vector sample_direction_cone(vector center, float maxangle, vector2 u)
Direction in the center of the cone. This does not need to be normalized.
Maximum angle, in radians, away from
center that any sample of the cone
will be, so long as all
u values are between 0 and 1.
Pair of numbers between 0 and 1.
Returns a unit vector, i.e. a vector of length 1, based on
Given uniform random
u pairs of values in [0,1), the returned unit vectors will be
uniform random and continuous with respect to
u on the surface of the unit sphere,
in the area within
maxangle of the direction indicated by