Colored Material Cache

ColoredMaterialCache.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

/// <summary>
/// manages instances of the same material with random colors
/// if a Material+Color combination does not yet exist it will be created
/// if the combination has been created before it will be returned from the cached
/// </summary>
public static class ColoredMaterialCache  {
	/// <summary>
	/// cached materials with random colors
	/// </summary>
	public static Dictionary<Material, Dictionary<int, Material>> ColorVariations {
		get {
			if (_ColorVariations == null) {
				Initialize ();
			}
			return _ColorVariations;
		}
	}
	private static Dictionary<Material, Dictionary<int, Material>> _ColorVariations = null;
	
	/// <summary>
	/// array of random colors, initialize with base colors of Unity
	/// </summary>
	public static Color[] Colors = new Color[] {
		Color.black,
		Color.blue,
		Color.red,
		Color.yellow,
		Color.green,
		Color.white,
		Color.magenta,
		Color.cyan,
		Color.gray
	};
	
	/// <summary>
	/// number of colors
	/// </summary>
	public static int NumberOfColors {
		get {
			if (_NumberOfColors < 0) {
				Initialize ();
			}
			return _NumberOfColors;
		}
	}
	public static int _NumberOfColors = -1;
	
	/// <summary>
	/// last generated color
	/// </summary>
	private	static int LastColor;
	
	/// <summary>
	/// set colors used for randomization
	/// </summary>
	/// <param name="colors">
	/// A list of <see cref="Color"/> that will be used for randomization
	/// </param>
	public static void SetColors (params Color[] colors) {
		int newNumber = colors.Length;
		if (newNumber != NumberOfColors) {
			Colors = new Color[NumberOfColors];
		}
		colors.CopyTo (Colors, 0);
		_NumberOfColors = newNumber;
	}
	
	private static void Initialize () {
		_ColorVariations = new Dictionary<Material, Dictionary<int, Material>> ();
		_NumberOfColors = Colors.Length;
		LastColor = -1;
	}
	
	/// <summary>
	/// Get a variation of Material with a random color picked from the set Colors
	/// </summary>
	/// <param name="mat">
	/// the prototype <see cref="Material"/> based on which the randomization will be generated
	/// </param>
	/// <returns>
	/// A <see cref="Material"/> instance with a random color set to Material.color
	/// </returns>
	public static Material GetVariationOnMaterial (Material mat) {
		Random.seed = Random.Range (1, 23474);
		int colorID = Random.Range (0, NumberOfColors);
		if (colorID == LastColor)
			colorID = (colorID + 1) % NumberOfColors;
		LastColor = colorID;
		if (!ColorVariations.ContainsKey (mat)) {
			ColorVariations.Add (mat, new Dictionary<int, Material> (NumberOfColors));
		}
		
		if (ColorVariations[mat].ContainsKey (colorID)) {
			return ColorVariations[mat][colorID];
		}
		else {
			Material newMat = new Material (mat);
			newMat.color = Colors[colorID];
			ColorVariations[mat].Add (colorID, newMat);
			return newMat;
		}
	}
	
}