void
pl_collcontext_insert_object(pl_collisioncontext_t *ctxt, pl_recgrid_t *grid, pl_object_t *obj)
{
int octant = getoctant(&grid->centre, obj);
if (grid->children[octant] && fits(grid->children[octant], obj)){
pl_collcontext_insert_object(ctxt, grid->children[octant], obj);
} else {
obj_array_push(&grid->objs, obj);
}
if (grid->objs.length > THRESHOLD) {
split(ctxt, grid);
}
}
void
plInsertObject(PLcollisioncontext *ctxt, PLrecgrid *grid, PLobject *obj)
{
int octant = getoctant(&grid->centre, obj);
if (grid->children[octant] && fits(grid->children[octant], obj)){
plInsertObject(ctxt, grid->children[octant], obj);
} else {
obj_array_push(&grid->objs, obj);
}
if (grid->objs.length > THRESHOLD) {
split(ctxt, grid);
}
}
static void
split(pl_collisioncontext_t *ctxt, pl_recgrid_t *grid)
{
if (grid->children[0] == NULL) {
for (int i = 0 ; i < 8 ; i++) {
grid->children[i] = pl_new_recgrid(ctxt, grid->size/2.0);
grid->children[i]->centre = grid->centre;
}
lwc_translate3f(&grid->children[0]->centre,
grid->size/4.0, grid->size/4.0, grid->size/4.0);
lwc_translate3f(&grid->children[1]->centre,
grid->size/4.0, grid->size/4.0, -grid->size/4.0);
lwc_translate3f(&grid->children[2]->centre,
grid->size/4.0, -grid->size/4.0, grid->size/4.0);
lwc_translate3f(&grid->children[3]->centre,
grid->size/4.0, -grid->size/4.0, -grid->size/4.0);
lwc_translate3f(&grid->children[4]->centre,
-grid->size/4.0, grid->size/4.0, grid->size/4.0);
lwc_translate3f(&grid->children[5]->centre,
-grid->size/4.0, grid->size/4.0, -grid->size/4.0);
lwc_translate3f(&grid->children[6]->centre,
-grid->size/4.0, -grid->size/4.0, grid->size/4.0);
lwc_translate3f(&grid->children[7]->centre,
-grid->size/4.0, -grid->size/4.0, -grid->size/4.0);
}
for (int i = 0 ; i < grid->objs.length ; i++) {
pl_object_t *obj = grid->objs.elems[i];
int octant = getoctant(&grid->centre, obj);
if (fits(grid->children[octant], obj)) {
pl_collcontext_insert_object(ctxt, grid->children[octant], obj);
obj_array_remove(&grid->objs, i);
i --;
}
}
}
static void
split(PLcollisioncontext *ctxt, PLrecgrid *grid)
{
if (grid->children[0] == NULL) {
for (int i = 0 ; i < 8 ; i++) {
grid->children[i] = plNewRecgrid(ctxt, grid->size/2.0);
grid->children[i]->centre = grid->centre;
}
ooLwcTranslate3f(&grid->children[0]->centre,
grid->size/4.0, grid->size/4.0, grid->size/4.0);
ooLwcTranslate3f(&grid->children[1]->centre,
grid->size/4.0, grid->size/4.0, -grid->size/4.0);
ooLwcTranslate3f(&grid->children[2]->centre,
grid->size/4.0, -grid->size/4.0, grid->size/4.0);
ooLwcTranslate3f(&grid->children[3]->centre,
grid->size/4.0, -grid->size/4.0, -grid->size/4.0);
ooLwcTranslate3f(&grid->children[4]->centre,
-grid->size/4.0, grid->size/4.0, grid->size/4.0);
ooLwcTranslate3f(&grid->children[5]->centre,
-grid->size/4.0, grid->size/4.0, -grid->size/4.0);
ooLwcTranslate3f(&grid->children[6]->centre,
-grid->size/4.0, -grid->size/4.0, grid->size/4.0);
ooLwcTranslate3f(&grid->children[7]->centre,
-grid->size/4.0, -grid->size/4.0, -grid->size/4.0);
}
for (int i = 0 ; i < grid->objs.length ; i++) {
PLobject *obj = grid->objs.elems[i];
int octant = getoctant(&grid->centre, obj);
if (fits(grid->children[octant], obj)) {
plInsertObject(ctxt, grid->children[octant], obj);
obj_array_remove(&grid->objs, i);
i --;
}
}
}
/* ================================================= */
void lconiclist(ellipse *ell, int32_t rs, int32_t cs, int32_t xs, int32_t ys, int32_t xe, int32_t ye,
int32_t A, int32_t B, int32_t C, int32_t D, int32_t E, int32_t F, int32_t xoffset, int32_t yoffset)
/* ================================================= */
{
int32_t octant;
int32_t dxS, dyS, dxD, dyD;
int32_t d,u,v;
int32_t k1sign, k1, Bsign, k2, k3;
int32_t gxe, gye, gx, gy;
int32_t octantcount;
int32_t x, y;
int32_t tmp, tmpdk;
A *= 4;
B *= 4;
C *= 4;
D *= 4;
E *= 4;
F *= 4;
if (DEBUG) fprintf(stderr,"lconic -- %d %d %d %d %d %d\n", xs, ys, xe, ye, xoffset, yoffset);
if (DEBUG) fprintf(stderr,"lconic -- %d %d %d %d %d %d\n", A,B,C,D,E,F);
/* Translate start point to origin... */
/*
F = A*xs*xs + B*xs*ys + C*ys*ys + D*xs + E*ys + F;
D = D + 2 * A * xs + B * ys;
E = E + B * xs + 2 * C * ys;
*/
/* Work out starting octant */
octant = getoctant(D,E);
dxS = SIDEx[octant];
dyS = SIDEy[octant];
dxD = DIAGx[octant];
dyD = DIAGy[octant];
switch (octant) {
case 1:
d = A + B/2 + C/4 + D + E/2 + F;
u = A + B/2 + D;
v = u + E;
break;
case 2:
d = A/4 + B/2 + C + D/2 + E + F;
u = B/2 + C + E;
v = u + D;
break;
case 3:
d = A/4 - B/2 + C - D/2 + E + F;
u = -B/2 + C + E;
v = u - D;
break;
case 4:
d = A - B/2 + C/4 - D + E/2 + F;
u = A - B/2 - D;
v = u + E;
break;
case 5:
d = A + B/2 + C/4 - D - E/2 + F;
u = A + B/2 - D;
v = u - E;
break;
case 6:
d = A/4 + B/2 + C - D/2 - E + F;
u = B/2 + C - E;
v = u - D;
break;
case 7:
d = A/4 - B/2 + C + D/2 - E + F;
u = -B/2 + C - E;
v = u + D;
break;
case 8:
d = A - B/2 + C/4 + D - E/2 + F;
u = A - B/2 + D;
v = u - E;
break;
default:
fprintf(stderr,"FUNNY OCTANT\n");
abort();
}
k1sign = dyS*dyD;
k1 = 2 * (A + k1sign * (C - A));
Bsign = dxD*dyD;
k2 = k1 + Bsign * B;
k3 = 2 * (A + C + Bsign * B);
/* Work out gradient at endpoint */
gxe = xe - xs;
gye = ye - ys;
gx = 2*A*gxe + B*gye + D;
gy = B*gxe + 2*C*gye + E;
octantcount = getoctant(gx,gy) - octant;
if (octantcount < 0)
octantcount = octantcount + 8;
else if (octantcount==0)
if((xs>xe && dxD>0) || (ys>ye && dyD>0) ||
(xs<xe && dxD<0) || (ys<ye && dyD<0))
octantcount +=8;
if (DEBUG)
fprintf(stderr,"octantcount = %d\n", octantcount);
x = xs;
y = ys;
while (octantcount > 0) {
if (DEBUG)
fprintf(stderr,"-- %d -------------------------\n", octant);
if (mcodd(octant)) {
while (2*v <= k2) {
/* Plot this point */
plotlist(ell, rs, cs, x+xoffset, y+yoffset);
/* Are we inside or outside? */
if (DEBUG) fprintf(stderr,"x = %3d y = %3d d = %4d\n", x,y,d);
if (d < 0) { /* Inside */
x = x + dxS;
y = y + dyS;
u = u + k1;
v = v + k2;
d = d + u;
}
else { /* outside */
x = x + dxD;
y = y + dyD;
u = u + k2;
v = v + k3;
d = d + v;
}
}
d = d - u + v/2 - k2/2 + 3*k3/8;
/* error (^) in Foley and van Dam p 959, "2nd ed, revised 5th printing" */
u = -u + v - k2/2 + k3/2;
v = v - k2 + k3/2;
k1 = k1 - 2*k2 + k3;
k2 = k3 - k2;
tmp = dxS; dxS = -dyS; dyS = tmp;
}
else { /* Octant is even */
while (2*u < k2) {
/* Plot this point */
plotlist(ell, rs, cs, x+xoffset, y+yoffset);
if (DEBUG) fprintf(stderr,"x = %3d y = %3d d = %4d\n", x,y,d);
/* Are we inside or outside? */
if (d > 0) { /* Outside */
x = x + dxS;
y = y + dyS;
u = u + k1;
v = v + k2;
d = d + u;
}
else { /* Inside */
x = x + dxD;
y = y + dyD;
u = u + k2;
v = v + k3;
d = d + v;
}
}
tmpdk = k1 - k2;
d = d + u - v + tmpdk;
v = 2*u - v + tmpdk;
u = u + tmpdk;
k3 = k3 + 4*tmpdk;
k2 = k1 + tmpdk;
tmp = dxD; dxD = -dyD; dyD = tmp;
}
octant = (octant&7)+1;
octantcount--;
}
/* Draw final octant until we reach the endpoint */
if (DEBUG)
fprintf(stderr,"-- %d (final) -----------------\n", octant);
if (mcodd(octant)) {
while (2*v <= k2) {
/* Plot this point */
plotlist(ell, rs, cs, x+xoffset, y+yoffset);
if (x == xe && y == ye)
break;
if (DEBUG) fprintf(stderr,"x = %3d y = %3d d = %4d\n", x,y,d);
/* Are we inside or outside? */
if (d < 0) { /* Inside */
x = x + dxS;
y = y + dyS;
u = u + k1;
v = v + k2;
d = d + u;
}
else { /* outside */
x = x + dxD;
y = y + dyD;
u = u + k2;
v = v + k3;
d = d + v;
}
}
}
else { /* Octant is even */
while ((2*u < k2)) {
/* Plot this point */
plotlist(ell, rs, cs, x+xoffset, y+yoffset);
if (x == xe && y == ye)
break;
if (DEBUG) fprintf(stderr,"x = %3d y = %3d d = %4d\n", x,y,d);
/* Are we inside or outside? */
if (d > 0) { /* Outside */
x = x + dxS;
y = y + dyS;
u = u + k1;
v = v + k2;
d = d + u;
}
else { /* Inside */
x = x + dxD;
y = y + dyD;
u = u + k2;
v = v + k3;
d = d + v;
}
}
}
} /* lconiclist() */
