koobas.hobune.stream
Randomly place a specific number of objects?
I am trying to fill a space game area with stars (currently just small spheres) and asteroids (currently just medium spheres). The stars are randomly placed with the System.Random function and a string seed. I want the seed to always place the stars and asteroids in the exact same spot each time. I have this part working with the System.Random(string seed) functionality.
The stars have a density limit set by a random number as well (always the same density value based on the same seed). But I want exactly 100 asteroids randomly placed. Is there a code efficient way to place exactly 100 asteroids but in random locations?
int[,] CalcStars(int seed) {
// Using the existing seeded random numbers, place the
// exact same number of starts for this seed every time
System.Random rng = new System.Random (seed);
int[,] stars = new int[100, 100];
for (int x = 0; x < 100; x++) {
for (int y = 0; y < 100; y++) {
string rand = rng.Next ().ToString ();
stars [x, y] = int.Parse(rand.Substring(rand.Length - 1)) < currentSector.starDensity ? 1 : 0;
}
}
return stars;
}
public void DrawStars(GameObject starObject){
// Just cycle through the int[,] stars and every time I find a 1,
// I place a small sphere prefab
int starCount = 0;
for (int x = 0; x < 100; x++) {
for (int y = 0; y < 100; y++) {
if (currentSector.stars [x, y] == 1) {
GameObject star = (GameObject)Instantiate(starObject,new Vector3((x-50)*20,0,(y-50)*20),transform.rotation,transform);
starCount++;
}
}
}
Debug.Log (starCount);
}
int[,] CalcAsteroids() {
// 100x100 is my int[,] - I then multiply it by 20 to essential make
// this 2000x2000 when I actually place the objects
// This also allows me to space them out away from each other
int[,] asteroids = new int[100, 100];
for (int x = 0; x < 100; x++) {
for (int y = 0; y < 100; y++) {
// Place exactly 100 asteroids in the int[,] asteroids
// No more, no less, maintaining a fairly random distribution
// I don't want it to stop at 100 placed otherwise only the
// first part of the map will contain asteroids
// I need to ensure all asteroids are placed, and they aren't all in one area
}
}
return asteroids;
}
I have just looked into "Shuffling" an array - however this would not be based on a seed, thus every time it loads this space sector, the asteroids would be in different spots. So in addition to my question posted - I need to ensure the placement of the 100 asteroids is random by based on the same seed as the stars are generated by (or the Next() of the System.Random).
I got it to work to some degree with a loop of 0 to 99 and my checking 5 times that the entry doesn't exist already. This is the code:
int[,] CalcAsteroids(int seed) {
System.Random rng = new System.Random (seed);
int[,] asteroids = new int[100, 100];
for (int x = 0; x < 100; x++) {
for (int y = 0; y < 100; y++) {
asteroids [x, y] = 0;
}
}
for (int i = 0; i < 100; i++) {
int sampleX = rng.Next (0, 100);
int sampleY = rng.Next (0, 100);
if (asteroids [sampleX, sampleY] == 0) {
asteroids [sampleX, sampleY] = 1;
} else {
sampleX = rng.Next (0, 100);
sampleY = rng.Next (0, 100);
if (asteroids [sampleX, sampleY] == 0) {
asteroids [sampleX, sampleY] = 1;
} else {
sampleX = rng.Next (0, 100);
sampleY = rng.Next (0, 100);
if (asteroids [sampleX, sampleY] == 0) {
asteroids [sampleX, sampleY] = 1;
} else {
sampleX = rng.Next (0, 100);
sampleY = rng.Next (0, 100);
if (asteroids [sampleX, sampleY] == 0) {
asteroids [sampleX, sampleY] = 1;
} else {
sampleX = rng.Next (0, 100);
sampleY = rng.Next (0, 100);
if (asteroids [sampleX, sampleY] == 0) {
asteroids [sampleX, sampleY] = 1;
}
}
}
}
}
}
return asteroids;
}
I'm not 100% sure what you're trying to accomplish with the 2-dimensional array, but wouldn't be a simple loop that creates a random Vector and spawns a star at that point be enough? For Example:
Random rng = new Random(seed);
int starCount = 100;
float width = 100f;
float height = 100f;
float depth = 50f;
for(int i=0; i<starCount;i++){
Vector3 spawnpos = Vector3.zero;
spawnpos.x = rng.Range(-width/2,width/2);
spawnpos.y = rng.Range(-height/2,height/2);
spawnpos.z = rng.Range(-depth/2,depth/2);
Instantiate(starObject,spawnpos,transform.rotation,transform);
}
That might create overlaps of the asteroids. Al all of my solar systems are generated off of a seed, I need to make sure I am not overlapping any. I can also reference where the asteroids are positioned for my map at a later time. I do appreciate your input. I only wish I could implement your more efficient method of creation but I need the location data easily accessible for other game functionality.
