/**
* River generation.
*
* Rivers have a source, and then keep on flowing until they meet another body
* of water, which they flow into, or until they reach the edge of the map.
* Rivers will always flow downhill, except that they can flow a maximum of
* 'river_uphill' uphill. This is to represent the water eroding the higher
* ground lower.
*
* Every possible path for a river will be attempted, in random order, and the
* first river path that can be found that makes the river flow into another
* body of water or off the map will be used.
*
* If no path can be found, then the river's generation will be aborted, and
* false will be returned. true is returned if the river is generated
* successfully.
*/
static bool generate_river_internal(const height_map& heights,
terrain_map& terrain, int x, int y, std::vector<location>& river,
std::set<location>& seen_locations, int river_uphill)
{
const bool on_map = x >= 0 && y >= 0 &&
x < static_cast<long>(heights.size()) &&
y < static_cast<long>(heights.back().size());
if(on_map && !river.empty() && heights[x][y] >
heights[river.back().x][river.back().y] + river_uphill) {
return false;
}
// If we're at the end of the river
if(!on_map || terrain[x][y] == t_translation::SHALLOW_WATER ||
terrain[x][y] == t_translation::DEEP_WATER) {
LOG_NG << "generating river...\n";
// Generate the river
for(std::vector<location>::const_iterator i = river.begin();
i != river.end(); ++i) {
terrain[i->x][i->y] = t_translation::SHALLOW_WATER;
}
LOG_NG << "done generating river\n";
return true;
}
location current_loc(x,y);
location adj[6];
get_adjacent_tiles(current_loc,adj);
static int items[6] = {0,1,2,3,4,5};
std::random_shuffle(items,items+4);
// Mark that we have attempted from this location
seen_locations.insert(current_loc);
river.push_back(current_loc);
for(int a = 0; a != 6; ++a) {
const location& loc = adj[items[a]];
if(seen_locations.count(loc) == 0) {
const bool res = generate_river_internal(heights,terrain,loc.x,loc.y,river,seen_locations,river_uphill);
if(res) {
return true;
}
}
}
river.pop_back();
return false;
}
static std::vector<location> generate_river(const height_map& heights, terrain_map& terrain, int x, int y, int river_uphill)
{
std::vector<location> river;
std::set<location> seen_locations;
const bool res = generate_river_internal(heights,terrain,x,y,river,seen_locations,river_uphill);
if(!res) {
river.clear();
}
return river;
}
bool default_map_generator_job::generate_river_internal(const height_map& heights,
terrain_map& terrain, int x, int y, std::vector<map_location>& river,
std::set<map_location>& seen_locations, int river_uphill)
{
const bool on_map = x >= 0 && y >= 0 &&
x < static_cast<long>(heights.size()) &&
y < static_cast<long>(heights.back().size());
if(on_map && !river.empty() && heights[x][y] >
heights[river.back().x][river.back().y] + river_uphill) {
return false;
}
// If we're at the end of the river
if(!on_map || terrain[x][y] == t_translation::SHALLOW_WATER ||
terrain[x][y] == t_translation::DEEP_WATER) {
LOG_NG << "generating river...\n";
// Generate the river
for(auto i : river) {
terrain[i.x][i.y] = t_translation::SHALLOW_WATER;
}
LOG_NG << "done generating river\n";
return true;
}
map_location current_loc(x,y);
map_location adj[6];
get_adjacent_tiles(current_loc,adj);
std::shuffle(std::begin(adj), std::end(adj), rng_);
// Mark that we have attempted from this map_location
seen_locations.insert(current_loc);
river.push_back(current_loc);
for(const map_location& loc : adj) {
if(seen_locations.count(loc) == 0) {
const bool res = generate_river_internal(heights,terrain,loc.x,loc.y,river,seen_locations,river_uphill);
if(res) {
return true;
}
}
}
river.pop_back();
return false;
}
