. I`m doing some graphics for a 2d arcade game and have been having problems creating the alpha maps for smoke, explosions and so on. How can I work on the transparency channel or how can I set the transparency value of all pixels of a layer to 100% once I have extracted the alpha channel (in order to get the base texture in something that is bmp-convertable)? This has proven extremely troublesome because I need both the alpha map and the original, but once I add transparency the original goes bye-bye. I would be very greatful if anyone could give me some tips The same topic was also covered by Bunnz (about a week ago) but I´d be glad if anyone could offer alternatives to the Photoshop. THanx Hase Edited by - Hase on 5/4/00 3:59:17 AM
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There's two ways to do it, and it realy depends on the application and the preference of the programmer. One way is to define a color that will always be transparent - such as pure cyan or magenta - that will never be needed in the colors of the sprite. This is how transparency was defined in DOOM and other sprite-based games.

The second method is a bit more cumbersome to some people. What you do is create two maps: one which is the sprite, and the other which is a pure black/white version, black being trasparent, white being solid.

Hope this helps!

-Nick Robalik
http://www.digital-soapbox.com

Edited by - digisoap on May 7, 2000 12:18:24 AM
-Nick "digisoap" RobalikWeb & Print Design, 2D & 3D Illustration and Animation, Game Designhttp://www.digital-soapbox.com[email=nick@digital-soapbox.com]nick@digital-soabox.com[/email]
Thanks, but i was looking for a way to work on both layers (or files) at the same time so i could modify both and see the results right away. If I modify the greyscale transparency map or the sprite i´d have to put it all into the game to see how it looks, and that takes time. You wouldn´t by any chance know a program that can do that?
I would have sworn that photoshop let you work with an alpha mask on an image with transparency. But gimp does for sure. (www.gimp.org) The xcf format can keep the alpha information separate without losing information. You''ll probably need to export the separate layers into different files though. (xcf isn''t anywhere close to nice to be used in game programming.)

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