采用3D Bresenham算法在兩點間劃一直線
％ This program is ported to MATLAB from:
％ B.Pendleton. line3d - 3D Bresenham s (a 3D line drawing algorithm)
％ ftp://ftp.isc.org/pub/usenet/comp.sources.unix/volume26/line3d, 1992
％
％ Which is referenced by:
％ Fischer, J., A. del Rio (2004). A Fast Method for Applying Rigid
％ Transformations to Volume Data, WSCG2004 Conference.
％ http://wscg.zcu.cz/wscg2004/Papers_2004_Short/M19.pdf
