Function floodRegion

Source/ThirdParty/recastnavigation/RecastRegion.cpp:252–350

static bool floodRegion(int x, int y, int i,
						unsigned short level, unsigned short r,
						rcCompactHeightfield& chf,
						unsigned short* srcReg, unsigned short* srcDist,
						rcTempVector<LevelStackEntry>& stack)
{
	const int w = chf.width;
	
	const unsigned char area = chf.areas[i];
	
	// Flood fill mark region.
	stack.clear();
	stack.push_back(LevelStackEntry(x, y, i));
	srcReg[i] = r;
	srcDist[i] = 0;
	
	unsigned short lev = level >= 2 ? level-2 : 0;
	int count = 0;
	
	while (stack.size() > 0)
	{
		LevelStackEntry& back = stack.back();
		int cx = back.x;
		int cy = back.y;
		int ci = back.index;
		stack.pop_back();
		
		const rcCompactSpan& cs = chf.spans[ci];
		
		// Check if any of the neighbours already have a valid region set.
		unsigned short ar = 0;
		for (int dir = 0; dir < 4; ++dir)
		{
			// 8 connected
			if (rcGetCon(cs, dir) != RC_NOT_CONNECTED)
			{
				const int ax = cx + rcGetDirOffsetX(dir);
				const int ay = cy + rcGetDirOffsetY(dir);
				const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(cs, dir);
				if (chf.areas[ai] != area)
					continue;
				unsigned short nr = srcReg[ai];
				if (nr & RC_BORDER_REG) // Do not take borders into account.
					continue;
				if (nr != 0 && nr != r)
				{
					ar = nr;
					break;
				}
				
				const rcCompactSpan& as = chf.spans[ai];
				
				const int dir2 = (dir+1) & 0x3;
				if (rcGetCon(as, dir2) != RC_NOT_CONNECTED)
				{
					const int ax2 = ax + rcGetDirOffsetX(dir2);
					const int ay2 = ay + rcGetDirOffsetY(dir2);
					const int ai2 = (int)chf.cells[ax2+ay2*w].index + rcGetCon(as, dir2);