static int
psdist(Point p, Point a, Point b)
{
int num, den;
p = subpt(p, a);
b = subpt(b, a);
num = p.x*b.x + p.y*b.y;
if(num <= 0)
return normsq(p);
den = normsq(b);
if(num >= den)
return normsq(subpt(b, p));
return normsq(subpt(divpt(mulpt(b, num), den), p));
}
static void
_bezsplinepts(Plist *l, Point *pt, int npt)
{
Point *p, *ep;
Point a, b, c, d;
int periodic;
if(npt<3)
return;
ep = &pt[npt-3];
periodic = eqpt(pt[0], ep[2]);
if(periodic){
a = divpt(addpt(ep[1], pt[0]), 2);
b = divpt(addpt(ep[1], mulpt(pt[0], 5)), 6);
c = divpt(addpt(mulpt(pt[0], 5), pt[1]), 6);
d = divpt(addpt(pt[0], pt[1]), 2);
bpts(l, a, b, c, d);
}
for(p=pt; p<=ep; p++){
if(p==pt && !periodic){
a = p[0];
b = divpt(addpt(p[0], mulpt(p[1], 2)), 3);
}
else{
a = divpt(addpt(p[0], p[1]), 2);
b = divpt(addpt(p[0], mulpt(p[1], 5)), 6);
}
if(p==ep && !periodic){
c = divpt(addpt(mulpt(p[1], 2), p[2]), 3);
d = p[2];
}
else{
c = divpt(addpt(mulpt(p[1], 5), p[2]), 6);
d = divpt(addpt(p[1], p[2]), 2);
}
bpts(l, a, b, c, d);
}
appendpt(l, d);
}
/*
* Convert cubic Bezier curve control points to polyline
* vertices. Leaves the last vertex off, so you can continue
* with another curve.
*/
static void
bpts1(Plist *l, Point p0, Point p1, Point p2, Point p3, int scale)
{
Point p01, p12, p23, p012, p123, p0123;
Point tp0, tp1, tp2, tp3;
tp0=divpt(p0, scale);
tp1=divpt(p1, scale);
tp2=divpt(p2, scale);
tp3=divpt(p3, scale);
if(psdist(tp1, tp0, tp3)<=1 && psdist(tp2, tp0, tp3)<=1){
appendpt(l, tp0);
appendpt(l, tp1);
appendpt(l, tp2);
}
else{
/*
* if scale factor is getting too big for comfort,
* rescale now & concede the rounding error
*/
if(scale>(1<<12)){
p0=tp0;
p1=tp1;
p2=tp2;
p3=tp3;
scale=1;
}
p01=addpt(p0, p1);
p12=addpt(p1, p2);
p23=addpt(p2, p3);
p012=addpt(p01, p12);
p123=addpt(p12, p23);
p0123=addpt(p012, p123);
bpts1(l, mulpt(p0, 8), mulpt(p01, 4), mulpt(p012, 2), p0123, scale*8);
bpts1(l, p0123, mulpt(p123, 2), mulpt(p23, 4), mulpt(p3, 8), scale*8);
}
}
/*
* make a "wedge" mask covering the desired angle and contained in
* a surrounding square; draw a full ellipse; intersect that with the
* wedge to make a mask through which to copy src to dst.
*/
void
memarc(Memimage *dst, Point c, int a, int b, int t, Memimage *src, Point sp, int alpha, int phi, int op)
{
int i, w, beta, tmp, c1, c2, m, m1;
Rectangle rect;
Point p, bnd[8];
Memimage *wedge, *figure, *mask;
if(a < 0)
a = -a;
if(b < 0)
b = -b;
w = t;
if(w < 0)
w = 0;
alpha = -alpha; /* compensate for upside-down coords */
phi = -phi;
beta = alpha + phi;
if(phi < 0){
tmp = alpha;
alpha = beta;
beta = tmp;
phi = -phi;
}
if(phi >= 360){
memellipse(dst, c, a, b, t, src, sp, op);
return;
}
while(alpha < 0)
alpha += 360;
while(beta < 0)
beta += 360;
c1 = alpha/90 & 3; /* number of nearest corner */
c2 = beta/90 & 3;
/*
* icossin returns point at radius ICOSSCALE.
* multiplying by m1 moves it outside the ellipse
*/
rect = Rect(-a-w, -b-w, a+w+1, b+w+1);
m = rect.max.x; /* inradius of bounding square */
if(m < rect.max.y)
m = rect.max.y;
m1 = (m+ICOSSCALE-1) >> 10;
m = m1 << 10; /* assure m1*cossin is inside */
i = 0;
bnd[i++] = Pt(0,0);
icossin(alpha, &p.x, &p.y);
bnd[i++] = mulpt(p, m1);
for(;;) {
bnd[i++] = mulpt(corners[c1], m);
if(c1==c2 && phi<180)
break;
c1 = (c1+1) & 3;
phi -= 90;
}
icossin(beta, &p.x, &p.y);
bnd[i++] = mulpt(p, m1);
figure = nil;
mask = nil;
wedge = allocmemimage(rect, GREY1);
if(wedge == nil)
goto Return;
memfillcolor(wedge, DTransparent);
memfillpoly(wedge, bnd, i, ~0, memopaque, p00, S);
figure = allocmemimage(rect, GREY1);
if(figure == nil)
goto Return;
memfillcolor(figure, DTransparent);
memellipse(figure, p00, a, b, t, memopaque, p00, S);
mask = allocmemimage(rect, GREY1);
if(mask == nil)
goto Return;
memfillcolor(mask, DTransparent);
memimagedraw(mask, rect, figure, rect.min, wedge, rect.min, S);
c = subpt(c, dst->r.min);
memdraw(dst, dst->r, src, subpt(sp, c), mask, subpt(p00, c), op);
Return:
freememimage(wedge);
freememimage(figure);
freememimage(mask);
}
