Fw: Algoritmus: usecka, kruznice

[Milan]

----- Original Message ----- 
From: "Milan" <milger@pobox.sk>
To: "HW-news" <hw-list@list.hw.cz>
Sent: Saturday, September 01, 2007 5:13 PM
Subject: Re: Algoritmus: usecka, kruznice


> Dovolim si len tak pre inspiraciu usecku:
>
> DRAW_LINE(unsigned char x1, unsigned char y1,
>    unsigned char x2, unsigned char y2)
> {
> char kvadrant;
> int x,y,dx,dy;
> int plus,minus,pos,steps;
>  dx = (int)x2 - (int)x1;
>  dy = (int)y2 - (int)y1;
>  if (abs(dx)<abs(dy)) kvadrant = 1;     //kvadrant
>  else        kvadrant = 0;
>  if (dx<0) kvadrant = kvadrant + 2;
>  if (dy<0) kvadrant = kvadrant + 4;
>  steps = abs(dx) + abs(dy);       //number steps
>  switch (kvadrant)
>  {
>    case 0:
>      pos = (2*dy-dx);
>      plus = 2*(dy-dx);
>      minus = 2*dy;
>    break;
>    case 1:
>      pos = (2*dx-dy);
>      plus = 2*(dx-dy);
>      minus = 2*dx;
>    break;
>    case 2:
>      pos = (2*dy+dx);
>      plus = 2*(dy+dx);
>      minus = 2*dy;
>    break;
>    case 3:
>      pos = (2*(-dx)-dy);
>      plus = 2*((-dx)-dy);
>      minus = 2*(-dx);
>    break;
>    case 4:
>      pos = (2*(-dy)-dx);
>      plus = 2*((-dy)-dx);
>      minus = 2*(-dy);
>    break;
>    case 5:
>      pos = (2*dx+dy);
>      plus = 2*(dx+dy);
>      minus = 2*dx;
>    break;
>    case 6:
>      pos = (2*(-dy)+dx);
>      plus = 2*((-dy)+dx);
>      minus = 2*(-dy);
>    break;
>    case 7:
>      pos = (2*(-dx)+dy);
>      plus = 2*((-dx)+dy);
>      minus = 2*(-dx);
>    break;
>  }
>  x = x1;
>  y = y1;
>  PUT_PIXEL(x,y);
>  while (steps)           //step at kvadrant
>  {
>    switch (kvadrant)
>    {
>      case 0:
>     if (pos>=0) y++;
>  x++;
>      break;
>      case 1:
>     if (pos>=0) x++;
>  y++;
>      break;
>      case 2:
>     if (pos>=0) y++;
>  x--;
>      break;
>      case 3:
>     if (pos>=0) x--;
>  y++;
>      break;
>      case 4:
>     if (pos>=0) y--;
>  x++;
>      break;
>      case 5:
>     if (pos>=0) x++;
>  y--;
>      break;
>      case 6:
>     if (pos>=0) y--;
>  x--;
>      break;
>      case 7:
>     if (pos>=0) x--;
>  y--;
>      break;
>    }
>    PUT_PIXEL(x,y);          //draw pixel
>    if (pos>=0)           //next step
> {
>   pos = pos+plus;
>   steps--;
> }
>    else
>   pos = pos+minus;
>    steps--;
>  }
> }
>
>
>
> Milan
>
>
> ----- Original Message ----- 
> From: "Va Sm" <SpiritusII@seznam.cz>
> To: <hw-list@list.hw.cz>
> Sent: Saturday, September 01, 2007 12:09 PM
> Subject: Algoritmus: usecka, kruznice
>
>
> Dobry den,
> hledam vhodny(efektivni) algoritmus pro vykresleni usecky (zadano dvema 
> body) a kruznice. Jde mi o implementaci do jednocipu, idelane v C. 
> Poradite?
>
> V. Smidl
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