Triangle algorithm

Lars Gollub a écrit dans l’article
<6up816$k8u36@forums.borland.com >…
> >Can you use the fillpoly routine or something like that?
>
> Well, no. This is why I am asking for the algorithm. Windows is
> very slow in drawing *many small* Objects. So I draw them


well, take a look in the good all SWAG ! Von: Paul TOTH
Betreff: Re: Triangle algorithm
Datum: Dienstag, 29. September 1998 08:28

look on my Pascal Page for ZED & BODY.
—
see the triangle as a array of horizontal lines…(or vertical for fast VGA
X-Mode)

0
.
RightX…..LeftX
. A
. BBBB
. CCCCCC
. DDDDDDDD
.
MaxY

[code lang=”delphi”]Var
RightX:array[0..MaxY] of word;
LeftX :array[0..MaxY] of word;

procedure DrawTriangle(color:TColor);
var
x1,x2,y:integer;
begin
for y:=0 to MaxY do begin
x1:=RightX;
x2:=LeftX;
if x1<0 then begin dx:=-dx; ix:=-1 end else ix:=+1; dy:=y2-y1; if dy<0 then begin dy:=-dy; iy:=-1 end else iy:=+1; if dx>dy then begin
e1:= 2*dy;
e2:=e1-dx;
e3:=e2-dx;
for i:=0 to dx do begin
if x1LeftSX[y1] then LeftX[y1] :=x1;
inc(x1,ix);
if e2<0 then inc(e2,e1) else begin inc(e2,e3); inc(y1,iy); end; end; end else begin e1:= 2*dx; e2:=e1-dy; e3:=e2-dy; for i:=0 to dy do begin if x1LeftX[y1] then LeftX[y1] :=x1; inc(y1,iy); if e2<0 then inc(e2,e1) else begin inc(e2,e3); inc(x1,ix); end; end; end; end; procedure Triangle(x1,y1,x2,y2,x3,y3,color:integer); begin fillchar(RightX,SizeOf(RightX),255); // default 65535 fillchar(LeftX,SizeOf(LeftX),0); // default 0 scan(x1,y1,x2,y2); scan(x2,y2,x3,y3); scan(x3,y3,x1,y1); DrawTriangle(Color); end; [/code] [tags]Delphi, Graphic[/tags]