[sdiy] complex waveforms

[anthony]

Is there a good resource online for these kinds of things? I did a cursory 
Google, but I don't think I narrowed it down enough. What I'm looking for is 
a sort of half-hypertriangle - both sides (not at the same time but 
selectable). I thought this might be a better waveform for an LFO to 
modulate a BBD VCO for pitch shifting. Log attack, super fast decay or super 
fast attack, log decay. Something tells me it's simpler than I think and I 
am just not getting it. Like an integrator should do it maybe or maybe that 
wouldn't do everything I want...

But thinking about that made me think of other complex waveforms as well. 
Things like trapezoid, half circle. I also found a reference to something 
that Scott Gravenhorst had done with X-OR gates or something, but no 
references. But that was a different thing altogether.