Random rated object picker unity extension

RandomRateObject.cs

using System;
using Object = UnityEngine.Object;
using Random = UnityEngine.Random;

[Serializable]
public class RandomRateObject<T> : RandomRateObjectBase where T : Object {
    // rates.Length + 1 = objects.Length
    public float[] rates = new float[0];
    public T[] objects = new T[1];

    public T PickOne() {
        int i = 0;
        var cur = 0f;
        for (; i < rates.Length; i++) {
            cur += rates[i];
            if (Random.Range(0, 1f) < cur) {
                return objects[i];
            }
        }
        return objects[i];
    }
}

public class RandomRateObjectBase {}

RandomRateObjectDrawer.cs

using UnityEditor;
using UnityEngine;

[CustomPropertyDrawer(typeof(RandomRateObjectBase), true)]
public class RandomRateGameObjectDrawer : PropertyDrawer {
    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label) {
        var rates = property.FindPropertyRelative("rates");
        var objects = property.FindPropertyRelative("objects");
        var type = property.serializedObject.targetObject
            .GetType()
            .GetField(property.propertyPath)
            .FieldType
            .BaseType
            .GetGenericArguments()[0];

        var fullRect = position;
        var height = position.height / (rates.arraySize + 3);

        EditorGUI.BeginProperty(fullRect, label, property);

        var labelRect = new Rect(fullRect.x, fullRect.y, fullRect.width, height);
        EditorGUI.LabelField(labelRect, label);

        var total = 0f;
        int i = 0;
        var objWidth = 150;
        for (; i < rates.arraySize; i++) {
            var objRect = new Rect(fullRect.x, fullRect.y + height * (i + 1), objWidth, height);
            var rect = new Rect(fullRect.x + objWidth, fullRect.y + height * (i + 1), fullRect.width - objWidth, height);
            var rate = rates.GetArrayElementAtIndex(i);
            var val = rate.floatValue;
            var obj = objects.GetArrayElementAtIndex(i);

            var objNewValue = EditorGUI.ObjectField(objRect, obj.objectReferenceValue, type, true);
            obj.objectReferenceValue = objNewValue;
            obj.serializedObject.ApplyModifiedProperties();

            val = EditorGUI.Slider(rect, val, 0, 1);
            val = Mathf.Clamp(val, val, 1f - total);
            rate.floatValue = val;
            rate.serializedObject.ApplyModifiedProperties();
            total += val;
        }

        i++;
        var leftObjRect = new Rect(fullRect.x, fullRect.y + height * i, objWidth, height);
        var leftRect = new Rect(fullRect.x + objWidth, fullRect.y + height * i, fullRect.width - objWidth, height);
        var leftObj = objects.GetArrayElementAtIndex(objects.arraySize - 1);

        var leftObjNewVal = EditorGUI.ObjectField(leftObjRect, leftObj.objectReferenceValue, type, true);
        leftObj.objectReferenceValue = leftObjNewVal;
        leftObj.serializedObject.ApplyModifiedProperties();
        EditorGUI.Slider(leftRect, 1f - total, 0, 1);

        i++;
        var btnWidth = fullRect.width / 2;
        var leftBtnRect = new Rect(fullRect.x, fullRect.y + height * i, btnWidth, height);
        var rightBtnRect = new Rect(fullRect.x + btnWidth, fullRect.y + height * i, btnWidth, height);
        if (GUI.Button(leftBtnRect, "+1")) {
            rates.InsertArrayElementAtIndex(rates.arraySize);
            objects.InsertArrayElementAtIndex(objects.arraySize);

        }
        if (GUI.Button(rightBtnRect, "-1")) {
            if (rates.arraySize <= 0) {
                return;
            }
            rates.DeleteArrayElementAtIndex(rates.arraySize - 1);
            objects.DeleteArrayElementAtIndex(objects.arraySize - 1);
        }

        EditorGUI.EndProperty();
    }

    public override float GetPropertyHeight(SerializedProperty property, GUIContent label) {
        return 16 * (property.FindPropertyRelative("rates").arraySize + 4);
    }
}