📖 INDEX
Frustum
THREE.JS REFERENCE // frustum
Frustums are used to determine what is inside the camera's field of view.
Syntax
const frustum = new THREE.Frustum();Visual Explanation
Performance
In 3D graphics, instancing and managing GPU memory is critical. Mismanaging Frustum can lead to an excess of draw calls or memory leaks, severely dropping the frames per second (FPS).
Examples
const frustum = new THREE.Frustum();Real-world Use Cases
import * as THREE from 'three';
const scene = new THREE.Scene();
// Using Frustum in a scene setup
const instance = new Frustum();
scene.add(instance);Common Mistakes
X Re-instantiating Geometries, Materials or Frustum inside the render loop.
✓ Always instantiate objects outside the render loop and reuse them or update their properties dynamically.
// Bad
function animate() {
const item = new Frustum(); // Memory leak!
requestAnimationFrame(animate);
}
// Good
const item = new Frustum();
function animate() {
item.rotation.y += 0.01;
requestAnimationFrame(animate);
}When NOT to use it
Scenario
When standard 2D Canvas or simple DOM elements suffice.
Alternative
Three.js and WebGL bring significant overhead. Don't use them for basic UI elements or static 2D images.
Differences
| Function | Difference |
|---|---|
| Raw WebGL | Writing raw WebGL requires hundreds of lines of boilerplate just to draw a triangle. Frustum abstracts the underlying matrix math and buffer handling into a friendly API. |
Best Practices
- Consult the official Three.js documentation for deeper understanding.
- Be mindful of performance when creating many objects or geometries.
Interview Question
How do you optimize a scene that heavily relies on Frustum?▼
Hint: Think about InstancedMesh, merged geometries, and reducing draw calls.
You should aim to minimize draw calls by merging geometries if they share the same material, using InstancedMesh for identical objects, and properly calling .dispose() on materials/geometries when they are no longer needed to free GPU memory.
Exercises
HardCreate a scene utilizing Frustum while keeping the FPS above 60.View Solution
const instance = new Frustum();
// Proper disposal logic
window.addEventListener('unload', () => {
instance.dispose();
});