private static void AddConnections(GalaxyMap map, List <StarSystem> planets, int nRandomEdges)
{
// First create a spanning tree to ensure that all points are connected in one graph, then add some more edges randomly.
// We could also do Delaunay Triangulation to get a nicer looking graph with neat proximal edges between nodes, but that's quite a bit more work.
MakeSpanningTree(map, planets);
AddRandomEdges(map, planets, nRandomEdges);
}
void Start()
{
map = GetComponent <GalaxyMap>();
List <StarSystem> planets = GenerateRandomPlanets(map, nPlanets, galaxyRadius);
AddConnections(map, planets, nRandomEdges);
}
private static List <StarSystem> GenerateRandomPlanets(GalaxyMap map, int nPlanets, float galaxyRadius)
{
List <StarSystem> planets = new List <StarSystem>(nPlanets);
for (int i = 0; i < nPlanets; ++i)
{
// Calculate random position, but also reduce the vertical position of all planets to get a flat-ish map.
Vector3 pos = Random.insideUnitSphere * galaxyRadius;
pos.y *= 0.1f;
StarSystem newPlanet = map.CreateStar(pos);
planets.Add(newPlanet);
}
return(planets);
}
private static void AddRandomEdges(GalaxyMap map, List <StarSystem> planets, int nRandomEdges)
{
for (int i = 0; i < nRandomEdges; ++i)
{
StarSystem a = planets[Random.Range(0, planets.Count)];
StarSystem b = planets[Random.Range(0, planets.Count)];
// if adding an edge fails, (e.g. due to being a=b or an edge between a and b already existing) then decrement then decrement the counter to ignore this iteration.
bool result = map.Connect(a, b);
if (!result)
{
i--;
}
}
}
/// <summary>
/// Ensure that all planets are connected in a single graph. This method will generally try to keep distances short, but will not guarantee that all distances are the shortest possible.
/// </summary>
private static void MakeSpanningTree(GalaxyMap map, List <StarSystem> planets)
{
Queue <StarSystem> unConnected = new Queue <StarSystem>(planets);
List <StarSystem> connected = new List <StarSystem>(planets.Count);
StarSystem newlyAdding = unConnected.Dequeue();
connected.Add(newlyAdding);
// for each unconnected vertex add it to the graph by finding the nearest connected vertex and making an edge between the two.
while (unConnected.Count > 0)
{
newlyAdding = unConnected.Dequeue();
StarSystem nearest = FindNearest(newlyAdding, connected);
map.Connect(nearest, newlyAdding);
connected.Add(newlyAdding);
}
}