Графика (алгоритм Брезенхема)

uses graphABC;
procedure drawLine(x1, y1, x2, y2: integer);
var
  currentX, currentY: integer;
  errorX, errorY: integer;
  d, dx, dy, incX, incY: integer;
begin
  dx := x2 - x1;
  dy := y2 - y1;
  errorX := 0;
  errorY := 0;
 
  if(dx > 0) then incX := 1
    else if(dx = 0) then incX := 0
      else incX := -1;
 
  if(dy > 0) then incY := 1
    else if(dy = 0) then incY := 0
      else incY := -1;
 
  dx := abs(dx);
  dy := abs(dy);
 
  if(dy > dx) then d := dy
    else d := dx;
 
  currentX := x1;
  currentY := y1;
  SetPixel(currentX, currentY, 0);
  while((currentX <> x2) OR (currentY <> y2)) do
  begin
    errorX := errorX + dx;
    errorY := errorY + dy;
    if(errorX >= d) then
    begin
         errorX := errorX - d;
         currentX := currentX + incX;
    end;
    if(errorY >= d) then
    begin
         errorY := errorY - d;
         currentY := currentY + incY;
    end;
    SetPixel(currentX, currentY, 0);
  end;
end;
begin
setpencolor(clBlue);
drawLine(10,50,350,400);
setpencolor(clRed);
line(10,50,350,400)
end.

setpencolor(clGreen);
drawLine(10,50,350,400);

setpencolor(clBlue);
drawLine(10,50,350,400);
setpencolor(clRed);
line(10,50,350,400);
sleep(2000);
clearwindow;
setpencolor(clGreen);
drawLine(10,50,350,400);
setpencolor(clBlack);
line(10,50,350,400);