Algorithm of computer graphic

On this page I'd like to introduce U main algorithms, are used in computer graphic. I thought, that it will be interesting not only to real professional at this area (they have known it before :)) ), but to every delittante programmer. It's interesting to know what compiler do, when it met, for example,the next line

line(-10,-10,100,100);

By the way, here and forward will allege the programm texts, are written in Pascal. It's the best language for learning programming.

So, the main algorithms :

  1. Raster unfold of segment (Algorithm of Bresenham)

  2. Raster unfold of segment (Algorithm DDA)

  3. Raster unfold of circle (Algorithm of Bresenham)

Another one. Here I am not allege algorithm of clipping. Wait for upgrade my site

Raster unfold of segment (Algorithm of Bresenham)

procedure lineBres(x1,y1, x2, y2 : integer);
var
   x, y, xend, yend, s, dx, dy, d, inc1, inc2 : integer;
begin
   dx := abs(x2-x1); dy := abs(y2-y1);
   if dx > dy then begin {almost horizontal}
      inc1 := 2*dy; inc2 := 2*(dy - dx); d := 2*dy - dx;
      if x1 < x2 then begin
         x := x1; y := y1; xend:= x2;
         if y1 < y2 then s := 1
         else s := -1;
      end
      else begin
         x := x2; y := y2; xend := x1;
         if y1 > y2 then s := 1
         else s := -1;
      end;
      putpixel(x, y, cc); {pixel, color ÑÑ}
      while x < xend do begin
         inc(x);
         if d > 0 then begin
            inc(y,s);
            inc(d, inc2);
         end
         else inc(d, inc1);
         putpixel(x, y, cc);
      end
   end
   else...{the same}           


Raster unfold of segment (Algorithm DDA)

procedure lineBres(x1,y1, x2, y2 : integer);
var
   x, y,xend, yend, dx, dy : integer;
   k, xf, yf : float; {type float - one of float types}
begin
   dx := abs(x2-x1); dy := abs(y2-y1);
   if dx > dy then begin {almost horizontal}
      k := (y2 - y1)/(x2 - x1);
      if x1 < x2 then begin
         yf := y1; x := x1; xend := x2;
      end
      else begin
         x := x2; xend := x1; yf := y2;
      end;
      repeat
         putpixel(x, round(yf),cc){put pixel, color ÑÑ}
         inc(x); inc(yf, k);
      until x > xend;
   end
   else if dy = 0  then putpixel(x1, y1, cc)
   else ... {the same}


Raster unfold of circle(Algorithm of Bresenham)

procedure circle(xc,yc, r : integer);
var
   d, x, y : integer;
begin
   x := 0; y := r; d := 3 - 2*r;
   putpixel8(xc, yc, 0, r); {after one point we can put 7 more}
   while x < y do begin
      if d <= 0 then
         d := d + 4*x + 6
      else begin
         d := d + 4*(x - y) + 10; dec(y);
      end;
      inc(x);
      putpixel8(xc, yc, x, y);
   end;
end;

In preparing this page was used lectures of Ñ.Ç.Ñâåðäëîâà