Text rendering in OpenGL

[Anton]

Thank you for the replies!

I might consider using bitmp fonts for beginning. I don't have yet experience with that, but as far as I image, I should render a character map (atlas) at runtime, using the OS's built in text rendering functions. The character map would be a single channel texture (alpha map). Then each quad's tex-coordinates should map an exact character from the texture. Then I can combine the character alpha map with a custom texture or color to fill the character in the fragment shader. Would that work? How do you do it in your implementations?

But wouldn't be a problem for the mipmapping if I use a single texture for font atlas? Is it a better solution to store each character in different texture?

About the 3d text geometry, since I target for multiplatform code, I am unable to use the windows api for text geometry. My only idea for now is to find and download a 3d font model set (I guess there should be any) or try to create in Blender, so I can load it from it's file and have each character as a tri model group and then use them to render the text.

[code_glitch]

If you're looking for 2d fonts, I would personally have to point out that ZenGL (by Andru) renders some quite pretty fonts. Basically, you feed it a font from your system (via ttf or whatever you prefer) and give it the characters you want. From this, it generate .zfi file which stores the information for how to render the font, and some .tga images which contain the visual information. Then all you need do is simply combine the two which in hindsight is reasonably easy to do. If you want a reference implementation, one can see some code for it here: https://sourceforge.net/p/prometheus...ee/PM_Font.pas

[Carver413]

I would suggest FreeType it is a portable font engine that would allow to use most fonts. I use it to create bitmap fonts but with some work I think you could pull the information you need to do full 3D. http://sourceforge.net/projects/freetype/

[User137]

I don't have yet experience with that, but as far as I image, I should render a character map (atlas) at runtime, using the OS's built in text rendering functions. The character map would be a single channel texture (alpha map). Then each quad's tex-coordinates should map an exact character from the texture. Then I can combine the character alpha map with a custom texture or color to fill the character in the fragment shader. Would that work? How do you do it in your implementations?

No. You can pre-generate a texture, and save the character pixel widths in file. Texture is usually a 24-bit RGBA image. You can even pre-generate one and then add effects in photoshop/gimp.

But wouldn't be a problem for the mipmapping if I use a single texture for font atlas? Is it a better solution to store each character in different texture?

Mipmapping is done per texture basis, fonts shouldn't need any. Mipmapping technique is used to smoothen repeating textures like terrain that fade into distance. Font neither repeats nor has varying depth. And true, you don't want to include fonts in global single texture. You can't mipmap a texture atlas either, it will simply mess up clamping.