BABYLON-STEERING

Intro

A steering behaviors library for Babylon.js for moving entities in the x/z plane. The library was born thanks to these tutorials and the library three-steer.

The following behavious are supported:

• Seek, Seek with Arrive and Attract (Seek with intensity)
• Flee
• Arrive
• Pursue
• Evade
• Interpose
• Wander
• Collision Avoidance
• Follow Path
• Follow Leader
• Queue
• Cohesion, separation and alignment (Flocking)
• Hide
• Apply general force

Steering Entities can:

• look at a specific target with the .lookAt() method
• look where they are going with the .lookWhereGoing() method

How to setup

Include babylon-steering library:

import SteeringVehicle from 'babylon-steering';

Create a Babylon.js 3D scene with a mesh and simply instantiate a Steering Entity linked to this mesh (passing the engine to have the engine.getDeltaTime() and move the entities accordingly ):

const redSphere = new SteeringVehicle(my_mesh, engine, options);

/*
    options can be:

    options.maxSpeed || 0.2;
    options.mass || 1;

    // ARRIVAL
    options.arrivalThreshold || 100;

    // AVOID
    options.avoidDistance || 120;
    options.radius || 100;

    // WANDER
    options.wanderDistance || 10;
    options.wanderAngle || 10;
    options.wanderRadius || 5;
    options.wanderRange || 20;

    // QUEUE
    options.inSightDistance || 200;
    options.tooCloseDistance || 60;
*/

Add the behavior/s to the steering entity and the update method inside main render/animation loop:

scene.executeWhenReady(function () {
        engine.runRenderLoop(function () {

            my_mesh
                .seekWithArrive(greenTarget, 50)
                .hasInConeOfView(arrayOfEnemies)
                .avoid(obstacleIstances)
                .applyForce(new BABYLON.Vector3(1, 0, 0.75))    // For istance can be WIND...
                .lookWhereGoing(true);

            my_mesh.animate();  // Update the Steering Vehicle

            scene.render();
        });
});

Combine behaviours

It is possible to combine many simultaneous steering forces by passing the following parameters to the .animate() function according to the four methods described in this bog post:

• priority for Priority Arbitration
• weighted for Weighted Blending,
• probability for 'Prioritised Dithering'
• truncated for 'Weighted Prioritised Truncated Sum'

scene.executeWhenReady(function () {
        engine.runRenderLoop(function () {

            blueSphere
                .seek(greenBox, 50, { weigth: 1.7, priority: 1, probability: 0.6 })
                .flee(redSphere, 160, { weigth: 0.5, priority: 5, probability: 0.6 })
                .lookTarget(redSphere) // or .lookWhereGoing(true)
                .avoid(obstacleIstances, { weigth: 1, weigth: 0.8, probability: 0.6 });

            blueSphere.animate('blend');  // 'blend' 'priority' 'probability'  'truncated' 
            
            obstacleIstances.forEach(e => {
                    e.animate();
            });

            scene.render();
        });
});

Demo

# 1) istall dependencies
npm install
# 2) run the development server serving static demo pages at localhost:4000
npm start

# only demo page for seek, flee, avoid and hide are available....

Bugs

• wander, avoid and flock are still work in progress!
• Let me know!

Built With

ES6 Javascript, microbundle, Babylon.js

License

This project is licensed under the ISC License.