overte-HifiExperiments/scripts/tutorials/entity_scripts/magneticBlock.js

//
//  magneticBlock.js
//
//  Created by Matti Lahtinen 4/3/2017
//  Copyright 2017 High Fidelity, Inc.
//
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
//  Makes the entity the script is bound to connect to nearby, similarly sized entities, like a magnet.

(function() {
    const SNAPSOUND_SOURCE = SoundCache.getSound(Script.resolvePath("../../system/assets/sounds/entitySnap.wav?xrs"));
    // Preload trick for faster playback
    const RANGE_MULTIPLER = 1.5;

    // Helper for detecting nearby objects
    function findEntitiesInRange(releasedProperties) {
        var dimensions = releasedProperties.dimensions;
        return Entities.findEntities(releasedProperties.position, ((dimensions.x + dimensions.y + dimensions.z) / 3) * RANGE_MULTIPLER);
    }

    function getNearestValidEntityProperties(releasedProperties) {
        var entities = findEntitiesInRange(releasedProperties);
        var nearestEntity = null;
        var nearest = 9999999999999;
        var releaseSize = Vec3.length(releasedProperties.dimensions);
        entities.forEach(function(entityId) {
            if (entityId !== releasedProperties.id) {
                var entity = Entities.getEntityProperties(entityId, ['position', 'rotation', 'dimensions']);
                var distance = Vec3.distance(releasedProperties.position, entity.position);
                var scale = releaseSize / Vec3.length(entity.dimensions);

                if (distance < nearest && (scale >= 0.5 && scale <= 2)) {
                    nearestEntity = entity;
                    nearest = distance;
                }
            }
        })
        return nearestEntity;
    }
    // Create the 'class'
    function MagneticBlock() {}
    // Bind pre-emptive events
    MagneticBlock.prototype = {
        // When script is bound to an entity, preload is the first callback called with the entityID. It will behave as the constructor
        preload: function(id) {
            /*
              We will now override any existing userdata with the grabbable property.
              Only retrieving userData
            */
            var val = Entities.getEntityProperties(id, ['userData'])
            var userData = {grabbableKey: {}};

            if (val.userData && val.userData.length > 0) {
                try {
                    userData = JSON.parse(val.userData);
                } catch (e) {
                }
            }
            // Object must be triggerable inorder to bind events.
            userData.grabbableKey.grabbable = true;

            // Apply the new properties to entity of id
            Entities.editEntity(id, {
                userData: JSON.stringify(userData)
            });
            this.held = false;
            // We will now create a custom binding, to keep the 'current' context as these are callbacks called without context
            var t = this;
            this.callbacks = {};
            this.releaseGrab = function() {
                var released = Entities.getEntityProperties(id, ["position", "rotation", "dimensions"]);
                var target = getNearestValidEntityProperties(released);
                if (target !== null) {
                    // We found nearest, now lets do the snap calculations
                    // Plays the snap sound between the two objects.
                    Audio.playSound(SNAPSOUND_SOURCE, {
                        volume: 1,
                        position: Vec3.mix(target.position, released.position, 0.5)
                    });
                    // Check Nearest Axis
                    var difference = Vec3.subtract(released.position, target.position);
                    var relativeDifference = Vec3.multiplyQbyV(Quat.inverse(target.rotation), difference);

                    var abs = {
                        x: Math.abs(relativeDifference.x),
                        y: Math.abs(relativeDifference.y),
                        z: Math.abs(relativeDifference.z)
                    };
                    // Check what value is greater. Simplified.
                    if (abs.x >= abs.y && abs.x >= abs.z) {
                        relativeDifference.y = 0;
                        relativeDifference.z = 0;
                        if (relativeDifference.x > 0) {
                            relativeDifference.x = target.dimensions.x / 2 + released.dimensions.x / 2;
                        } else {
                            relativeDifference.x = -target.dimensions.x / 2 - released.dimensions.x / 2;
                        }
                    } else if (abs.y >= abs.x && abs.y >= abs.z) {
                        relativeDifference.x = 0;
                        relativeDifference.z = 0;
                        if (relativeDifference.y > 0) {
                            relativeDifference.y = target.dimensions.y / 2 + released.dimensions.y / 2;
                        } else {
                            relativeDifference.y = -target.dimensions.y / 2 - released.dimensions.y / 2;
                        }
                    } else if (abs.z >= abs.x && abs.z >= abs.y) {
                        relativeDifference.x = 0;
                        relativeDifference.y = 0;
                        if (relativeDifference.z > 0) {
                            relativeDifference.z = target.dimensions.z / 2 + released.dimensions.z / 2;
                        } else {
                            relativeDifference.z = -target.dimensions.z / 2 - released.dimensions.z / 2;
                        }
                    }
                    // Can be expanded upon to work in nearest rotation as well, but was not in spec.
                    var newPosition = Vec3.multiplyQbyV(target.rotation, relativeDifference);
                    Entities.editEntity(id, {
                        rotation: target.rotation,
                        position: Vec3.sum(target.position, newPosition)
                    })
                }
            }

            Script.scriptEnding.connect(function() {
                Script.removeEventHandler(id, "releaseGrab", this.releaseGrab);
            })
        }
    }
    return new MagneticBlock();
})