@corollarium/babylon-boids

babylon-boids

A boids library for BabylonJS. Used in the Laje de Santos Virtual Dive project. Check:

• Demo with boxes
• Demo with scary sharks

How to use it

First create your BoidsManager object and associate it with your meshes.

function loadCubes (total, scene) {
    // instantiate our boids manager. Note it doesn't handle the meshes themselves, only the total meshes.
    const boidsManager = new BoidsManager(total, new BABYLON.Vector3(0.0, 0.0, 0.0), 10.0, 10.0);

    // so let's now create our meshes
    const models = [];
    const brickMaterial = new BABYLON.StandardMaterial('brickMaterial', scene);
    brickMaterial.diffuseTexture = new BABYLON.Texture('does_not_exist');
    for (let i = 0; i < total; i++) {
        // create a box
        const box = BABYLON.MeshBuilder.CreateBox(
            'box' + i,
            {
                width: 0.3, height: 0.5, depth: 1.0
            }
        );

        // associate box to boid data. 
        box.boid = boidsManager.boids[i];
        box.material = brickMaterial;
        models.push(box);
    }

    // if you want to get a debug with bounding spheres and velocity vectors
    boidsManager.showDebug();
    boidsManager.gui(scene);

    // so we return 3 things here: the models, the boidsManager, and an update callback
    // for the render loop.
    return {
        models,
        boidsManager,
        update: ((_boids, _models) => {
            return (deltaTime) => {
                // update the boid simulation first
                _boids.update(deltaTime);
                // now apply the calculated positions/orientations to the meshes
                _models.forEach((m) => {
                    m.position.copyFrom(m.boid.position);
                    m.setDirection(m.boid.orientation);
                });
            };
        })(boidsManager, models)
    };
}

Remember to call the update function

    // create a boid block with 20 boids
    const myBoids = loadCubes(20, scene);

    // Register a render loop to repeatedly render the scene
    engine.runRenderLoop(() => {
        const timeDiff = engine.getDeltaTime() / 1000.0;

        // update boids
        myBoids.update(timeDiff);

        scene.render();
    });

API

constructor(total, center, initialRadius = 1.0, boundRadiusScale = 100.0, initialVelocity = null)

Constructor. See parameters for class parameters that can be accessed and changed directly.

int total: Total number of boids in simulation

BABYLON.vector3 center: The center point of the boid volume.

float initialRadius: The radius of the initial boid volume. Boids are distributed randomly within this volume from center when created.

float boundRadiusScale: The bounding volume for the total simulation. Boids are restricted to this volume from center.

BABYLON.vector3 initialVelocity: The inicial velocity for the boids. A small randomness factor is added to each boid.

update(deltaTime)

Updates the boids. Call on every render loop.

Number deltaTime The time since last frame in seconds.

addForce(c)

Adds a force callback function. This enables you to change the simulation with your own forces. Called fr

callback c A valid JS function, called on update() for each boid. Receives as parameters: (BoidsManager, Boid)

showDebug(scene)

Turns on debug visual helpers.

BABYLON.scene scene The scene object.

hideDebug(scene)

Turns off debug visual helpers.

BABYLON.scene scene The scene object.

gui(scene)

Turns on a panel to visually change the boid simulation parameters.

BABYLON.scene scene The scene object.

Parameters

All accessed on the BoidsManager instance.

cohesion Cohesion factor.

separation Separation factor.

alignment Alignment factor.

separationMinDistance The

maxSpeed The maximum allowed speed for a boid, in units per second.

boundsMin The minimum bounds for the valid boid volume.

boundsMax The maximum bounds for the valid boid volume.

LICENSE

MIT