Xiaolin Wu's line algorithm: Difference between revisions

Revision as of 06:50, 16 January 2008

Revision as of 00:29, 1 February 2008

Line 36:

dy = y2 - y1

gradient = dy / dx

if abs(dx) > abs(dy) then

''// handle second"horizontal" endpointlines''

''// handle first endpoint''

xend = round(x1)

yend = y1 + gradient * (xend - x1)

xgap = rfpart(x1 + 0.5)

xpxl1 = xend '' // this will be used in the main loop''

ypxl1 = ipart(yend)

plot(xpxl1, ypxl1, rfpart(yend) * xgap)

plot(xpxl1, ypxl1 + 1, fpart(yend) * xgap)

intery = yend + gradient ''// first y-intersection for the main loop''

''// handle second endpoint''

xend = round(x2)

yend = y2 + gradient * (xend - x2)

xgap = fpart(x2 + 0.5)

xpxl2 = xend '' // this will be used in the main loop''

ypxl2 = ipart(yend)

plot(xpxl2, ypxl2, rfpart(yend) * xgap)

plot(xpxl2, ypxl2 + 1, fpart(yend) * xgap)

''// handle firstmain endpointloop''

'''for''' x '''from''' xpxl1 + 1 '''to''' xpxl2 - 1 '''do'''

xend = round(x1)

plot(x, ipart(intery), rfpart(intery))

yend = y1 + gradient * (xend - x1)

xgap = rfpart(x1 + 0.5)

xpxl1 = xend '' // this will be used in the main loop''

ypxl1 = ipart(yend)

plot(xpxl1, ypxl1, rfpart(yend) * xgap)

plot(xpxl1, ypxl1 + 1, fpart(yend) * xgap)

intery = yend + gradient ''// first y-intersection for the main loop''

''// handle second endpoint''

xend = round(x2)

yend = y2 + gradient * (xend - x2)

xgap = fpart(x2 + 0.5)

xpxl2 = xend '' // this will be used in the main loop''

ypxl2 = ipart(yend)

plot(xpxl2, ypxl2, rfpart(yend) * xgap)

plot(xpxl2, ypxl2 + 1, fpart(yend) * xgap)

''// main loop''

'''for''' x '''from''' xpxl1 + 1 '''to''' xpxl2 - 1 '''do'''

plot(x, ipart(intery), rfpart(intery))

plot(x, ipart(intery) + 1, fpart(intery))

intery = intery + gradient

'''repeat'''

else

''//handle "vertical" lines same code as above but X takes the role of Y

'''end function'''

</code>