hi, there are a couple of problems with the example.
first, the double quotes are converted from ", to the slanted version “. try to replace them with ", otherwise scheme will interpret these quoted expressions like “vel” as a variable instead of the string "vel".
second, the colours are set to 0 opacity here:
(pdata-map! ; init the colours
(lambda (c)
(vector (flxrnd) (flxrnd) 1 0))
"c"))
remove the 0 from the end, or replace it with 1. best, gabor
