ref: fe1eb39db7ae6904924f3ab1f6f9b34416f2eb1b
dir: /sys/src/libmemdraw/fillpoly.c/
#include <u.h>
#include <libc.h>
#include <draw.h>
#include <memdraw.h>
#include <memlayer.h>
typedef struct Seg Seg;
struct Seg
{
Point p0;
Point p1;
long num;
long den;
long dz;
long dzrem;
long z;
long zerr;
long d;
};
static void zsort(Seg **seg, Seg **ep);
static int ycompare(void*, void*);
static int xcompare(void*, void*);
static int zcompare(void*, void*);
static void xscan(Memimage *dst, Seg **seg, Seg *segtab, int nseg, int wind, Memimage *src, Point sp, int, int, int, int);
static void yscan(Memimage *dst, Seg **seg, Seg *segtab, int nseg, int wind, Memimage *src, Point sp, int, int);
static void
fillline(Memimage *dst, int left, int right, int y, Memimage *src, Point p, int op)
{
Rectangle r;
r.min.x = left;
r.min.y = y;
r.max.x = right;
r.max.y = y+1;
p.x += left;
p.y += y;
memdraw(dst, r, src, p, memopaque, p, op);
}
static void
fillpoint(Memimage *dst, int x, int y, Memimage *src, Point p, int op)
{
Rectangle r;
r.min.x = x;
r.min.y = y;
r.max.x = x+1;
r.max.y = y+1;
p.x += x;
p.y += y;
memdraw(dst, r, src, p, memopaque, p, op);
}
void
memfillpoly(Memimage *dst, Point *vert, int nvert, int w, Memimage *src, Point sp, int op)
{
_memfillpolysc(dst, vert, nvert, w, src, sp, 0, 0, 0, op);
}
void
_memfillpolysc(Memimage *dst, Point *vert, int nvert, int w, Memimage *src, Point sp, int detail, int fixshift, int clipped, int op)
{
Seg **seg, *segtab;
Point p0;
int i;
if(nvert <= 0)
return;
seg = malloc((nvert+2)*sizeof(Seg*));
if(seg == nil)
return;
segtab = malloc((nvert+1)*sizeof(Seg));
if(segtab == nil) {
free(seg);
return;
}
sp.x = (sp.x - vert[0].x) >> fixshift;
sp.y = (sp.y - vert[0].y) >> fixshift;
p0 = vert[nvert-1];
if(!fixshift) {
p0.x <<= 1;
p0.y <<= 1;
}
for(i = 0; i < nvert; i++) {
segtab[i].p0 = p0;
p0 = vert[i];
if(!fixshift) {
p0.x <<= 1;
p0.y <<= 1;
}
segtab[i].p1 = p0;
segtab[i].d = 1;
}
if(!fixshift)
fixshift = 1;
xscan(dst, seg, segtab, nvert, w, src, sp, detail, fixshift, clipped, op);
if(detail)
yscan(dst, seg, segtab, nvert, w, src, sp, fixshift, op);
free(seg);
free(segtab);
}
static long
mod(long x, long y)
{
long z;
z = x%y;
if((long)(((ulong)z)^((ulong)y)) > 0 || z == 0)
return z;
return z + y;
}
static long
sdiv(long x, long y)
{
if((long)(((ulong)x)^((ulong)y)) >= 0 || x == 0)
return x/y;
return (x+((y>>30)|1))/y-1;
}
static long
smuldivmod(long x, long y, long z, long *mod)
{
vlong vx;
if(x == 0 || y == 0){
*mod = 0;
return 0;
}
vx = x;
vx *= y;
*mod = vx % z;
if(*mod < 0)
*mod += z; /* z is always >0 */
if((vx < 0) == (z < 0))
return vx/z;
return -((-vx)/z);
}
static void
xscan(Memimage *dst, Seg **seg, Seg *segtab, int nseg, int wind, Memimage *src, Point sp, int detail, int fixshift, int clipped, int op)
{
long y, maxy, x, x2, xerr, xden, onehalf;
Seg **ep, **next, **p, **q, *s;
long n, i, iy, cnt, ix, ix2, minx, maxx;
Point pt;
USED(clipped);
for(i=0, s=segtab, p=seg; i<nseg; i++, s++) {
*p = s;
if(s->p0.y == s->p1.y)
continue;
if(s->p0.y > s->p1.y) {
pt = s->p0;
s->p0 = s->p1;
s->p1 = pt;
s->d = -s->d;
}
s->num = s->p1.x - s->p0.x;
s->den = s->p1.y - s->p0.y;
s->dz = sdiv(s->num, s->den) << fixshift;
s->dzrem = mod(s->num, s->den) << fixshift;
s->dz += sdiv(s->dzrem, s->den);
s->dzrem = mod(s->dzrem, s->den);
p++;
}
n = p-seg;
if(n == 0)
return;
*p = 0;
qsort(seg, p-seg , sizeof(Seg*), ycompare);
onehalf = 0;
if(fixshift)
onehalf = 1 << (fixshift-1);
minx = dst->clipr.min.x;
maxx = dst->clipr.max.x;
y = seg[0]->p0.y;
if(y < (dst->clipr.min.y << fixshift))
y = dst->clipr.min.y << fixshift;
iy = (y + onehalf) >> fixshift;
y = (iy << fixshift) + onehalf;
maxy = dst->clipr.max.y << fixshift;
ep = next = seg;
while(y<maxy) {
for(q = p = seg; p < ep; p++) {
s = *p;
if(s->p1.y < y)
continue;
s->z += s->dz;
s->zerr += s->dzrem;
if(s->zerr >= s->den) {
s->z++;
s->zerr -= s->den;
if(s->zerr < 0 || s->zerr >= s->den)
print("bad ratzerr1: %ld den %ld dzrem %ld\n", s->zerr, s->den, s->dzrem);
}
*q++ = s;
}
for(p = next; *p; p++) {
s = *p;
if(s->p0.y >= y)
break;
if(s->p1.y < y)
continue;
s->z = s->p0.x;
s->z += smuldivmod(y - s->p0.y, s->num, s->den, &s->zerr);
if(s->zerr < 0 || s->zerr >= s->den)
print("bad ratzerr2: %ld den %ld ratdzrem %ld\n", s->zerr, s->den, s->dzrem);
*q++ = s;
}
ep = q;
next = p;
if(ep == seg) {
if(*next == 0)
break;
iy = (next[0]->p0.y + onehalf) >> fixshift;
y = (iy << fixshift) + onehalf;
continue;
}
zsort(seg, ep);
for(p = seg; p < ep; p++) {
cnt = 0;
x = p[0]->z;
xerr = p[0]->zerr;
xden = p[0]->den;
ix = (x + onehalf) >> fixshift;
if(ix >= maxx)
break;
if(ix < minx)
ix = minx;
cnt += p[0]->d;
p++;
for(;;) {
if(p == ep) {
print("xscan: fill to infinity");
return;
}
cnt += p[0]->d;
if((cnt&wind) == 0)
break;
p++;
}
x2 = p[0]->z;
ix2 = (x2 + onehalf) >> fixshift;
if(ix2 <= minx)
continue;
if(ix2 > maxx)
ix2 = maxx;
if(ix == ix2 && detail) {
if(xerr*p[0]->den + p[0]->zerr*xden > p[0]->den*xden)
x++;
ix = (x + x2) >> (fixshift+1);
ix2 = ix+1;
}
fillline(dst, ix, ix2, iy, src, sp, op);
}
y += (1<<fixshift);
iy++;
}
}
static void
yscan(Memimage *dst, Seg **seg, Seg *segtab, int nseg, int wind, Memimage *src, Point sp, int fixshift, int op)
{
long x, maxx, y, y2, yerr, yden, onehalf;
Seg **ep, **next, **p, **q, *s;
int n, i, ix, cnt, iy, iy2, miny, maxy;
Point pt;
for(i=0, s=segtab, p=seg; i<nseg; i++, s++) {
*p = s;
if(s->p0.x == s->p1.x)
continue;
if(s->p0.x > s->p1.x) {
pt = s->p0;
s->p0 = s->p1;
s->p1 = pt;
s->d = -s->d;
}
s->num = s->p1.y - s->p0.y;
s->den = s->p1.x - s->p0.x;
s->dz = sdiv(s->num, s->den) << fixshift;
s->dzrem = mod(s->num, s->den) << fixshift;
s->dz += sdiv(s->dzrem, s->den);
s->dzrem = mod(s->dzrem, s->den);
p++;
}
n = p-seg;
if(n == 0)
return;
*p = 0;
qsort(seg, n , sizeof(Seg*), xcompare);
onehalf = 0;
if(fixshift)
onehalf = 1 << (fixshift-1);
miny = dst->clipr.min.y;
maxy = dst->clipr.max.y;
x = seg[0]->p0.x;
if(x < (dst->clipr.min.x << fixshift))
x = dst->clipr.min.x << fixshift;
ix = (x + onehalf) >> fixshift;
x = (ix << fixshift) + onehalf;
maxx = dst->clipr.max.x << fixshift;
ep = next = seg;
while(x<maxx) {
for(q = p = seg; p < ep; p++) {
s = *p;
if(s->p1.x < x)
continue;
s->z += s->dz;
s->zerr += s->dzrem;
if(s->zerr >= s->den) {
s->z++;
s->zerr -= s->den;
if(s->zerr < 0 || s->zerr >= s->den)
print("bad ratzerr1: %ld den %ld ratdzrem %ld\n", s->zerr, s->den, s->dzrem);
}
*q++ = s;
}
for(p = next; *p; p++) {
s = *p;
if(s->p0.x >= x)
break;
if(s->p1.x < x)
continue;
s->z = s->p0.y;
s->z += smuldivmod(x - s->p0.x, s->num, s->den, &s->zerr);
if(s->zerr < 0 || s->zerr >= s->den)
print("bad ratzerr2: %ld den %ld ratdzrem %ld\n", s->zerr, s->den, s->dzrem);
*q++ = s;
}
ep = q;
next = p;
if(ep == seg) {
if(*next == 0)
break;
ix = (next[0]->p0.x + onehalf) >> fixshift;
x = (ix << fixshift) + onehalf;
continue;
}
zsort(seg, ep);
for(p = seg; p < ep; p++) {
cnt = 0;
y = p[0]->z;
yerr = p[0]->zerr;
yden = p[0]->den;
iy = (y + onehalf) >> fixshift;
if(iy >= maxy)
break;
if(iy < miny)
iy = miny;
cnt += p[0]->d;
p++;
for(;;) {
if(p == ep) {
print("yscan: fill to infinity");
return;
}
cnt += p[0]->d;
if((cnt&wind) == 0)
break;
p++;
}
y2 = p[0]->z;
iy2 = (y2 + onehalf) >> fixshift;
if(iy2 <= miny)
continue;
if(iy2 > maxy)
iy2 = maxy;
if(iy == iy2) {
if(yerr*p[0]->den + p[0]->zerr*yden > p[0]->den*yden)
y++;
iy = (y + y2) >> (fixshift+1);
fillpoint(dst, ix, iy, src, sp, op);
}
}
x += (1<<fixshift);
ix++;
}
}
static void
zsort(Seg **seg, Seg **ep)
{
int done;
Seg **q, **p, *s;
if(ep-seg < 20) {
/* bubble sort by z - they should be almost sorted already */
q = ep;
do {
done = 1;
q--;
for(p = seg; p < q; p++) {
if(p[0]->z > p[1]->z) {
s = p[0];
p[0] = p[1];
p[1] = s;
done = 0;
}
}
} while(!done);
} else {
q = ep-1;
for(p = seg; p < q; p++) {
if(p[0]->z > p[1]->z) {
qsort(seg, ep-seg, sizeof(Seg*), zcompare);
break;
}
}
}
}
static int
ycompare(void *a, void *b)
{
Seg **s0, **s1;
long y0, y1;
s0 = a;
s1 = b;
y0 = (*s0)->p0.y;
y1 = (*s1)->p0.y;
if(y0 < y1)
return -1;
if(y0 == y1)
return 0;
return 1;
}
static int
xcompare(void *a, void *b)
{
Seg **s0, **s1;
long x0, x1;
s0 = a;
s1 = b;
x0 = (*s0)->p0.x;
x1 = (*s1)->p0.x;
if(x0 < x1)
return -1;
if(x0 == x1)
return 0;
return 1;
}
static int
zcompare(void *a, void *b)
{
Seg **s0, **s1;
long z0, z1;
s0 = a;
s1 = b;
z0 = (*s0)->z;
z1 = (*s1)->z;
if(z0 < z1)
return -1;
if(z0 == z1)
return 0;
return 1;
}