Finds the entry plane of the first octant that a ray travels through.
Determining the first octant requires knowing which of the t0s is the largest. The tms of the other axes must also be
compared against that largest t0.
Parameters
tx0: number
Ray projection parameter.
ty0: number
Ray projection parameter.
tz0: number
Ray projection parameter.
txm: number
Ray projection parameter mean.
tym: number
Ray projection parameter mean.
tzm: number
Ray projection parameter mean.
Returns number
The index of the first octant that the ray travels through.
Finds the entry plane of the first octant that a ray travels through.
Determining the first octant requires knowing which of the t0s is the largest. The tms of the other axes must also be compared against that largest t0.