Thank you both for the replies. 

@docB, very helpful, I appreciate it.

Your video on YouTube of sterrain really intrigued me so I wanted to explore it. Unfortunately, I have only Csound for Android to work with and it supports neither wterrain2 (unstable) nor sterrain (not recognized). And as a slight aside, I can see your linked webpage instr but it doesn't function in any of my browsers.

So I've been trying to see if I could loosely imitate the other opcodes using wterrain. If anyone is curious as to the results so far you can check some out here (my attempt to emulate what I thought was cornoid but now appears to be limacron):
https://github.com/ST-Music/csound-examples/tree/wterrain-opcode

If you can use either of the other 2 opcodes it's likely of no interest. As always, comments, tips or suggestions to a newbie are welcome.

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