| OCR Text |
Show 39 edge the of position current (Xl as represented by At a and Zl) YI is particular plane. (X2 and value a Given the Z2), Y2 (O<a<l) a line, scan coordinates Z the Y=Yscan, the by solving the the on of edge equation: determine can function Y endpoints point any in we two for the X a a(Yscan) and substituting it into X Z(Yscan) Z(a(Yscan)) expressions of edge block when An edge plane scan vertex. edge block which the a is edge is it active counts list. and Z functions initialize to first is removed Y X and Z fields created. the from the the active list of coordinate its when the lowermost usually detected by maintaininq within each to and to it below counter int(Yl)-int(Y2) When be drops This used are must X (a (Yscan) ) X(Yscan) These an the to record remain the zero the of scan This is initialized active. decremented lines number upon edge block each is scan line removed over to update. from the |
