Best way to morph between waveforms I am making an low-frequency oscillator (LFO) that should be able to output different kinds of waveforms. 
If I, say, want to be able to create a smooth transition from a sine wave to a square wave, what would the best approach be? 
I have thought about creating several hardcoded lookup-tables and "scroll" between these, but I am worried about the transition not being smooth enough, unless there are many of these tables.

If anyone knows about the best way/usual way to solve this problem, I would be happy to hear about it.
this is what we sometimes call "Vector Synthesis" and other times call "Wavetable Synthesis".  linear crossfading between equal-sized circular lookup tables usually suffices.

but make sure the waveforms are aligned.  you can circularly delay (or "rotate") one lookup table relative to the other.  choose a relative rotation so that the cross-correlation between the two waveforms is maximum.  if you somehow crossfade between a sine wave and a square wave where the fundamental of the square wave is outa phase with the sine, you'll get a glitch in the crossfade.