Multilingual Unicode rendering in opengl

Question

I have to extend an OpenGL-Rendering system to support international characters (especially Hebrew, Arabic and cyrillic).

Development platform is Windows(XP|Vista|7), alas using Embercardero Delphi 2010.

I currently use wglOutLineFont(...) to build my font's display list and glCallLists(length(m_Text), UNSIGNED_SHORT, PWchar(m_Text) ) to render my strings.

While this is feasible for Latin-1 Characters, building the full Unicode character set in advance is pretty time-consuming (about 8.5 minutes on my machine), so I am looking for a more efficient solution. I thought about limiting the range from u+0020 - u+077f (Latin, Greek, Cyrillic, Arabic and Hebrew) to include just the glyphs I need, but that would just be a solution for my current needs, and will become insufficient once other encoding is needed.

On the upside, I do not have to worry about left-to right or right-to left direction as our application can handle this already.

I would expect this to be a well-known problem, so I would like to ask if there is any reference material on this on the web, or if you could share some insight on this?

Edit A clarification: I use a polygonal font representations. Each Font is constructed at unit size (1.0) in advance and scaled appropriately using glScalef(...) before rendering. I did decide against pre-rasterizing since the users might zoom in quite closely (The application is used for CAD), so rastering artifacts would become visible.

Additionally, since a scene seldom exceeds more then a few hundred characters (mainly labels and measurements), the speed gain from pre-rasterization is negligible.

Answer 1

Don't pre-build the display lists :- create an intermediate sprite that builds the lists on demand, and caches them. Trying to pre-compute lists - or pre generate rasterized textures at every font size, font face, and for all characters, is impractical, Especially when you scale to far eastern character sets.