There's a new option in version v3.03 (out now on the usual beta page). It's under Options->Preferences->General->Use texture (DXT1) compression.
* TopoFusion displays maps the way I've wanted it to since first writing it -- FAST. The difference in loading map tiles from disk is quite large. I'm getting load times that are about twice as fast.
* Memory usage. TF is a bit of a memory hog if you have the tile cache set high. Not anymore. For the same size of cache (in terms of number of tiles cached) the memory usage is greatly reduced -- cut at least in half.
* Disk usage is a bit higher. Tiles are stored in MapsX.dat files in DXT1 format, not JPEG. The result is about 20% more disk usage. This personally doesn't bother me, because disk space is cheap these days. If I can find a better DXT1 encoder I should be able to reduce this to roughly the same space requirements in a future version.
* Loading previously downloaded JPEG tiles into a compressed (DXT1) graphics system is slower. Basically this means your existing downloaded tiles will load about twice as slow as before. Any newly downloaded tiles will be ripping fast, but old ones will be slower than before.
Texture compression defaults to "ON" (checked). So, some of you may want to disable it if you have a large map files.
Edit - For users upgrading to v3.05 or later (the full release), the DXT1 option will default to "OFF". Only brand new, fresh installs will default to "ON." Regardless, you can always toggle it on / off later.
If there is enough interest, I will write a routine to convert map files downloaded before texture compression. I'm OK with starting from scratch in order to get the speed/memory benefits, but others may have large map collections worth hanging on to.
Map files can be intermixed with DXT1 and JPEG tiles. If the DXT1 option is checked when you download a map tile it will be saved in DXT1. Otherwise it is saved as a JPEG, just as before.
v3.03 and up is able to handle both image types in the same map file. There's just the difference in speed when converting JPEG to DXT1. It will work perfectly fine, as before, if you turn texture compression off and stick with your existing map file.
I'm curious to hear any opinions on this. Try it with a fresh map file (just change your map directory to an empty dir), and let me know what you think. Clearly, for any new users, using DXT1 is the best choice.
Other changes in v3.03:
3.03 - [3/26/07-3/28/07]
Contrast/Brightness are back, not affecting entire display
Fixed crash when coming back from suspend/hibernate
Fixed memory leak on Topo 2/8/32 meter tilesets
Added "Use compressed DXT1 maps" to Options->Preferences
---> See forum for details
Fixed problems with animated sprites
Increased maximum download threads to 50
Fixed crash loading 2/8/32 tilesets in DXT1 mode
GIS layers now has "..." button for choosing files