object not an instance of THREE.Object3D 报错原因

当您在Three.js中使用一个不是THREE.Object3D实例的对象时，就会出现"object not an instance of THREE.Object3D"的错误。这个错误通常发生在以下两种情况下：

1. 您试图将一个不是THREE.Object3D实例的对象添加到THREE.Scene或THREE.Object3D中。在这种情况下，您需要确保您要添加的对象是THREE.Object3D的实例。例如，如果您有一个自定义的Mesh对象，您需要确保它继承自THREE.Object3D。

2. 您试图访问一个不是THREE.Object3D实例的对象的属性或方法。在这种情况下，您需要确保您在访问对象的属性或方法之前检查了它是否是THREE.Object3D的实例。

解决这个问题的方法是确保您正在使用THREE.Object3D的实例，或者在访问对象的属性或方法之前检查它是否是THREE.Object3D的实例。例如，您可以使用以下代码来检查对象是否是THREE.Object3D的实例：

if (object instanceof THREE.Object3D) {
  // 对象是THREE.Object3D的实例
} else {
  // 对象不是THREE.Object3D的实例
}

如果您仍然遇到问题，可以检查您的代码并查看是否有其他可能导致对象不是THREE.Object3D实例的问题。

相关问题

Uncaught TypeError: THREE.Loader.load is not a function

This error occurs when trying to use the function `THREE.Loader.load()` but it is not defined or available in the current scope.

To resolve this issue, ensure that you have imported the necessary Three.js libraries and that they are properly loaded before attempting to use `THREE.Loader.load()`.

You can also check if there is a typo in the function name or that the version of the Three.js library you are using supports the `load()` function.

Here is an example of importing the necessary libraries for Three.js and using `THREE.Loader.load()`:

import * as THREE from 'three';
import {OBJLoader} from 'three/examples/jsm/loaders/OBJLoader.js';

const loader = new OBJLoader();
loader.load(
    'model.obj',
    function ( object ) {
        scene.add( object );
    },
    function ( xhr ) {
        console.log( ( xhr.loaded / xhr.total * 100 ) + '% loaded' );
    },
    function ( error ) {
        console.log( 'An error happened' );
    }
);

In this example, we are importing the `THREE` library and the `OBJLoader` from the `three/examples/jsm/loaders` directory. We then create a new instance of the `OBJLoader` and use the `load()` function to load a 3D model.

class Program { static void Main(string[ ] args) { Person David = new Person(); Person Alice = new Person(); // Initialize David David.age = 21; David.name = "David"; David.weight = 185.4; David.height = 72.3; // Initialize Alice Alice.age = 18; Alice.name = "Alice"; Alice.weight = 125.7; Alice.height = 67.1; // print some values Console.WriteLine("David’s age = {0}; David’s weight = {1}",David.age, David.weight); Console.WriteLine("Alice’s age = {0}; Alice’s weight = {1}", Alice.age, Alice.weight); } } Add this code to Program.cs. Compile and run it. Modify this code to print all of the instance variables of David and Alice. Run and understand the code. Add comments to record your understanding. Encapsulation in C#: In the previous example, we accessed the characteristics of the Person Class directly because the attributes (e.g. name, age, etc.) are defined as ‘public’. This is not a good practice and actually should be avoided in order to have ‘encapsulation’ – one of three most important features of object oriented design. The better option and practice is to define the attributes ‘private’ and then design some public methods to access them, normally ‘getXXX’ and ‘setXXX’. Amend the codes above accordingly. (Task 1.2)

class Person
{
private int age;
private string name;
private double weight;
private double height;

public int GetAge()
{
return age;
}

public void SetAge(int newAge)
{
age = newAge;
}

public string GetName()
{
return name;
}

public void SetName(string newName)
{
name = newName;
}

public double GetWeight()
{
return weight;
}

public void SetWeight(double newWeight)
{
weight = newWeight;
}

public double GetHeight()
{
return height;
}

public void SetHeight(double newHeight)
{
height = newHeight;
}
}

class Program
{
static void Main(string[] args)
{
Person David = new Person();
Person Alice = new Person();

// Initialize David
David.SetAge(21);
David.SetName("David");
David.SetWeight(185.4);
David.SetHeight(72.3);

// Initialize Alice
Alice.SetAge(18);
Alice.SetName("Alice");
Alice.SetWeight(125.7);
Alice.SetHeight(67.1);

// Print all instance variables of David
Console.WriteLine("David: age = {0}, name = {1}, weight = {2}, height = {3}", David.GetAge(), David.GetName(), David.GetWeight(), David.GetHeight());

// Print all instance variables of Alice
Console.WriteLine("Alice: age = {0}, name = {1}, weight = {2}, height = {3}", Alice.GetAge(), Alice.GetName(), Alice.GetWeight(), Alice.GetHeight());
}
}

In the modified code, the attributes (age, name, weight, height) of the Person class are defined as private. We have added public methods (getters and setters) to access and modify these attributes. By encapsulating the attributes, we achieve data hiding and provide controlled access to them.

The getters (e.g., GetAge, GetName, etc.) are used to retrieve the values of the private attributes, and the setters (e.g., SetAge, SetName, etc.) are used to set new values for the attributes.

In the Main method, we now use the setters to initialize the attributes for David and Alice. When printing the values, we use the getters to retrieve the attribute values.

Encapsulation is a fundamental concept in object-oriented programming that promotes data integrity and helps maintain code flexibility and reusability. By encapsulating the attributes, we can control access to them and enforce data validation or business logic if needed.