Question

I’m trying to randomly and uniformly generate points on a cube surface in processing. I’m trying to make an animation so I’d need the x, y and z final position of the points.

Any suggestions? Thanks.

Answer 1

Just combine three uniform random distributions. This method assumes you have a unit cube [0..1]^3. If that is not the case, just scale and offset the points after you generate them.

1. Pick a cube side by getting an integer from [0..6)
2. Pick an x coordinate in that side’s plane
3. Pick an y coordinate in that side’s plane

Here’s some C++-ish pseudocode:

vec3 result;
int s=randomSide(); // returns 0 to 5, uniformly distributed
int c=s%3; // get the axis perpendicular to the side you just picked

result[c]=s>2 ? 1.f : 0.f;
result[(c+1)%3]=random01();
result[(c+2)%3]=random01();

If you have a more general box instead of a cube, you have to bias the side-picking according to the areas of the box sides.