void clipline(dcpt winmin,dcpt winmax,wcpt2 p1,wcpt2 p2)
{
unsigned char encode(wcpt2,dcpt,dcpt);
unsigned char code1,code2;
int done = 0 , draw = 0;
float m;
void swapcode(unsigned char *c1,unsigned char *c2);
void swappts(wcpt2 *p1,wcpt2 *p2);
while(!done)
{
code1 = encode(p1,winmin,winmax);
code2 = encode(p2,winmin,winmax);
if(ACCEPT(code1,code2))
{
draw = 1;
done = 1;
}
else if(REJECT(code1,code2))
done = 1;
else if(INSIDE(code1))
{
swappts(&p1,&p2);
swapcode(&code1,&code2);
}
if(code1 & LEFT_EDGE)
{
p1.y += (winmin.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
p1.x = winmin.x;
}
else if(code1 & RIGHT_EDGE)
{
p1.y += (winmax.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
p1.x = winmax.x;
}
else if(code1 & TOP_EDGE)
{
if(p2.x != p1.x)
p1.x += (winmin.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y);
p1.y = winmin.y;
}
else if(code1 & BOTTOM_EDGE)
{
if(p2.x != p1.x)
p1.x += (winmax.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y);
p1.y = winmax.y;
}
}
if(draw)
{
setcolor(5);
line(p1.x,p1.y,p2.x,p2.y);
}
}
static int
_clipaaline (SDL_Rect *clip, float x1, float _y1, float x2, float y2,
float *outpts)
{
int left = clip->x + 1;
int right = clip->x + clip->w - 2;
int top = clip->y + 1;
int bottom = clip->y + clip->h - 2;
int code1, code2;
int draw = 0;
float swaptmp;
int intswaptmp;
float m; /*slope*/
if (!outpts)
{
SDL_SetError ("outpts argument NULL");
return 0;
}
while (1)
{
code1 = _fencode (x1, _y1, left, top, right, bottom);
code2 = _fencode (x2, y2, left, top, right, bottom);
if (ACCEPT (code1, code2))
{
draw = 1;
break;
}
else if (REJECT (code1, code2))
break;
else
{
if (INSIDE (code1))
{
swaptmp = x2;
x2 = x1;
x1 = swaptmp;
swaptmp = y2;
y2 = _y1;
_y1 = swaptmp;
intswaptmp = code2;
code2 = code1;
code1 = intswaptmp;
}
if (x2 != x1)
m = (y2 - _y1) / (x2 - x1);
else
m = 1.0f;
if (code1 & LEFT_EDGE)
{
_y1 += ((float)left - x1) * m;
x1 = (float)left;
}
else if (code1 & RIGHT_EDGE)
{
_y1 += ((float)right - x1) * m;
x1 = (float)right;
}
else if (code1 & BOTTOM_EDGE)
{
if (x2 != x1)
x1 += ((float)bottom - _y1) / m;
_y1 = (float)bottom;
}
else if (code1 & TOP_EDGE)
{
if(x2 != x1)
x1 += ((float)top - _y1) / m;
_y1 = (float)top;
}
}
}
if (draw)
{
outpts[0] = x1;
outpts[1] = _y1;
outpts[2] = x2;
outpts[3] = y2;
}
return draw;
}