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An example of a loot probabilities table based on Unity's Animation and Min Max Curves. Check the explanation post (https://giannisakritidis.com/blog/Animation-And-Min-Max-Curves-In-Unity/)
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| public class LootProbabilities : MonoBehaviour | |
| { | |
| private const int MAX_LEVEL = 20; | |
| private const float MAX_RARITY = 10; | |
| [SerializeField] private ParticleSystem.MinMaxCurve lootRarityPerLevel; | |
| [SerializeField] private AnimationCurve probabilitiesDistribution; | |
| [ReadOnly, SerializeField] private LevelProbabilities[] probabilitiesPerLevel; | |
| private void OnValidate() | |
| { | |
| lootRarityPerLevel.curveMultiplier = 1f; | |
| CalculateChances(); | |
| } | |
| private void Reset() | |
| { | |
| var upperAnimationCurve = AnimationCurve.EaseInOut(0, MAX_RARITY/2, MAX_LEVEL, MAX_RARITY); | |
| var lowerAnimationCurve = AnimationCurve.EaseInOut(0, 0, MAX_LEVEL, MAX_RARITY/2); | |
| probabilitiesDistribution = new AnimationCurve(new Keyframe(0.01f, 0.01f), new Keyframe(1, 1)); | |
| lootRarityPerLevel = new ParticleSystem.MinMaxCurve(1, lowerAnimationCurve, upperAnimationCurve) | |
| { mode = ParticleSystemCurveMode.TwoCurves }; | |
| CalculateChances(); | |
| } | |
| public int GetRarity(int level, float random) => probabilitiesPerLevel[level].GetRarity(random); | |
| private void CalculateChances() | |
| { | |
| var (minRarityAtLevel,maxRarityAtLevel) = RaritySpreadPerLevel(); | |
| probabilitiesPerLevel = new LevelProbabilities[MAX_LEVEL + 1]; | |
| for (int level = 0; level <= MAX_LEVEL; level++) | |
| { | |
| probabilitiesPerLevel[level] = new LevelProbabilities(minRarityAtLevel[level], maxRarityAtLevel[level]); | |
| var chancesSum = CalculateChancesSum(minRarityAtLevel[level], maxRarityAtLevel[level]); | |
| for (int rarity = minRarityAtLevel[level]; rarity <= maxRarityAtLevel[level]; rarity++) | |
| { | |
| var chance = probabilitiesDistribution.Evaluate((float)(rarity - minRarityAtLevel[level]) / | |
| (maxRarityAtLevel[level] - minRarityAtLevel[level])); | |
| probabilitiesPerLevel[level].AddChance(rarity, chance / chancesSum); | |
| } | |
| } | |
| return; | |
| (int[],int[]) RaritySpreadPerLevel() | |
| { | |
| var minRarity = new int[MAX_LEVEL + 1]; | |
| var maxRarity = new int[MAX_LEVEL + 1]; | |
| for (var i = 0; i < MAX_LEVEL + 1; i++) | |
| { | |
| minRarity[i] = (int)lootRarityPerLevel.Evaluate(i, 0f); | |
| maxRarity[i] = (int)lootRarityPerLevel.Evaluate(i, 1f); | |
| } | |
| return (minRarity, maxRarity); | |
| } | |
| float CalculateChancesSum(int minRarity, int maxRarity) | |
| { | |
| float chancesSum = 0; | |
| for (int j = minRarity; j <= maxRarity; j++) | |
| { | |
| var chance = probabilitiesDistribution.Evaluate((float)(j - minRarity) / (maxRarity - minRarity)); | |
| chancesSum += chance; | |
| } | |
| return chancesSum; | |
| } | |
| } | |
| [Serializable] | |
| private class LevelProbabilities | |
| { | |
| [ReadOnly, SerializeField] private List<RarityPercentages> rarityPercentages; | |
| internal LevelProbabilities(int minRarity, int maxRarity) => rarityPercentages = new List<RarityPercentages>(maxRarity - minRarity + 1); | |
| internal void AddChance(int rarity, float chance) => | |
| rarityPercentages.Add(new RarityPercentages | |
| { | |
| rarity = rarity, | |
| chance = (float)Math.Round(Mathf.Clamp(chance * 100f, 0, 100f),2) | |
| }); | |
| internal int GetRarity(float percentageChance) | |
| { | |
| var totalChance = 0f; | |
| foreach (var chance in rarityPercentages) | |
| { | |
| totalChance += chance.chance; | |
| if (percentageChance * 100f <= totalChance) | |
| return chance.rarity; | |
| } | |
| Debug.LogException(new ArgumentOutOfRangeException(nameof(percentageChance), " greater than sum of percentages")); | |
| return -1; | |
| } | |
| [Serializable] | |
| private struct RarityPercentages | |
| { | |
| public int rarity; | |
| public float chance; | |
| } | |
| } | |
| } |
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