; Constant-power pan.
; x location ranges from hard left = -1 through center = 0 to hard right =
1.
; Angle of pan ranges from hard left = - pi / 2 through center = 0 to hard
right = pi / 2.
ix   = p7
iangle  = ix * 3.14159265359 / 2.0
ileftpan = sqrt(2.0) / 2.0 * (cos(iangle) + sin(iangle))