int neighborValue(const Raster &raster, int x, int y, bool isTorus)
{
int numNeighbours = 0;
for (int yy = y-1; yy <= y+1; yy++) {
for (int xx = x-1; xx <= x+1; xx++) {
if (xx == x && yy == y) {
continue; // not a neighbour
}
bool inBounds = raster.inBounds(xx,yy);
if (!isTorus && !inBounds) {
continue; // i.e. dead
}
int actualX = xx;
int actualY = yy;
if (!inBounds) {
// transform to torus
actualX = (xx + raster.width) % raster.width;
actualY = (yy + raster.height) % raster.height;
}
const int currentCellState = raster.data[raster.index(actualX, actualY)];
if (currentCellState == ALIVE) {
numNeighbours++;
}
}
}
const int cellState = raster.data[raster.index(x,y)];
// apply rules
int newState = DEAD;
if (cellState == DEAD && numNeighbours == 3) {
newState = ALIVE;
} else if (cellState == ALIVE && (numNeighbours == 2 || numNeighbours == 3)) {
newState = ALIVE;
}
return newState;
}
void simulateNextState(Raster &raster, bool isTorus)
{
const int width = raster.width;
const int height = raster.height;
int* data = new int[width*height];
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
int index = raster.index(x,y);
data[index] = neighborValue(raster, x, y, isTorus);
}
}
delete[] raster.data;
raster.data = data;
}
void simulateInvasion(Raster &raster, float invasionFactor)
{
if (invasionFactor <= 0)
{
return;
}
for (int y = 0; y < raster.height; ++y) {
for (int x = 0; x < raster.width; ++x) {
float random = static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
if (random < invasionFactor) {
int index = raster.index(x,y);
// flip cell state
raster.data[index] = (raster.data[index] + 1) % 2;
}
}
}
}
