范围滑块的逻辑： min(min, max) 有效但 max(min, max) 无效

编程问答 2022-05-25

问题描述

我有以下代码：

public class Test : UnityEngine.MonoBehavIoUr
{
    [Range(0.0f,1.0f)] // draws a slider restricted to 0.0 <-> 1.0 range in UI
    public float RangeMin = 0.0f;

    [Range(0.0f,1.0f)] // draws a slider restricted to 0.0 <-> 1.0 range in UI
    public float RangeMax = 1.0f;

    private void OnValidate() // called at every update in UI to validate/coerce
    {
        RangeMin = math.min(RangeMin,RangeMax);
        RangeMax = math.max(RangeMin,RangeMax);
    }
}

目前，它执行以下操作：

改变最小值永远不会影响最大值：（期望的行为）

enter image description here

改变最大值确实影响最小值：（不需要的行为）

enter image description here

这段非常简单的代码适用于最小滑块，但不适用于最大滑块。

注意，请不要建议使用 EditorGUI.MinMaxSlider，因为它不显示值：

enter image description here

解决方法

您的问题是订单：

private void OnValidate() // called at every update in UI to validate/coerce
{
    RangeMin = math.min(RangeMin,RangeMax);
    RangeMax = math.max(RangeMin,RangeMax);
}

它对 RangeMin“有效”，因为您在更改它的那一刻立即检查并限制它。

但是，在更改 RangeMax 时，您已经立即影响了 RangeMin，之前它有机会限制 RangeMax！

按照建议，您应该检查当前正在更改的两个值中的哪一个，例如喜欢

[HideInInspector] private float lastMin;
[HideInInspector] private float lastMax;

private void OnValidate() 
{
    if(!Mathf.Approximately(lastMin,RangeMin))
    {
        RangeMin = Mathf.Min(RangeMin,RangeMax);
        lastMin = RangeMin;
    }

    if(!Mathf.Approximately(lastMax,RangeMax))
    {
        RangeMax = Mathf.Max(RangeMin,RangeMax);
        lastMax = RangeMax;
    }
}

评论中已经提到的另一种替代方法是使用局部变量来存储钳位值，但等待分配直到所有值都完成钳位，例如

private void OnValidate() 
{     
    var newMin = Mathf.Min(RangeMin,RangeMax);        
    var newMax = Mathf.Max(RangeMin,RangeMax);

    RangeMin = newMin;
    RangeMax = newMax;
}

或者回到

注意，请不要建议使用 EditorGUI.MinMaxSlider，因为它不显示值。

我想你可以简单地让它像Naughty Attributes

已经完成一样 
namespace NaughtyAttributes
{
    [AttributeUsage(AttributeTargets.Field,AllowMultiple = false,Inherited = true)]
    public class MinMaxSliderAttribute : DrawerAttribute
    {
        public float MinValue { get; private set; }
        public float MaxValue { get; private set; }

        public MinMaxSliderAttribute(float minValue,float maxValue)
        {
            MinValue = minValue;
            MaxValue = maxValue;
        }
    }
}

还有抽屉

namespace NaughtyAttributes.Editor
{
    [CustomPropertyDrawer(typeof(MinMaxSliderAttribute))]
    public class MinMaxSliderPropertyDrawer : PropertyDrawerBase
    {
        protected override float GetPropertyHeight_Internal(SerializedProperty property,GUIContent label)
        {
            return (property.propertyType == SerializedPropertyType.Vector2)
                ? GetPropertyHeight(property)
                : GetPropertyHeight(property) + GetHelpBoxHeight();
        }

        protected override void OnGUI_Internal(Rect rect,SerializedProperty property,GUIContent label)
        {
            EditorGUI.BeginProperty(rect,label,property);

            MinMaxSliderAttribute minMaxSliderAttribute = (MinMaxSliderAttribute)attribute;

            if (property.propertyType == SerializedPropertyType.Vector2)
            {
                EditorGUI.BeginProperty(rect,property);

                float indentLength = NaughtyEditorGUI.GetIndentLength(rect);
                float labelWidth = EditorGUIUtility.labelWidth + NaughtyEditorGUI.HorizontalSpacing;
                float floatFieldWidth = EditorGUIUtility.fieldWidth;
                float sliderWidth = rect.width - labelWidth - 2.0f * floatFieldWidth;
                float sliderPadding = 5.0f;

                Rect labelRect = new Rect(
                    rect.x,rect.y,labelWidth,rect.height);

                Rect sliderRect = new Rect(
                    rect.x + labelWidth + floatFieldWidth + sliderPadding - indentLength,sliderWidth - 2.0f * sliderPadding + indentLength,rect.height);

                Rect minFloatFieldRect = new Rect(
                    rect.x + labelWidth - indentLength,floatFieldWidth + indentLength,rect.height);

                Rect maxFloatFieldRect = new Rect(
                    rect.x + labelWidth + floatFieldWidth + sliderWidth - indentLength,rect.height);

                // Draw the label
                EditorGUI.LabelField(labelRect,label.text);

                // Draw the slider
                EditorGUI.BeginChangeCheck();

                Vector2 sliderValue = property.vector2Value;
                EditorGUI.MinMaxSlider(sliderRect,ref sliderValue.x,ref sliderValue.y,minMaxSliderAttribute.MinValue,minMaxSliderAttribute.MaxValue);

                sliderValue.x = EditorGUI.FloatField(minFloatFieldRect,sliderValue.x);
                sliderValue.x = Mathf.Clamp(sliderValue.x,Mathf.Min(minMaxSliderAttribute.MaxValue,sliderValue.y));

                sliderValue.y = EditorGUI.FloatField(maxFloatFieldRect,sliderValue.y);
                sliderValue.y = Mathf.Clamp(sliderValue.y,Mathf.Max(minMaxSliderAttribute.MinValue,sliderValue.x),minMaxSliderAttribute.MaxValue);

                if (EditorGUI.EndChangeCheck())
                {
                    property.vector2Value = sliderValue;
                }

                EditorGUI.EndProperty();
            }
            else
            {
                string message = minMaxSliderAttribute.GetType().Name + " can be used only on Vector2 fields";
                DrawDefaultPropertyAndHelpBox(rect,property,message,MessageType.Warning);
            }

            EditorGUI.EndProperty();
        }
    }
}

最后是什么样子

[SerializeField] [MinMaxSlider(0f; 100f)] private float _minMaxSlider;

enter image description here

现在在复制该代码之前，请注意 Naughty Attributes Package 在 Unity Asset Store 中免费提供，并且对编辑器（ReorderableList、Button、{{ 1}} 等) ;)

c#c#clamprangeunity3dunity3d