Philip's gravity example

scripts/tutorials/NBody/gravity.js

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+//  gravity.js
+//
+//  Created by Philip Rosedale on March 29, 2016
+//  Copyright 2016 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
+//
+//  This entity script causes the object to move with gravitational force and be attracted to other spheres nearby.
+//  The force is scaled by GRAVITY_STRENGTH, and only entities of type "Sphere" within GRAVITY_RANGE will affect it.
+//  The person who has most recently grabbed this object will simulate it.
+//
+
+function Timer() {
+    var time;
+    var count = 0;
+    var totalTime = 0;
+    this.reset = function() {
+        count = 0;
+        totalTime = 0;
+    }
+    this.start = function() {
+        time = new Date().getTime();
+    }
+    this.record = function() {
+        var elapsed =  new Date().getTime() - time;
+        totalTime += elapsed;
+        count++;
+        return elapsed;
+    }
+    this.count = function() {
+        return count;
+    }
+    this.average = function() {
+        return (count == 0) ? 0 : totalTime / count;
+    }
+    this.elapsed = function() {
+        return new Date().getTime() - time;
+    }
+}
+
+(function () {
+    var entityID,
+        wantDebug = true,
+        CHECK_INTERVAL = 10.00,
+        SEARCH_INTERVAL = 1000,
+        GRAVITY_RANGE = 20.0,
+        GRAVITY_STRENGTH = 1.0,
+        MIN_VELOCITY = 0.01,
+        timeoutID = null,
+        timeSinceLastSearch = 0,
+        timer = new Timer(),
+        simulate = false,
+        spheres = [];
+
+    var printDebug = function(message) {
+        if (wantDebug) {
+            print(message);
+        }
+    }
+
+    var greatestDimension = function(dimensions) {
+        return Math.max(Math.max(dimensions.x, dimensions.y), dimensions.z);
+    }
+
+    var mass2 = function(dimensions) {
+        return dimensions.x * dimensions.y * dimensions.z;
+    }
+
+    var findSpheres = function(position) {
+        var entities = Entities.findEntities(position, GRAVITY_RANGE);
+        spheres = [];
+        for (var i = 0; i < entities.length; i++) {
+            if (entityID == spheres[i]) {
+                // this entity doesn't experience its own gravity.
+                continue;
+            }
+            var props = Entities.getEntityProperties(entities[i]);
+            if (props && (props.shapeType == "sphere" || props.type == "Sphere")) {
+                spheres.push(entities[i]);
+            }
+        }
+        // print("FOUND " + spheres.length + " SPHERES");
+    }
+
+    var applyGravity = function() {
+        if (!simulate) {
+            return;
+        }
+
+        var properties = Entities.getEntityProperties(entityID);
+        if (!properties || !properties.position) {
+            return;
+        }
+
+        // update the list of nearby spheres
+        var deltaTime = timer.elapsed() / 1000.0;
+        if (deltaTime == 0.0) {
+            return;
+        }
+        timeSinceLastSearch += CHECK_INTERVAL;
+        if (timeSinceLastSearch >= SEARCH_INTERVAL) {
+            findSpheres(properties.position);
+            timeSinceLastSearch = 0;
+        }
+
+        var deltaVelocity = { x: 0, y: 0, z: 0 };
+        var otherCount = 0;
+        var mass = mass2(properties.dimensions);
+
+        for (var i = 0; i < spheres.length; i++) {
+            otherProperties = Entities.getEntityProperties(spheres[i]);
+            if (!otherProperties || !otherProperties.position) {
+                continue; // sphere was deleted
+            }
+            otherCount++;
+            var radius = Vec3.distance(properties.position, otherProperties.position);
+            var otherMass = mass2(otherProperties.dimensions);
+            var r = (greatestDimension(properties.dimensions) + greatestDimension(otherProperties.dimensions)) / 2;
+            if (radius > r) {
+                var n0 = Vec3.normalize(Vec3.subtract(otherProperties.position, properties.position));
+                var n1 = Vec3.multiply(deltaTime * GRAVITY_STRENGTH * otherMass / (radius * radius), n0);
+                deltaVelocity = Vec3.sum(deltaVelocity, n1);
+            }
+        }
+        Entities.editEntity(entityID, { velocity: Vec3.sum(properties.velocity, deltaVelocity) });
+        if (Vec3.length(properties.velocity) < MIN_VELOCITY) {
+            print("Gravity simulation stopped due to velocity");
+            simulate = false;
+        } else {
+            timer.start();
+            timeoutID = Script.setTimeout(applyGravity, CHECK_INTERVAL);
+        }
+    }
+    this.applyGravity = applyGravity;
+
+    var releaseGrab = function() {
+        printDebug("Gravity simulation started.");
+        var properties = Entities.getEntityProperties(entityID);
+        findSpheres(properties.position);
+        timer.start();
+        timeoutID = Script.setTimeout(applyGravity, CHECK_INTERVAL);
+        simulate = true;
+    }
+    this.releaseGrab = releaseGrab;
+
+    var preload = function (givenEntityID) {
+        printDebug("load gravity...");
+        entityID = givenEntityID;
+    };
+    this.preload = preload;
+
+    var unload = function () {
+        printDebug("Unload gravity...");
+        if (timeoutID !== undefined) {
+            Script.clearTimeout(timeoutID);
+        }
+        if (simulate) {
+            Entities.editEntity(entityID, { velocity: { x: 0, y: 0, z: 0 } });
+        }
+    };
+    this.unload = unload;
+
+    var handleMessages = function(channel, message, sender) {
+        if (channel === 'Hifi-Object-Manipulation') {
+            try {
+                var parsedMessage = JSON.parse(message);
+                if (parsedMessage.action === 'grab' && parsedMessage.grabbedEntity == entityID) {
+                    print("Gravity simulation stopped due to grab");
+                    simulate = false;
+                }
+            } catch (e) {
+                print('error parsing Hifi-Object-Manipulation message: ' + message);
+            }
+        }
+    }
+    this.handleMessages = handleMessages;
+
+    Messages.messageReceived.connect(this.handleMessages);
+    Messages.subscribe('Hifi-Object-Manipulation');
+});

scripts/tutorials/NBody/gravity.svg

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+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="64"
+   height="64"
+   viewBox="0 0 64.000001 64.000001"
+   id="svg2"
+   version="1.1"
+   inkscape:version="0.91 r13725"
+   sodipodi:docname="gravity.svg">
+  <defs
+     id="defs4" />
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.0"
+     inkscape:pageshadow="2"
+     inkscape:zoom="1.4"
+     inkscape:cx="192.07838"
+     inkscape:cy="33.619203"
+     inkscape:document-units="px"
+     inkscape:current-layer="layer1"
+     showgrid="false"
+     units="px"
+     inkscape:window-width="2782"
+     inkscape:window-height="1764"
+     inkscape:window-x="98"
+     inkscape:window-y="36"
+     inkscape:window-maximized="1" />
+  <metadata
+     id="metadata7">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1"
+     transform="translate(0,-988.36216)">
+    <ellipse
+       style="fill:#a09898;fill-opacity:1;stroke:#000000;stroke-opacity:1;stroke-width:3;stroke-miterlimit:4;stroke-dasharray:none"
+       id="path4690"
+       cx="12.142858"
+       cy="1039.1478"
+       rx="8.5714283"
+       ry="8.2142859" />
+    <ellipse
+       style="fill:#3131d9;fill-opacity:1;stroke:#000000;stroke-width:3;stroke-opacity:1;stroke-miterlimit:4;stroke-dasharray:none"
+       id="path4692"
+       cx="39.285717"
+       cy="1014.1478"
+       rx="21.358366"
+       ry="21.001223" />
+  </g>
+</svg>

scripts/tutorials/NBody/makePlanets.js

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+//  makePlanets.js
+//
+//  Created by Philip Rosedale on March 29, 2016
+//  Copyright 2016 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
+//
+//  Make an earth and moon, where you can grab and throw moon into orbit.  Entity
+//  script attached to moon gives it gravitation behavior and will also make it attracted to
+//  other spheres placed nearby.
+//
+
+var SCALE = 3.0;
+var EARTH_SIZE = 3.959 / SCALE;
+var MOON_SIZE = 1.079 / SCALE;
+
+var BUTTON_SIZE = 32;
+var PADDING = 3;
+
+var earth = null;
+var moon = null;
+
+var SCRIPT_URL = Script.resolvePath("gravity.js");
+
+HIFI_PUBLIC_BUCKET = "http://s3.amazonaws.com/hifi-public/";
+Script.include(["/~/system/libraries/toolBars.js"]);
+var toolBar = new ToolBar(0, 0, ToolBar.HORIZONTAL, "highfidelity.makePlanets.js");
+
+var makePlanetsIconURL = Script.resolvePath("gravity.svg");
+var button = toolBar.addOverlay("image", {
+    width: BUTTON_SIZE,
+    height: BUTTON_SIZE,
+    imageURL: makePlanetsIconURL,
+    color: {
+        red: 255,
+        green: 255,
+        blue: 255
+    },
+    alpha: 1
+});
+
+var deleteButton = toolBar.addOverlay("image", {
+    width: BUTTON_SIZE,
+    height: BUTTON_SIZE,
+    imageURL: HIFI_PUBLIC_BUCKET + "images/delete.png",
+    color: {
+        red: 255,
+        green: 255,
+        blue: 255
+    },
+    alpha: 1
+});
+
+function inFrontOfMe(distance) {
+    return Vec3.sum(Camera.getPosition(), Vec3.multiply(distance, Quat.getFront(Camera.getOrientation())));
+}
+
+function onButtonClick() {
+    earth = Entities.addEntity({
+        type: "Model",
+        name: "Earth",
+        modelURL: Script.resolvePath("earth.fbx"),
+        position: inFrontOfMe(2 * EARTH_SIZE),
+        dimensions: { x: EARTH_SIZE, y: EARTH_SIZE, z: EARTH_SIZE },
+        shapeType: "sphere",
+        lifetime: 86400, // 1 day
+        angularDamping: 0,
+        angularVelocity: { x: 0, y: 0.1, z: 0 },
+    });
+    moon = Entities.addEntity({
+        type: "Model",
+        name: "Moon",
+        modelURL: Script.resolvePath("moon.fbx"),
+        position: inFrontOfMe(EARTH_SIZE - MOON_SIZE),
+        dimensions: { x: MOON_SIZE, y: MOON_SIZE, z: MOON_SIZE },
+        dynamic: true,
+        damping: 0, // 0.01,
+        angularDamping: 0, // 0.01,
+        script: SCRIPT_URL,
+        shapeType: "sphere"
+    });
+    Entities.addEntity({
+        "accelerationSpread": {
+            "x": 0,
+            "y": 0,
+            "z": 0
+        },
+        "alpha": 1,
+        "alphaFinish": 0,
+        "alphaStart": 1,
+        "azimuthFinish": 0,
+        "azimuthStart": 0,
+        "color": {
+            "blue": 255,
+            "green": 255,
+            "red": 255
+        },
+        "colorFinish": {
+            "blue": 255,
+            "green": 255,
+            "red": 255
+        },
+        "colorStart": {
+            "blue": 255,
+            "green": 255,
+            "red": 255
+        },
+        "dimensions": {
+            "x": 0.10890001058578491,
+            "y": 0.10890001058578491,
+            "z": 0.10890001058578491
+        },
+        "emitAcceleration": {
+            "x": 0,
+            "y": 0,
+            "z": 0
+        },
+        "emitOrientation": {
+            "w": 0.99999994039535522,
+            "x": 0,
+            "y": 0,
+            "z": 0
+        },
+        "emitRate": 300,
+        "emitSpeed": 0,
+        "emitterShouldTrail": 1,
+        "maxParticles": 10000,
+        "name": "moon trail",
+        "parentID": moon,
+        "particleRadius": 0.005,
+        "radiusFinish": 0.005,
+        "radiusSpread": 0.005,
+        "radiusStart": 0.005,
+        "speedSpread": 0,
+        "lifespan": 20,
+        "textures": "https://hifi-public.s3.amazonaws.com/alan/Particles/Particle-Sprite-Smoke-1.png",
+        "type": "ParticleEffect",
+        "userData": "{\"grabbableKey\":{\"grabbable\":false}}"
+    });
+}
+
+function onDeleteButton() {
+	Entities.deleteEntity(earth);
+	Entities.deleteEntity(moon);
+}
+
+function mousePressEvent(event) {
+  var clickedText = false;
+  var clickedOverlay = Overlays.getOverlayAtPoint({
+    x: event.x,
+    y: event.y
+  });
+  if (clickedOverlay == button) {
+    onButtonClick();
+  } else if (clickedOverlay == deleteButton) {
+  	onDeleteButton();
+  }
+}
+
+function scriptEnding() {
+  toolBar.cleanup();
+}
+
+Controller.mousePressEvent.connect(mousePressEvent);
+Script.scriptEnding.connect(scriptEnding);