Category : Files from Magazines
Archive   : N7V11.ZIP
Filename : DOLINE.BAS

SUB DoLine (X1#, Y1#, X2#, Y2#) STATIC

IF ABS(X2# - X1#) < .01 THEN 'calc slope of line
My# = SGN(Y2# - Y1#) 'based on configuration
Mx# = 0 'of the end points
ELSE
M# = (Y2# - Y1#) / (X2# - X1#)
IF ABS(M#) > 1 THEN
My# = SGN(Y2# - Y1#)
Mx# = SGN(X2# - X1#) / ABS(M#)
ELSE
My# = M# * SGN(Y2# - Y1#)
Mx# = SGN(X2# - X1#)
END IF
END IF

DrawPixel:

IF POINT(X1#, Y1#) = 0 THEN PSET(X1#, Y1#) 'plot if black

X1# = X1# + Mx# 'increment current pixel on screen
Y1# = Y1# + My# ' whether or not a point was plotted
IF INT(X1#) = INT(X2#) AND INT(Y1#) = INT(Y2#) THEN _
EXIT SUB 'we reached the end of the line

GOTO DrawPixel 'attempt to draw the next pixel

END SUB