[net.math] ray meets sphere

paul@hpfclk.UUCP (12/30/83)

#N:hpfclk:6300003:000:418
hpfclk!paul    Dec 27 10:46:00 1983


Any references/helpful hints to this problem would be greatly 
appreciated - we have a solution but am curious if it is the
best (w.r.t. number of operations).

What is the quickest way to determine if a ray intersets a sphere?
  (the origin of the ray may be inside/outside the sphere)

The solution we have takes 8 additions, 7 multiplies, 1 divide, and
3 compares.

			    Paul Beiser
			
			...hplabs!hpfcla!paul