Aabb in JavaScript

Introduction

Aabb stands for "Axis-aligned bounding box". It is a geometric shape that represents a three-dimensional object based on its extreme points. In other words, it's the smallest box that can fit around an object, and its sides are always parallel to the X, Y, and Z axes.

In JavaScript, aabb can be implemented using objects to represent the minimum and maximum points of the box.

Implementation

Here is an example implementation of aabb in JavaScript:

class Aabb {
  constructor(min, max) {
    this.min = min;
    this.max = max;
  }

  /**
   * Check if another aabb is intersecting with this one.
   */
  isIntersecting(other) {
    return (
      this.max.x >= other.min.x &&
      this.max.y >= other.min.y &&
      this.max.z >= other.min.z &&
      this.min.x <= other.max.x &&
      this.min.y <= other.max.y &&
      this.min.z <= other.max.z
    );
  }

  /**
   * Check if a point is inside this aabb.
   */
  containsPoint(point) {
    return (
      point.x >= this.min.x &&
      point.y >= this.min.y &&
      point.z >= this.min.z &&
      point.x <= this.max.x &&
      point.y <= this.max.y &&
      point.z <= this.max.z
    );
  }
}

Usage

To create an aabb for an object, you need to find its extreme points. This can be done by iterating over its vertices and finding the minimum and maximum for each coordinate.

const vertices = [
  { x: 1, y: 2, z: 3 },
  { x: 4, y: 5, z: 6 },
  { x: 7, y: 8, z: 9 }
];

let min = { x: Infinity, y: Infinity, z: Infinity };
let max = { x: -Infinity, y: -Infinity, z: -Infinity };

for (const vertex of vertices) {
  min.x = Math.min(min.x, vertex.x);
  min.y = Math.min(min.y, vertex.y);
  min.z = Math.min(min.z, vertex.z);
  max.x = Math.max(max.x, vertex.x);
  max.y = Math.max(max.y, vertex.y);
  max.z = Math.max(max.z, vertex.z);
}

const objectAabb = new Aabb(min, max);

Once you have created your aabb, you can use its methods to check for collisions or containment. For example, to check if two objects are colliding:

const objectA = new Aabb({ x: 1, y: 2, z: 3 }, { x: 4, y: 5, z: 6 });
const objectB = new Aabb({ x: 3, y: 4, z: 5 }, { x: 6, y: 7, z: 8 });

if (objectA.isIntersecting(objectB)) {
  console.log('Objects are colliding!');
}

Conclusion

Aabb is a simple yet powerful way to represent 3D objects in JavaScript. By using it, programmers can easily implement collision detection and containment checking in their 3D applications.