Software by Tim Green I'm Tim. I make software.

Text, coming soon!

I am currently in the process of adding in some text rendering support. XNA comes with some basic support, but it requires me to know ahead of time exactly what fonts and sizes I want, and if I change my mind I need to go in and edit a data file, rebuild, and try again. Also, it seems to be less-than-optimal as far as performance goes (seems to draw each character as a separate draw call and such).

So, I am using the FreeType library to generate fonts at runtime! Had to write a small wrapper around it so I can use it from my C# code, but it's pretty sweet. Each time I request a character for a given font in a given size, a cache is checked to see if that character has already been used. If it has, then no further work needs to be done. If it's not in the cache, then FreeType will render the character into a memory buffer, and then the character is packed into a giant texture containing all cached characters. While it could probably be better, the packing is pretty tight (it's not just based on a fixed size grid) and works plenty well for right now.

I don't have text rendering happening yet, but I did run a test on the cache to see how the packed textures are working. To the left you can see the results. This is every typeable character on my keyboard, in 4 font faces (2 fonts, with one of them having regular/bold/italic styles), sizes 12/15/18/21/24/27/30/33. The order the characters were added is as follows:

• Each font was processed in a fixed order;
• For each font, the various sizes were processed in order;
• For each size, the characters were added in a shuffled order.

I haven't done much testing with different cache orders, but I suspect it may be improved by doing larger fonts first. However, my intention is to just add characters as they are needed, rather than taking a big chunk of time up front populating with characters that may or may not be needed. When building this texture, the rectangles of each character is recorded so that drawing a string of text is as simple as drawing a series of quads, making direct lookups in the font texture. If needed, I may extend the system to allow multiple textures if it fills up. Or, I may allow it to remove characters that have not been used for a while. But, unless I find myself running out of space, it should be fine as-is.

I am planning to allow custom effects to be used when drawing text, with hooks for using more textures and such. This should make for a pretty powerful text rendering system.

If the texture packing system works out well, I am also considering using it (or something like it) to make my sprites a little more manageable. Instead of loading every frame of every animation for every type of sprite into video memory all at once (which is a lot, even using DXT compression), I would keep all that in system memory and then pack just frames I need to draw the scene into one or more (most likely more) dynamic textures. Basically, it would work similar to Virtual Texturing/Mega Textures, except likely simpler. Of course, that depends on how quickly I can copy data into a texture, since it will be happening quite frequently.