int cycle()
{
/* find number of contacts/bonds*/
int contacts = NUM_XY_BONDS + NUM_Z_BONDS;
/* touching a wall counts as two contacts*/
if (X == 0 || X == substrate_width)
{
contacts += 2;
}
if (Y == 0 || Y == substrate_width)
{
contacts += 2;
}
if (contacts <= get_max_num_bonds(calcium_level))
{
/* cell comes out of G0*/
CYCLE++;
CONTACT_INHIBITED_TICKS = 0;
}
else
{
/* cell enters G0*/
CONTACT_INHIBITED_TICKS++;
}
/* check to see if enough time has elapsed as to whether cell can divide*/
if (can_divide(TYPE,CYCLE))
{
add_ask_id_message(ID, 1000.0, X, Y, Z);
}
return 0;
}
/* all this is rather expensive :( */
static void tick( State *st )
{
int new_num_cells, num_cells=0;
int b, j;
int x, y, w4=st->width/4, h4=st->height/4, offset;
double min_dist;
int min_index;
int num_living = 0;
const double check_dist = 0.75*st->move_dist;
const double grow_dist = 0.75*st->radius;
const double adult_radius = st->radius;
/* find number of cells capable of division
and count living cells
*/
for (b=0; b<st->num_cells; ++b) {
if (st->cell[b].energy > 0) num_living++;
if (can_divide( st, &st->cell[b] )) num_cells++;
}
new_num_cells = st->num_cells + num_cells;
/* end of simulation ? */
if (0 == num_living || new_num_cells >= st->max_cells) {
if (st->pause_counter > 0) st->pause_counter--;
if (st->pause_counter > 0) return;
create_cells( st );
st->pause_counter = st->pause;
} else if (num_cells) { /* any fertile candidates ? */
for (b=0, j=st->num_cells; b<st->num_cells; ++b) {
if (can_divide( st, &st->cell[b] )) {
st->cell[b].vx = random_interval( -50, 50 ) * 0.01;
st->cell[b].vy = random_interval( -50, 50 ) * 0.01;
st->cell[b].age = random_max( 0x0f );
/* half energy for both plus some bonus for forking */
st->cell[b].energy =
st->cell[b].energy/2 + random_max( 0x0f );
/* forking makes me shrink */
st->cell[b].growth = 0.995;
/* this one initially goes into the oposite direction */
st->cell[j].vx = -st->cell[b].vx;
st->cell[j].vy = -st->cell[b].vy;
/* same center */
st->cell[j].x = st->cell[b].x;
st->cell[j].y = st->cell[b].y;
st->cell[j].age = random_max( 0x0f );
st->cell[j].energy = (st->cell[b].energy);
st->cell[j].rotation =
((double)random()/(double)RAND_MAX)*360.0;
st->cell[j].growth = st->cell[b].growth;
st->cell[j].radius = st->cell[b].radius;
++j;
} else {
st->cell[b].vx = 0.0;
st->cell[b].vy = 0.0;
}
}
st->num_cells = new_num_cells;
}
/* for each find a direction to escape */
if (st->num_cells > 1) {
for (b=0; b<st->num_cells; ++b) {
if (st->cell[b].energy > 0) {
double vx;
double vy;
double len;
/* grow or shrink */
st->cell[b].radius *= st->cell[b].growth;
/* find closest neighbour */
min_dist = 100000.0;
min_index = 0;
for (j=0; j<st->num_cells; ++j) {
if (j!=b) {
const double dx = st->cell[b].x - st->cell[j].x;
const double dy = st->cell[b].y - st->cell[j].y;
if (fabs(dx) < check_dist || fabs(dy) < check_dist) {
const double dist = dx*dx+dy*dy;
/*const double dist = sqrt( dx*dx+dy*dy );*/
if (dist<min_dist) {
min_dist = dist;
min_index = j;
}
}
}
}
/* escape step is away from closest normalized with distance */
vx = st->cell[b].x - st->cell[min_index].x;
vy = st->cell[b].y - st->cell[min_index].y;
len = sqrt( vx*vx + vy*vy );
if (len > 0.0001) {
st->cell[b].vx = vx/len;
st->cell[b].vy = vy/len;
}
st->cell[b].min_dist = len;
/* if not adult (radius too small) */
if (st->cell[b].radius < adult_radius) {
/* if too small 60% stop shrinking */
if (st->cell[b].radius < adult_radius * 0.6) {
st->cell[b].growth = 1.0;
}
/* at safe distance we start growing again */
if (len > grow_dist) {
if (st->cell[b].energy > 30) {
st->cell[b].growth = 1.005;
}
}
} else { /* else keep size */
st->cell[b].growth = 1.0;
}
}
}
} else {
st->cell[0].min_dist = 2*st->move_dist;
}
/* now move em, snack and burn energy */
for (b=0; b<st->num_cells; ++b) {
/* if still alive */
if (st->cell[b].energy > 0) {
/* agility depends on amount of energy */
double fac = (double)st->cell[b].energy / 50.0;
if (fac < 0.0) fac = 0.0;
if (fac > 1.0) fac = 1.0;
st->cell[b].x += fac*(2.0 -
(4.0*(double)random() / (double)RAND_MAX) +
st->cell[b].vx);
st->cell[b].y += fac*(2.0 -
(4.0*(double)random() / (double)RAND_MAX) +
st->cell[b].vy);
/* get older and burn energy */
if (st->cell[b].energy > 0) {
st->cell[b].age++;
st->cell[b].energy--;
}
/* have a snack */
x = ((int)st->cell[b].x)/4;
if (x<0) x=0; if (x>=w4) x = w4-1;
y = ((int)st->cell[b].y)/4;
if (y<0) y=0; if (y>=h4) y = h4-1;
offset = x+y*w4;
/* don't eat if already satisfied */
if (st->cell[b].energy < 100 &&
st->food[offset] > 0) {
st->food[offset]--;
st->cell[b].energy++;
/* if you are hungry, eat more */
if (st->cell[b].energy < 50 &&
st->food[offset] > 0) {
st->food[offset]--;
st->cell[b].energy++;
}
}
}
}
}
