shn@allgfx.oz.au (Si-Hanh NGUYEN) (02/26/90)
Does anybody know the detailed algorithm used in pr_vector() of Sun Pixrect ? The manual says that "pr_vector draws balanced vectors. (The technique used is to balance the Breshenham error term)". I have to fill some shapes which have straight edge(s) by pr_traprop(), and I would like these edges align perfectly with lines drawn by pr_vector() (or bold lines by pr_polygon_2()). I need to know how pr_vector() works in order to derive the bit vector of chain of those straight edges. I have tried the Bresenham algorithm from Foley an Van Dam. It works except when the line segment is in the 4th and 8th octant (Y-axis is from top to bottom and slope of the line segment is in ]0,-1[). Any help would be greatly appreciated. Si-Hanh Nguyen shn@allgfx.agi.oz