ratSteer.js

//
//  ratSteer.js
//
//  Created by James B. Pollack @imgntn on 12/7/2015
//  Copyright 2015 High Fidelity, Inc.
//
//  This is an example of steering behaviors that can be applied entities.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//

function flee(thisEntity, target) {
    var targetPosition = Entities.getEntityProperties(target, "position").position;
    var properties = Entities.getEntityProperties(thisEntity, ["position", "velocity"]);
    var location = properties.position;
    var velocity = properties.velocity;
    var MAX_SPEED = 1;
    var MAX_FORCE = 1;
    var FLEE_RANGE = 2;
    var desired = Vec3.subtract(location, targetPosition);
    var d = Vec3.length(desired);
    desired = Vec3.normalize(desired);
    desired = Vec3.multiply(MAX_SPEED, desired);
    if (d < FLEE_RANGE) {
        var steer = Vec3.subtract(desired, velocity);

        var steerVector = new V3(desired.x, 0, desired.z);
        steer = steerVector.limit(MAX_FORCE);

        return steer;
    } else {
        //target too far away to flee
        return
    }
}

function fleeAllAvatars(thisEntity) {
    //print('FLEE AVATARS');
    var properties = Entities.getEntityProperties(thisEntity, ["position", "velocity"]);
    var location = properties.position;
    var velocity = properties.velocity;

    var nearbyEntities = Entities.findEntities(location, 3);
    var flightVectors = [];
    for (var entityIndex = 0; entityIndex < nearbyEntities.length; entityIndex++) {
        var entityID = nearbyEntities[entityIndex];
        var entityProps = Entities.getEntityProperties(entityID);
        if (entityProps.name === 'Hifi-Avatar-Detector') {
            //found an avatar to flee

            var MAX_SPEED = 8;
            var MAX_FORCE = 8;
            var FLEE_AVATAR_RANGE = 3;
            var desired = Vec3.subtract(location, entityProps.position);
            var d = Vec3.length(desired);
            desired = Vec3.normalize(desired);
            desired = Vec3.multiply(MAX_SPEED, desired);
            if (d < FLEE_AVATAR_RANGE) {
                var steer = Vec3.subtract(desired, velocity);
                var steerVector = new V3(desired.x, 0, desired.z);
                steer = steerVector.limit(MAX_FORCE);
                flightVectors.push(steer);
            } else {
                // target too far away from this avatar to flee
            }
        }

    }

    return flightVectors;
}

function fleeAvoiderBlocks(thisEntity) {
    // print('FLEE AVOIDER BLOCKS');
    var properties = Entities.getEntityProperties(thisEntity, ["position", "velocity"]);
    var location = properties.position;
    var velocity = properties.velocity;

    var nearbyEntities = Entities.findEntities(location, 2);
    var flightVectors = [];
    for (var entityIndex = 0; entityIndex < nearbyEntities.length; entityIndex++) {
        var entityID = nearbyEntities[entityIndex];
        var entityProps = Entities.getEntityProperties(entityID);
        if (entityProps.name === 'Hifi-Rat-Avoider') {
            //found an avoiderblock to flee

            var MAX_SPEED = 11;
            var MAX_FORCE = 6;
            var FLEE_AVOIDER_RANGE = 5;

            var desired = Vec3.subtract(location, entityProps.position);
            var d = Vec3.length(desired);
            desired = Vec3.normalize(desired);
            desired = Vec3.multiply(MAX_SPEED, desired);

            if (d < FLEE_AVOIDER_RANGE) {
                var steer = Vec3.subtract(desired, velocity);
                var steerVector = new V3(desired.x, 0, desired.z);
                steer = steerVector.limit(MAX_FORCE);
                flightVectors.push(steer);
            } else {
                //target too far away from this avoider to flee
            }

        }

    }

    return flightVectors;
}

function arrive(thisEntity, target) {

    var targetPosition = Entities.getEntityProperties(target, "position").position;
    var properties = Entities.getEntityProperties(thisEntity, ["position", "velocity"]);
    var location = properties.position;
    var velocity = properties.velocity;
    var MAX_SPEED = 10;
    var MAX_FORCE = 6;
    var ARRIVAL_DISTANCE = 2;

    var desired = Vec3.subtract(targetPosition, location);
    var d = Vec3.length(desired);
    desired = Vec3.normalize(desired);

    if (d < ARRIVAL_DISTANCE) {
        var m = scale(d, 0, ARRIVAL_DISTANCE, 0, MAX_SPEED);
    } else {
        desired = Vec3.multiply(MAX_SPEED, desired);

    }

    var steer = Vec3.subtract(desired, velocity);
    var steerVector = new V3(desired.x, 0, desired.z);
    steer = steerVector.limit(MAX_FORCE);

    return steer;
}


function V3(x, y, z) {
    this.x = x;
    this.y = y;
    this.z = z;
    return
}

V3.prototype.length = function() {
    return Math.sqrt(this.x * this.x + this.y * this.y + this.z * this.z);
};

V3.prototype.limit = function(s) {
    var len = this.length();

    if (len > s && len > 0) {
        this.scale(s / len);
    }

    return this;
};

V3.prototype.scale = function(f) {
    this.x *= f;
    this.y *= f;
    this.z *= f;
    return this;
};

var v3 = new V3();

var scale = function(value, min1, max1, min2, max2) {
    return min2 + (max2 - min2) * ((value - min1) / (max1 - min1));
}

loadSteer = function() {
    return {
        flee: flee,
        fleeAllAvatars: fleeAllAvatars,
        fleeAvoiderBlocks: fleeAvoiderBlocks,
        arrive: arrive
    };
}