SRL Archive - Development

Right so, this procedure returns a TPA, containing a the points for a nice straight line joining any two TPoints.

As you can see, it is quite mathematical, and therefore slow if you want to update it constantly, to say, draw a line from a constant co-ordinate to the mouses position.

I originally made it to directly manipulate the pixels of bitmaps, but i think it can be added to simba easier this way, to give it a much needed speed boost.

if the name doesnt suit or conflicts feel free to change it.

function PointToPoint(start, finish: TPoint): TPointArray;
var
  steep: boolean;
  deltax, deltay, error, ystep, x1, y1, len: integer;
  TPA: TPointArray;
begin
  steep := (iAbs(finish.Y - start.Y) > iAbs(finish.X - start.X));
    if steep then
      begin
        swap(start.X, start.Y);
        swap(finish.X, finish.Y);
      end;
    if start.X > finish.X then
      begin
        swap(start.X, finish.X);
        swap(start.Y, finish.Y);
      end;
    deltax := (finish.X - start.X);
    deltay := iAbs(finish.Y - start.Y);
    error := (deltax / 2);
    y1 := start.Y
    if (start.Y < finish.Y) then
      ystep := 1
    else
      ystep := -1;
    for x1 := start.X to finish.X do
      begin
        if steep then
        begin
          len := Length(TPA);
          SetArrayLength(TPA, len+1);
          TPA[len] := Point(y1, x1);
        end else
        begin
          len := Length(TPA);
          SetArrayLength(TPA, len+1);
          TPA[len] := Point(x1, y1);
        end;
        error := error - deltay;
        if error < 0 then
          begin
            y1 := y1 + ystep;
            error := error + deltax;
          end;
      end;
  Result := TPA;
end;

~mc_teo

I wrote this to my area recorder which never got completed

function MakeLine(P1, P2: TPoint): TPointArray;
var
  sina, cosa, hypo: extended;
  R, maxR: integer;
begin
  maxR := distance(P1.X, P1.Y, P2.X, P2.Y);
  hypo := hypot(P2.X - P1.X, P2.Y - P1.Y);
  sina := (P2.Y - P1.Y) div hypo;
  cosa := (P2.x - P1.x) div hypo;
  SetLength(Result, maxR + 1);

  for R := 0 to maxR do
    Result[R] := Point(P1.X + Round(cosa*R),
                       P1.Y + Round(sina*R));

  //ClearDoubleTPA(Result);
end;