DirectionalLightHelper.update()

The update() method is a part of the DirectionalLightHelper class in the Three.js library. This method is used to update the helper geometry to the position and direction of the light it is assigned to.

Syntax

helper.update()

Parameters

This method does not take any parameters.

Return Value

This method does not return any value.

Description

The DirectionalLightHelper is a class that is used to visually represent a DirectionalLight in the scene. It creates a visible line that shows the direction and position of the light. The update() method is used to keep that line in sync with the actual position and direction of the light.

When you create a DirectionalLightHelper object, you pass the light object that it should be assigned to as a parameter. Once assigned, the helper will automatically track the position and direction of that light object. However, if the light object changes position or direction during the course of the program, the helper object will not automatically update itself to match.

That's where the update() method comes in. The update() method should be called every frame (or whenever the light changes position or direction) to redraw the helper line so that it always matches the light.

Example

Here is an example that shows how to create a DirectionalLight and a DirectionalLightHelper, and then update the helper every frame using the update() method:

// Create a DirectionalLight
const light = new THREE.DirectionalLight(0xffffff, 1);
light.position.set(0, 10, 0);
scene.add(light);

// Create a DirectionalLightHelper and assign it to the light
const helper = new THREE.DirectionalLightHelper(light, 5);
scene.add(helper);

// Render loop
function animate() {
    // Update the helper every frame
    helper.update();

    // Render the scene
    renderer.render(scene, camera);

    // Request the next frame
    requestAnimationFrame(animate);
}

animate();

In this example, we create a DirectionalLight, add it to the scene, and then create a DirectionalLightHelper object and assign it to the light. We pass in a size parameter to control the length of the helper line.

Then, in the render loop, we call the update() method on the helper object to keep it in sync with the light. Finally, we render the scene and request the next frame.

Conclusion

The update() method of the DirectionalLightHelper class is a simple but important method that is used to keep the helper geometry in sync with the position and direction of the light that it represents. By calling this method every frame (or every time the light changes), you can ensure that your helper always shows the correct information.