[sdiy] Random Timbre Synth

[Joel B]

Hi Scott, 

Question about your Spline function:

y = ( x - 1 ) * x * ( x + 1 ) 

How does this get you the points in between known point  x1,y1 and known point x2,y2?   I've been trying to figure out some things like this for both a game I am working on (computing curved attack vectors) and for a simple synthesis program I'm working on (figuring out how to draw & scale smooth waveforms on the screen)

How are you getting from the starting y position to the destination y position, since that formula doesn't seem to take into account either, but just generates a y based on an x value, but you are somehow using this formula to connect two points on the y axis over time (or distance)

 - Joel