calculates the union bounds of all the collision shapes in the scene

------------------------------------------------------------------------------------------------ Row-by-row memcpy

update the frame, returns a matrix representing the delta transform that can be applied to particles to teleport them to the frame's new location

outer product of a and b, b is considered a row vector

finds the closest particle to a view ray

Poisson sample the volume of a sphere with given separation

creates mesh interior and surface sample points and clusters them into particles

return normal of signed distance field

return normal of signed distance field

send any changes to flex (all buffers guaranteed to be unmapped here)

assumes yaw on y, then pitch on z, then roll on x

uniformly sample volume of a sphere using dart throwing