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Assets/Editor/DrawIfPropertyDrawer.cs

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+
+using UnityEditor;
+using UnityEngine;
+
+/// <summary>
+/// Based on: https://forum.unity.com/threads/draw-a-field-only-if-a-condition-is-met.448855/
+/// </summary>
+[CustomPropertyDrawer(typeof(DrawIfAttribute))]
+public class DrawIfPropertyDrawer : PropertyDrawer
+{
+    #region Fields
+
+    // Reference to the attribute on the property.
+    DrawIfAttribute drawIf;
+
+    // Field that is being compared.
+    SerializedProperty comparedField;
+
+    #endregion
+
+    public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
+    {
+        if (!ShowMe(property) && drawIf.disablingType == DrawIfAttribute.DisablingType.DontDraw)
+            return 0f;
+
+        // The height of the property should be defaulted to the default height.
+        return base.GetPropertyHeight(property, label);
+    }
+
+    private bool ShowMe(SerializedProperty property)
+    {
+        drawIf = attribute as DrawIfAttribute;
+        // Replace propertyname to the value from the parameter
+        string path = property.propertyPath.Contains(".") ? System.IO.Path.ChangeExtension(property.propertyPath, drawIf.comparedPropertyName) : drawIf.comparedPropertyName;
+
+        comparedField = property.serializedObject.FindProperty(path);
+
+        if (comparedField == null)
+        {
+            Debug.LogError("Cannot find property with name: " + path);
+            return true;
+        }
+
+        // get the value & compare based on types
+        switch (comparedField.type)
+        { // Possible extend cases to support your own type
+            case "bool":
+                switch (drawIf.comparisonMethod)
+                {
+                    case DrawIfAttribute.Comparator.Equal:
+                        return comparedField.boolValue.Equals(drawIf.comparedValue);
+                    case DrawIfAttribute.Comparator.NotEqual:
+                        return !comparedField.boolValue.Equals(drawIf.comparedValue);
+                    default:
+                        Debug.LogError("Error: Comparison method: "+drawIf.comparisonMethod+" does not exist");
+                        return true;
+                }
+            case "Enum":
+                switch (drawIf.comparisonMethod)
+                {
+                    case DrawIfAttribute.Comparator.Equal:
+                        return comparedField.enumValueIndex.Equals((int)drawIf.comparedValue);
+                    case DrawIfAttribute.Comparator.NotEqual:
+                        return !comparedField.enumValueIndex.Equals((int)drawIf.comparedValue);
+                    default:
+                        Debug.LogError("Error: Comparison method: " + drawIf.comparisonMethod + " does not exist");
+                        return true;
+                }
+            default:
+                Debug.LogError("Error: " + comparedField.type + " is not supported of " + path);
+                return true;
+        }
+    }
+
+    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
+    {
+        // If the condition is met, simply draw the field.
+        if (ShowMe(property))
+        {
+            EditorGUI.PropertyField(position, property);
+        } //...check if the disabling type is read only. If it is, draw it disabled
+        else if (drawIf.disablingType == DrawIfAttribute.DisablingType.ReadOnly)
+        {
+            GUI.enabled = false;
+            EditorGUI.PropertyField(position, property);
+            GUI.enabled = true;
+        }
+    }
+
+}

Assets/Editor/DrawIfPropertyDrawer.cs.meta

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