Dream.In.Code > Programming Help > C#

Welcome to Dream.In.Code
	Getting C# Help is Easy! Join 136,542 C# Programmers for FREE! Get instant access to thousands of C# experts, tutorials, code snippets, and more! There are 1,849 people online right now. Registration is fast and FREE... Join Now! Chat LIVE With a C# Expert

Random starmap, certain distance minimum between stars

Random starmap, certain distance minimum between stars, Having issues randomly placing stars that will be >= a specified mi

Options

mroberti	21 Aug, 2008 - 05:38 AM Post #1
New D.I.C Head Joined: 10 Aug, 2008 Posts: 5	OK, I'm ready to kill myself (well not quite!) but I have an issue where I'm trying to place a certain number of stars in random X,Y locations where each one will be no more than 'minimumDistance' away from eachother. That way you don't get dumb placement of stars on top of eachother, etc. Man, I've just been hacking away at it for like a week or so not making much progress. I'm DYIN' ovah heah. Can anyone give me a hand? The whole 'iteration' thing is tying my brain in knots. I'd appreciate any help. Here's what I have so far: CODE using System; using System.Collections.Generic; namespace StarmapDistanceCheck { class Program { // I'm after creating a star object and adding it to an array only after // we've checked that it is no closer than 'minimumDistance' to any other star. public static List<Star> starList; static void Main() { int numberOfStars = 40; starList = new List<Star>(numberOfStars); float minimumDistance = 7.0f; for (int i = 0; i < numberOfStars; i++) { Console.Out.WriteLine("i = " + i); int success = 0; Star tempStar = new Star(); tempStar.starID = i; Console.Out.WriteLine("Created new star"); if (i > 1) { foreach (Star tempStar2 in starList) { double tempDistance = Distance2D(tempStar.x, tempStar.y, tempStar2.x, tempStar2.y); if (tempDistance >= minimumDistance) { Console.Out.WriteLine("Success. Distance from tempStar to star tempStar2 = " + tempDistance + "starList count is:" + starList.Count); success = 1; } else { Console.Out.WriteLine("Failed! Distance: " + tempDistance); while ((tempDistance <= minimumDistance)) { tempStar = new Star(); tempStar.starID = i; tempDistance = Distance2D(tempStar.x, tempStar.y, tempStar2.x, tempStar2.y); } } } } if (i == 0) { success = 1; Console.Out.WriteLine("Star 0="); } if (i == 1) { Star tempStar2 = starList[0]; double testDistance = Distance2D(tempStar.x, tempStar.y, tempStar2.x, tempStar2.y); while (testDistance <= minimumDistance) { testDistance = Distance2D(tempStar.x, tempStar.y, tempStar2.x, tempStar2.y); tempStar.x = RandomHelper.GetRandomFloat(-80.0f, 80.0f); tempStar.y = RandomHelper.GetRandomFloat(-80.0f, 80.0f); //Console.Out.WriteLine("I'm in me loop!"); //Console.Out.WriteLine("Distance = " + testDistance); } success = 1; //Console.Out.WriteLine("Star 1="); } if (success == 1) { starList.Add(tempStar); //Console.Out.WriteLine("Success!"); } else { starList.RemoveAt(i - 1); i = -1; if (i < 0) { i = 0; starList.RemoveAt(0); } } Console.Out.WriteLine("Finished iteration of star:" + tempStar.starID); //Console.ReadLine(); } } public static double Distance2D(float x, float y, float x2, float y2) { return (Math.Sqrt(Math.Pow(Math.Abs(x - x2), 2.0) + Math.Pow(Math.Abs(y - y2), 2.0))); } } public class Star { public float x = RandomHelper.GetRandomFloat(-80.0f, 80.0f); public float y = RandomHelper.GetRandomFloat(-80.0f, 80.0f); public int starID; } // Helper stuff public static class RandomHelper { #region Variables /// <summary> /// Global random generator /// </summary> public static Random globalRandomGenerator = GenerateNewRandomGenerator(); #endregion #region Generate a new random generator /// <summary> /// Generate a new random generator with help of /// WindowsHelper.GetPerformanceCounter. /// Also used for all GetRandom methods here. /// </summary> /// <returns>Random</returns> public static Random GenerateNewRandomGenerator() { globalRandomGenerator = new Random((int)DateTime.Now.Ticks); //needs Interop: (int)WindowsHelper.GetPerformanceCounter()); return globalRandomGenerator; } #endregion #region Get random float and byte methods /// <summary> /// Get random int /// </summary> /// <param name="max">Maximum</param> /// <returns>Int</returns> public static int GetRandomInt(int max) { return globalRandomGenerator.Next(max); } public static int GetRandomInt(int min, int max) { return globalRandomGenerator.Next(min, max); } /// <summary> /// Get random float between min and max /// </summary> /// <param name="min">Min</param> /// <param name="max">Max</param> /// <returns>Float</returns> public static float GetRandomFloat(float min, float max) { return (float)globalRandomGenerator.NextDouble() * (max - min) + min; } #endregion } }
	This Post Was Helpful!


Register for Free to Make These Ads Go Away!

SpiderSpartan	RE: Random Starmap, Certain Distance Minimum Between Stars 21 Aug, 2008 - 06:50 AM Post #2
D.I.C Head Joined: 6 Feb, 2008 Posts: 66 Thanked: 3 times Dream Kudos: 25 My Contributions	First I would separate some of the stuff in main into functions. Instead of doing the distance check iterations in main, maybe make a function that checks the passed star against the starlist. Then in main have a while loop like this. CODE bool success = false; while(!success) { Star tempStar = new Star(); success = GoodDistance(tempStar); } GoodDistance would look like this. CODE GoodDistance(Star tempStar) { foreach (Star tempStar2 in starList) { double tempDistance = Distance2D(tempStar.x, tempStar.y, tempStar2.x, tempStar2.y); if (tempDistance >= minimumDistance) { continue; } else { return false; } } return true; } then after the while loop, you know you have a good star, so add it to the list and stuff. Good luck. This post has been edited by SpiderSpartan: 21 Aug, 2008 - 06:52 AM
	This Post Was Helpful!

SpiderSpartan	RE: Random Starmap, Certain Distance Minimum Between Stars 21 Aug, 2008 - 07:07 AM Post #3
D.I.C Head Joined: 6 Feb, 2008 Posts: 66 Thanked: 3 times Dream Kudos: 25 My Contributions	This should do it for ya. Enjoy. CODE namespace StrarmapDistanceCheck { class Program { // I'm after creating a star object and adding it to an array only after // we've checked that it is no closer than 'minimumDistance' to any other star. public static List<Star> starList; static void Main() { int numberOfStars = 40; starList = new List<Star>(numberOfStars); float minimumDistance = 7.0f; Star tempStar = new Star(); for (int i = 0; i < numberOfStars; i++) { Console.Out.WriteLine("i = " + i); bool success = false; while (!success) { tempStar = new Star(); tempStar.starID = i; success = GoodDistance(tempStar, minimumDistance); } starList.Add(tempStar); //Print Star Location for each star added to starList Console.WriteLine("Star Location: " + tempStar.x + ", " + tempStar.y); } // Print starList ID: X, Y /foreach (Star temp in starList) { Console.WriteLine(temp.starID + ": " + temp.x + ", " + temp.y); }/ } public static bool GoodDistance(Star tempStar, float minimumDistance) { if (starList.Count <= 1) return true; foreach (Star tempStar2 in starList) { double tempDistance = Distance2D(tempStar.x, tempStar.y, tempStar2.x, tempStar2.y); if (tempDistance >= minimumDistance) { continue; } else { return false; } } return true; } public static double Distance2D(float x, float y, float x2, float y2) { return (Math.Sqrt(Math.Pow(Math.Abs(x - x2), 2.0) + Math.Pow(Math.Abs(y - y2), 2.0))); } } public class Star { public float x = RandomHelper.GetRandomFloat(-80.0f, 80.0f); public float y = RandomHelper.GetRandomFloat(-80.0f, 80.0f); public int starID; } // Helper stuff public static class RandomHelper { #region Variables /// <summary> /// Global random generator /// </summary> public static Random globalRandomGenerator = GenerateNewRandomGenerator(); #endregion #region Generate a new random generator /// <summary> /// Generate a new random generator with help of /// WindowsHelper.GetPerformanceCounter. /// Also used for all GetRandom methods here. /// </summary> /// <returns>Random</returns> public static Random GenerateNewRandomGenerator() { globalRandomGenerator = new Random((int)DateTime.Now.Ticks); //needs Interop: (int)WindowsHelper.GetPerformanceCounter()); return globalRandomGenerator; } #endregion #region Get random float and byte methods /// <summary> /// Get random int /// </summary> /// <param name="max">Maximum</param> /// <returns>Int</returns> public static int GetRandomInt(int max) { return globalRandomGenerator.Next(max); } public static int GetRandomInt(int min, int max) { return globalRandomGenerator.Next(min, max); } /// <summary> /// Get random float between min and max /// </summary> /// <param name="min">Min</param> /// <param name="max">Max</param> /// <returns>Float</returns> public static float GetRandomFloat(float min, float max) { return (float)globalRandomGenerator.NextDouble() * (max - min) + min; } #endregion } }
	This Post Was Helpful!

mroberti	RE: Random Starmap, Certain Distance Minimum Between Stars 21 Aug, 2008 - 08:51 AM Post #4
New D.I.C Head Joined: 10 Aug, 2008 Posts: 5	Wow, thanks! I'll give it a shot when I get home! Of course, I COULD try it out while I'm hiding in the datacenter at work. I really appreciate it! I'll let everyone know how it worked in case someone down the road wants to create a starmap with nicely spaced stars!!
	This Post Was Helpful!

baavgai

RE: Random Starmap, Certain Distance Minimum Between Stars
21 Aug, 2008 - 11:38 AM

Post #5

Dreaming Coder

Joined: 16 Oct, 2007
Posts: 2,031

Linux

Thanked: 105 times
Dream Kudos: 475
Expert In: C, C++, Java, C#, ASP.NET, PHP, Perl, Python, Oracle, SQL Server, MySql, HTML, JavaScript, Lua

My Contributions

This was rather amusing. I thought you should be able to take more advantage of objects with this particular program. Since an answer is already on the table, I'll offer this approach. It was entertaining enough I even added a bonus method, "GetClosestStar." Have fun.

csharp


using System;
using System.Collections.Generic;

namespace StarmapDistanceCheck {
	public class Star {
		private float x;
		private float y;
		private int starID;

		public Star(int starID, float x, float y) {
			this.starID = starID;
			this.x = x;
			this.y = y;
		}

		public int StarId { get { return this.starID; } }
		public float X { get { return this.x; } }
		public float Y { get { return this.y; } }

		public float GetDistance(float x, float y) {
			float dx = this.x - x;
			float dy = this.y - y;
			return (float)Math.Sqrt((dx * dx) + (dy * dy));
		}

		public float GetDistance(Star other) {
			return GetDistance(other.x, other.y);
		}

		public override string ToString() {
			return "Star " + this.starID + " (" + this.x + "," + this.y + ")";
		}
	}

	//private float minimumDistance = 7.0f;
	public class StarMap : List<Star> {
		private float minimumDistance;
		private float fieldSize;
		private float hFieldSize;

		public StarMap(float minimumDistance, float fieldSize, int starCount) {
			this.minimumDistance = minimumDistance;
			this.fieldSize = fieldSize;
			hFieldSize = fieldSize / 2.0f;
			InitStars(starCount);
		}

		private float GetRandPos(Random rnd) {
			return ((float)rnd.NextDouble() * fieldSize) - hFieldSize;
		}

		private Star GetNewValidStar(int id, Random rnd) {
			while (true) {
				Star newStar = new Star(id, GetRandPos(rnd), GetRandPos(rnd));
				if (IsValidStar(newStar)) { return newStar; }
			}
		}


		private void InitStars(int starCount) {
			Random rnd = new Random();
			for (int i = 0; i < starCount; i++) {
				this.Add(GetNewValidStar(i, rnd));
			}
		}

		public bool IsValidStar(Star newStar) {
			foreach (Star currentStar in this) {
				if (newStar.GetDistance(currentStar) < minimumDistance) { return false; }
			}
			return true;
		}

		public Star GetClosestStar(Star toStar) {
			Star closest = null;
			float lastDist = -1;
			foreach (Star star in this) {
				if (toStar != star ) {
					float dist = star.GetDistance(toStar);
					if (dist < lastDist || lastDist==-1) {
						closest = star;
						lastDist = dist;
					}
				}
			}
			return closest;
		}

		public float MinimumDistance { get { return this.minimumDistance; } }

	}

	class Program {
		static void Main() {
			StarMap starMap = new StarMap(7.0f, 160, 40);
			foreach (Star star in starMap) {
				Console.WriteLine(star + " : " + starMap.GetClosestStar(star).GetDistance(star));
			}
			Console.ReadLine();
		}

	}

}

This Post Was Helpful!

mroberti	RE: Random Starmap, Certain Distance Minimum Between Stars 21 Aug, 2008 - 03:05 PM Post #6
New D.I.C Head Joined: 10 Aug, 2008 Posts: 5	Thanks baavgai! Bonus features, always nice! I'm thinking of linking to this post in the gamedev forum here too. Someone HAS to have run into this before!
	This Post Was Helpful!

mroberti	RE: Random Starmap, Certain Distance Minimum Between Stars 24 Aug, 2008 - 04:13 PM Post #7
New D.I.C Head Joined: 10 Aug, 2008 Posts: 5	Hot damn! I got it implemented. Thanks for the help guys! I'm glad you showed me the method to do it in. Makes perfect sense the way you guys did it! That's a wrap!
	This Post Was Helpful!