I'll try to answer the questions and explain the correlations.
FIFE is a 2.5d engine and currently there is no support for 3d, sorting works mainly with layers. Maybe we will add support for 3d Models in the future, simply to reduce the amount of needed frames for animations. In the good old days the most engines had only 8bit for RGB(A), that means only 255 colors in combination with a color palette. A good example is Fallout 1 and 2 from Black Isle.
But FIFE have support for 16 and 32bit so the color space is much larger. The drawback is that it needs more Video Ram for the same amount of graphics. Little example: A texture with a 1024*1024 size needs 4MB with 32bit depth but only 1MB with 8bit. FIFE will not limit you but your hardware will
So you should thinking about the amount of animations you need and about the frame count and size. Lets say you use a hexagonal grid, you have one animation set for a char that should have 8 actions (stand, walk, run, shoot,...) and each action consists of 30 frames, each with a size of 200px*200px.
200px * 200px * 32bit / 8 = 160000 byte
160000 byte * 30 frames * 8 action * 6 directions (hexgrid) = 230400000 Byte ~ 219,73 MB
As you see that's a lot. In case you would have 10 different fully featured sets than it would eats up 2,2GB. There are some tricks (like ColorOverlay
) but at the end you must limit the amount.
The difference between SDL and OpenGL is that OpenGL have hardware support, so it should be much faster. In case of FIFE the SDL backend is more a fallback in case the platform has no OpenGL support.
It should be no problem to have multiple battle idle animations. You have different options to speed up things. Like your ground titles should be quite large and you should try to combine textures, that belong together, in a texture atlas. Another point is the size of the viewport, if you want to see the whole map at once the rendering is slower.
You can take a look at fife/tests/fife_test, start the run.py press F10 and write in the console: start benchmarktest
In the example are 1000 skels with an idle animation. You could change the amount to 10000 or more and check the FPS.