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OpenGL black 2d text in OpenGL

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Hey guys and gals! I have been working on this on and off for months and I''m just STUCK! I''m trying to draw 2D text (bitmap fonts) and I can get everything to work, EXCEPT what I want: Black text with transparent background. I have looked at some NeHe tutorials and others. I can get it to work with ANY other color BUT black. I''m trying to use TGA files (with 256 characters on them) and I''ve used a few different TGA loaders and I''ve tried saving them with white text on black background and vice-versa. I''m at wit''s end. Please can someone point out what I''m missing!?!? Thank you! Steven www.2e.org to see what I''m working on: www.stevenshultz.com/impera

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Yes, I think I can. I too have had this problem, and the reason it happens is this: a black value (0, 0, 0) means that the stencil becomes useless. The value (0, 0, 0) can''t be used to mask with, as it''s zero, basically. In your TGA font files, you need to make the characters in the alpha channel, not the RGB channels. Look at the Quake III engine. If you have Quake III, unzip the pk3 files in the baseq3 folder and look at the font ones in Paint or something. Nothing. Blackness. It''s not until you view them with something like Paint Shop Pro (which can read the TGA alpha channel) that you see the font masks.

You need to change your blend func setup too. I''m not 100% sure what you need to do, but I think it''s this: glBlendFunc(GL_SRC_ALPHA, GL_SRC_COLOR). Like I say, I''m not too sure about this (if it doesn''t work, experiment with some different values), but you definitely need to use the alpha channel (which will have your font in it) to "mask" the parts of the quad you want to be transparent, not the RGB values. I''m sure there''s a tutorial out there somewhere on this...

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months? u need to create an alpha channel in your texture + enable alphatesting


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What''s you problem.I spend 5(five)!!! months in trying to understand something so simple like the alpha test.And not i''m happy couse i can render everything,that has a background, without it with a alpha func of GL_NOTEQUAL,0

The pain is coming...this sommer!!!

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I mean... THANK YOU
iNsAn1ty, ZedZeek and Mihail121!

I got it to finally work!

I''ve even messed with Photoshop7, PSP7 and BitmapFont builder to see if I was saving the images incorrectly.

But iNsAn1ty, you were right with the whole 0,0,0 is not a color thing...

btw - this is for an OpenGL Civ2 clone (game). I''m working on an OpenGL UI right now. I''ve got the mouse, buttons, a few other things going... obviously text is important here.

Thank you all again!

you can reach me at:
2e_at_2e.org (damn spambots)

take care guys!

ps - zedzeek, your skills and CV scare me! ha! Good luck mate!

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i have a white font on black background
the darker it is the less it is blended with the destination color 1-0=1

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>>I got it to finally work!

unfortunatly this might give the impression of working but its not correct, u need an alpha channel in your texture. i''ll write up a small explanation tonight (finally) + see if i can get it put into the faq

ps thats my old cv (my new one is MUCH better )


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