Merge branch 'develop' into bugfix/npm-install

package.json

@@ -45,7 +45,7 @@
     "scratch-audio": "latest",
     "scratch-blocks": "latest",
     "scratch-render": "latest",
-    "scratch-storage": "^0.1.0",
+    "scratch-storage": "^0.2.0",
     "script-loader": "0.7.0",
     "socket.io-client": "1.7.3",
     "stats.js": "^0.17.0",

src/blocks/scratch3_control.js

@@ -1,5 +1,4 @@
 const Cast = require('../util/cast');
-const Timer = require('../util/timer');
 
 class Scratch3ControlBlocks {
     constructor (runtime) {
@@ -73,18 +72,13 @@ class Scratch3ControlBlocks {
         util.startBranch(1, true);
     }
 
-    wait (args, util) {
+    wait (args) {
-        if (!util.stackFrame.timer) {
+        const duration = Math.max(0, 1000 * Cast.toNumber(args.DURATION));
-            util.stackFrame.timer = new Timer();
+        return new Promise(resolve => {
-            util.stackFrame.timer.start();
+            setTimeout(() => {
-            util.yield();
+                resolve();
-            this.runtime.requestRedraw();
+            }, duration);
-        } else {
+        });
-            const duration = Math.max(0, 1000 * Cast.toNumber(args.DURATION));
-            if (util.stackFrame.timer.timeElapsed() < duration) {
-                util.yield();
-            }
-        }
     }
 
     if (args, util) {

src/blocks/scratch3_wedo2.js

@@ -0,0 +1,700 @@
+const color = require('../util/color');
+const log = require('../util/log');
+
+/**
+ * Manage power, direction, and timers for one WeDo 2.0 motor.
+ */
+class WeDo2Motor {
+    /**
+     * Construct a WeDo2Motor instance.
+     * @param {WeDo2} parent - the WeDo 2.0 device which owns this motor.
+     * @param {int} index - the zero-based index of this motor on its parent device.
+     */
+    constructor (parent, index) {
+        /**
+         * The WeDo 2.0 device which owns this motor.
+         * @type {WeDo2}
+         * @private
+         */
+        this._parent = parent;
+
+        /**
+         * The zero-based index of this motor on its parent device.
+         * @type {int}
+         * @private
+         */
+        this._index = index;
+
+        /**
+         * This motor's current direction: 1 for "this way" or -1 for "that way"
+         * @type {number}
+         * @private
+         */
+        this._direction = 1;
+
+        /**
+         * This motor's current power level, in the range [0,100].
+         * @type {number}
+         * @private
+         */
+        this._power = 100;
+
+        /**
+         * Is this motor currently moving?
+         * @type {boolean}
+         * @private
+         */
+        this._isOn = false;
+
+        /**
+         * If the motor has been turned on or is actively braking for a specific duration, this is the timeout ID for
+         * the end-of-action handler. Cancel this when changing plans.
+         * @type {Object}
+         * @private
+         */
+        this._pendingTimeoutId = null;
+
+        this.startBraking = this.startBraking.bind(this);
+        this.setMotorOff = this.setMotorOff.bind(this);
+    }
+
+    /**
+     * @return {number} - the duration of active braking after a call to startBraking(). Afterward, turn the motor off.
+     * @constructor
+     */
+    static get BRAKE_TIME_MS () {
+        return 1000;
+    }
+
+    /**
+     * @return {int} - this motor's current direction: 1 for "this way" or -1 for "that way"
+     */
+    get direction () {
+        return this._direction;
+    }
+
+    /**
+     * @param {int} value - this motor's new direction: 1 for "this way" or -1 for "that way"
+     */
+    set direction (value) {
+        if (value < 0) {
+            this._direction = -1;
+        } else {
+            this._direction = 1;
+        }
+    }
+
+    /**
+     * @return {int} - this motor's current power level, in the range [0,100].
+     */
+    get power () {
+        return this._power;
+    }
+
+    /**
+     * @param {int} value - this motor's new power level, in the range [0,100].
+     */
+    set power (value) {
+        this._power = Math.max(0, Math.min(value, 100));
+    }
+
+    /**
+     * @return {boolean} - true if this motor is currently moving, false if this motor is off or braking.
+     */
+    get isOn () {
+        return this._isOn;
+    }
+
+    /**
+     * Turn this motor on indefinitely.
+     */
+    setMotorOn () {
+        this._parent._send('motorOn', {motorIndex: this._index, power: this._direction * this._power});
+        this._isOn = true;
+        this._clearTimeout();
+    }
+
+    /**
+     * Turn this motor on for a specific duration.
+     * @param {number} milliseconds - run the motor for this long.
+     */
+    setMotorOnFor (milliseconds) {
+        milliseconds = Math.max(0, milliseconds);
+        this.setMotorOn();
+        this._setNewTimeout(this.startBraking, milliseconds);
+    }
+
+    /**
+     * Start active braking on this motor. After a short time, the motor will turn off.
+     */
+    startBraking () {
+        this._parent._send('motorBrake', {motorIndex: this._index});
+        this._isOn = false;
+        this._setNewTimeout(this.setMotorOff, WeDo2Motor.BRAKE_TIME_MS);
+    }
+
+    /**
+     * Turn this motor off.
+     */
+    setMotorOff () {
+        this._parent._send('motorOff', {motorIndex: this._index});
+        this._isOn = false;
+    }
+
+    /**
+     * Clear the motor action timeout, if any. Safe to call even when there is no pending timeout.
+     * @private
+     */
+    _clearTimeout () {
+        if (this._pendingTimeoutId !== null) {
+            clearTimeout(this._pendingTimeoutId);
+            this._pendingTimeoutId = null;
+        }
+    }
+
+    /**
+     * Set a new motor action timeout, after clearing an existing one if necessary.
+     * @param {Function} callback - to be called at the end of the timeout.
+     * @param {int} delay - wait this many milliseconds before calling the callback.
+     * @private
+     */
+    _setNewTimeout (callback, delay) {
+        this._clearTimeout();
+        const timeoutID = setTimeout(() => {
+            if (this._pendingTimeoutId === timeoutID) {
+                this._pendingTimeoutId = null;
+            }
+            callback();
+        }, delay);
+        this._pendingTimeoutId = timeoutID;
+    }
+}
+
+/**
+ * Manage communication with a WeDo 2.0 device over a Device Manager client socket.
+ */
+class WeDo2 {
+
+    /**
+     * @return {string} - the type of Device Manager device socket that this class will handle.
+     */
+    static get DEVICE_TYPE () {
+        return 'wedo2';
+    }
+
+    /**
+     * Construct a WeDo2 communication object.
+     * @param {Socket} socket - the socket for a WeDo 2.0 device, as provided by a Device Manager client.
+     */
+    constructor (socket) {
+        /**
+         * The socket-IO socket used to communicate with the Device Manager about this device.
+         * @type {Socket}
+         * @private
+         */
+        this._socket = socket;
+
+        /**
+         * The motors which this WeDo 2.0 could possibly have.
+         * @type {[WeDo2Motor]}
+         * @private
+         */
+        this._motors = [new WeDo2Motor(this, 0), new WeDo2Motor(this, 1)];
+
+        /**
+         * The most recently received value for each sensor.
+         * @type {Object.<string, number>}
+         * @private
+         */
+        this._sensors = {
+            tiltX: 0,
+            tiltY: 0,
+            distance: 0
+        };
+
+        this._onSensorChanged = this._onSensorChanged.bind(this);
+        this._onDisconnect = this._onDisconnect.bind(this);
+
+        this._connectEvents();
+    }
+
+    /**
+     * Manually dispose of this object.
+     */
+    dispose () {
+        this._disconnectEvents();
+    }
+
+    /**
+     * @return {number} - the latest value received for the tilt sensor's tilt about the X axis.
+     */
+    get tiltX () {
+        return this._sensors.tiltX;
+    }
+
+    /**
+     * @return {number} - the latest value received for the tilt sensor's tilt about the Y axis.
+     */
+    get tiltY () {
+        return this._sensors.tiltY;
+    }
+
+    /**
+     * @return {number} - the latest value received from the distance sensor.
+     */
+    get distance () {
+        return this._sensors.distance;
+    }
+
+    /**
+     * Access a particular motor on this device.
+     * @param {int} index - the zero-based index of the desired motor.
+     * @return {WeDo2Motor} - the WeDo2Motor instance, if any, at that index.
+     */
+    motor (index) {
+        return this._motors[index];
+    }
+
+    /**
+     * Set the WeDo 2.0 hub's LED to a specific color.
+     * @param {int} rgb - a 24-bit RGB color in 0xRRGGBB format.
+     */
+    setLED (rgb) {
+        this._send('setLED', {rgb});
+    }
+
+    /**
+     * Play a tone from the WeDo 2.0 hub for a specific amount of time.
+     * @param {int} tone - the pitch of the tone, in Hz.
+     * @param {int} milliseconds - the duration of the note, in milliseconds.
+     */
+    playTone (tone, milliseconds) {
+        this._send('playTone', {tone, ms: milliseconds});
+    }
+
+    /**
+     * Stop the tone playing from the WeDo 2.0 hub, if any.
+     */
+    stopTone () {
+        this._send('stopTone');
+    }
+
+    /**
+     * Attach event handlers to the device socket.
+     * @private
+     */
+    _connectEvents () {
+        this._socket.on('sensorChanged', this._onSensorChanged);
+        this._socket.on('deviceWasClosed', this._onDisconnect);
+        this._socket.on('disconnect', this._onDisconnect);
+    }
+
+    /**
+     * Detach event handlers from the device socket.
+     * @private
+     */
+    _disconnectEvents () {
+        this._socket.off('sensorChanged', this._onSensorChanged);
+        this._socket.off('deviceWasClosed', this._onDisconnect);
+        this._socket.off('disconnect', this._onDisconnect);
+    }
+
+    /**
+     * Store the sensor value from an incoming 'sensorChanged' event.
+     * @param {object} event - the 'sensorChanged' event.
+     * @property {string} sensorName - the name of the sensor which changed.
+     * @property {number} sensorValue - the new value of the sensor.
+     * @private
+     */
+    _onSensorChanged (event) {
+        this._sensors[event.sensorName] = event.sensorValue;
+    }
+
+    /**
+     * React to device disconnection. May be called more than once.
+     * @private
+     */
+    _onDisconnect () {
+        this._disconnectEvents();
+    }
+
+    /**
+     * Send a message to the device socket.
+     * @param {string} message - the name of the message, such as 'playTone'.
+     * @param {object} [details] - optional additional details for the message, such as tone duration and pitch.
+     * @private
+     */
+    _send (message, details) {
+        this._socket.emit(message, details);
+    }
+}
+
+/**
+ * Enum for motor specification.
+ * @readonly
+ * @enum {string}
+ */
+const MotorID = {
+    DEFAULT: 'motor',
+    A: 'motor A',
+    B: 'motor B',
+    ALL: 'all motors'
+};
+
+/**
+ * Enum for motor direction specification.
+ * @readonly
+ * @enum {string}
+ */
+const MotorDirection = {
+    FORWARD: 'this way',
+    BACKWARD: 'that way',
+    REVERSE: 'reverse'
+};
+
+/**
+ * Enum for tilt sensor direction.
+ * @readonly
+ * @enum {string}
+ */
+const TiltDirection = {
+    UP: 'up',
+    DOWN: 'down',
+    LEFT: 'left',
+    RIGHT: 'right',
+    ANY: 'any'
+};
+
+/**
+ * Scratch 3.0 blocks to interact with a LEGO WeDo 2.0 device.
+ */
+class Scratch3WeDo2Blocks {
+
+    /**
+     * @return {string} - the name of this extension.
+     */
+    static get EXTENSION_NAME () {
+        return 'wedo2';
+    }
+
+    /**
+     * @return {number} - the tilt sensor counts as "tilted" if its tilt angle meets or exceeds this threshold.
+     */
+    static get TILT_THRESHOLD () {
+        return 15;
+    }
+
+    /**
+     * Construct a set of WeDo 2.0 blocks.
+     * @param {Runtime} runtime - the Scratch 3.0 runtime.
+     */
+    constructor (runtime) {
+        /**
+         * The Scratch 3.0 runtime.
+         * @type {Runtime}
+         */
+        this.runtime = runtime;
+
+        this.runtime.HACK_WeDo2Blocks = this;
+    }
+
+    /**
+     * Use the Device Manager client to attempt to connect to a WeDo 2.0 device.
+     */
+    connect () {
+        if (this._device || this._finder) {
+            return;
+        }
+        const deviceManager = this.runtime.ioDevices.deviceManager;
+        const finder = this._finder =
+            deviceManager.searchAndConnect(Scratch3WeDo2Blocks.EXTENSION_NAME, WeDo2.DEVICE_TYPE);
+        this._finder.promise.then(
+            socket => {
+                if (this._finder === finder) {
+                    this._finder = null;
+                    this._device = new WeDo2(socket);
+                } else {
+                    log.warn('Ignoring success from stale WeDo 2.0 connection attempt');
+                }
+            },
+            reason => {
+                if (this._finder === finder) {
+                    this._finder = null;
+                    log.warn(`WeDo 2.0 connection failed: ${reason}`);
+                } else {
+                    log.warn('Ignoring failure from stale WeDo 2.0 connection attempt');
+                }
+            });
+    }
+
+    /**
+     * Retrieve the block primitives implemented by this package.
+     * @return {object.<string, Function>} Mapping of opcode to Function.
+     */
+    getPrimitives () {
+        return {
+            wedo2_motorOnFor: this.motorOnFor,
+            wedo2_motorOn: this.motorOn,
+            wedo2_motorOff: this.motorOff,
+            wedo2_startMotorPower: this.startMotorPower,
+            wedo2_setMotorDirection: this.setMotorDirection,
+            wedo2_setLightHue: this.setLightHue,
+            wedo2_playNoteFor: this.playNoteFor,
+            wedo2_whenDistance: this.whenDistance,
+            wedo2_whenTilted: this.whenTilted,
+            wedo2_getDistance: this.getDistance,
+            wedo2_isTilted: this.isTilted,
+            wedo2_getTiltAngle: this.getTiltAngle
+        };
+    }
+
+    /**
+     * Turn specified motor(s) on for a specified duration.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to activate.
+     * @property {int} DURATION - the amount of time to run the motors.
+     * @return {Promise} - a promise which will resolve at the end of the duration.
+     */
+    motorOnFor (args) {
+        const durationMS = args.DURATION * 1000;
+        return new Promise(resolve => {
+            this._forEachMotor(args.MOTOR_ID, motorIndex => {
+                this._device.motor(motorIndex).setMotorOnFor(durationMS);
+            });
+
+            // Ensure this block runs for a fixed amount of time even when no device is connected.
+            setTimeout(resolve, durationMS);
+        });
+    }
+
+    /**
+     * Turn specified motor(s) on indefinitely.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to activate.
+     */
+    motorOn (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            this._device.motor(motorIndex).setMotorOn();
+        });
+    }
+
+    /**
+     * Turn specified motor(s) off.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to deactivate.
+     */
+    motorOff (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            this._device.motor(motorIndex).setMotorOff();
+        });
+    }
+
+    /**
+     * Turn specified motor(s) off.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to be affected.
+     * @property {int} POWER - the new power level for the motor(s).
+     */
+    startMotorPower (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            const motor = this._device.motor(motorIndex);
+            motor.power = args.POWER;
+            motor.setMotorOn();
+        });
+    }
+
+    /**
+     * Set the direction of rotation for specified motor(s).
+     * If the direction is 'reverse' the motor(s) will be reversed individually.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to be affected.
+     * @property {MotorDirection} DIRECTION - the new direction for the motor(s).
+     */
+    setMotorDirection (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            const motor = this._device.motor(motorIndex);
+            switch (args.DIRECTION) {
+            case MotorDirection.FORWARD:
+                motor.direction = 1;
+                break;
+            case MotorDirection.BACKWARD:
+                motor.direction = -1;
+                break;
+            case MotorDirection.REVERSE:
+                motor.direction = -motor.direction;
+                break;
+            default:
+                log.warn(`Unknown motor direction in setMotorDirection: ${args.DIRECTION}`);
+                break;
+            }
+        });
+    }
+
+    /**
+     * Set the LED's hue.
+     * @param {object} args - the block's arguments.
+     * @property {number} HUE - the hue to set, in the range [0,100].
+     */
+    setLightHue (args) {
+        // Convert from [0,100] to [0,360]
+        const hue = args.HUE * 360 / 100;
+
+        const rgbObject = color.hsvToRgb({h: hue, s: 1, v: 1});
+
+        const rgbDecimal = color.rgbToDecimal(rgbObject);
+
+        this._device.setLED(rgbDecimal);
+    }
+
+    /**
+     * Make the WeDo 2.0 hub play a MIDI note for the specified duration.
+     * @param {object} args - the block's arguments.
+     * @property {number} NOTE - the MIDI note to play.
+     * @property {number} DURATION - the duration of the note, in seconds.
+     * @return {Promise} - a promise which will resolve at the end of the duration.
+     */
+    playNoteFor (args) {
+        return new Promise(resolve => {
+            const durationMS = args.DURATION * 1000;
+            const tone = this._noteToTone(args.NOTE);
+            this._device.playTone(tone, durationMS);
+
+            // Ensure this block runs for a fixed amount of time even when no device is connected.
+            setTimeout(resolve, durationMS);
+        });
+    }
+
+    /**
+     * Compare the distance sensor's value to a reference.
+     * @param {object} args - the block's arguments.
+     * @property {string} OP - the comparison operation: '<' or '>'.
+     * @property {number} REFERENCE - the value to compare against.
+     * @return {boolean} - the result of the comparison, or false on error.
+     */
+    whenDistance (args) {
+        switch (args.OP) {
+        case '<':
+            return this._device.distance < args.REFERENCE;
+        case '>':
+            return this._device.distance > args.REFERENCE;
+        default:
+            log.warn(`Unknown comparison operator in whenDistance: ${args.OP}`);
+            return false;
+        }
+    }
+
+    /**
+     * Test whether the tilt sensor is currently tilted.
+     * @param {object} args - the block's arguments.
+     * @property {TiltDirection} DIRECTION - the tilt direction to test (up, down, left, right, or any).
+     * @return {boolean} - true if the tilt sensor is tilted past a threshold in the specified direction.
+     */
+    whenTilted (args) {
+        return this._isTilted(args.DIRECTION);
+    }
+
+    /**
+     * @return {number} - the distance sensor's value, scaled to the [0,100] range.
+     */
+    getDistance () {
+        return this._device.distance * 10;
+    }
+
+    /**
+     * Test whether the tilt sensor is currently tilted.
+     * @param {object} args - the block's arguments.
+     * @property {TiltDirection} DIRECTION - the tilt direction to test (up, down, left, right, or any).
+     * @return {boolean} - true if the tilt sensor is tilted past a threshold in the specified direction.
+     */
+    isTilted (args) {
+        return this._isTilted(args.DIRECTION);
+    }
+
+    /**
+     * @param {object} args - the block's arguments.
+     * @property {TiltDirection} DIRECTION - the direction (up, down, left, right) to check.
+     * @return {number} - the tilt sensor's angle in the specified direction.
+     * Note that getTiltAngle(up) = -getTiltAngle(down) and getTiltAngle(left) = -getTiltAngle(right).
+     */
+    getTiltAngle (args) {
+        return this._getTiltAngle(args.DIRECTION);
+    }
+
+    /**
+     * Test whether the tilt sensor is currently tilted.
+     * @param {TiltDirection} direction - the tilt direction to test (up, down, left, right, or any).
+     * @return {boolean} - true if the tilt sensor is tilted past a threshold in the specified direction.
+     * @private
+     */
+    _isTilted (direction) {
+        switch (direction) {
+        case TiltDirection.ANY:
+            return (Math.abs(this._device.tiltX) >= Scratch3WeDo2Blocks.TILT_THRESHOLD) ||
+                (Math.abs(this._device.tiltY) >= Scratch3WeDo2Blocks.TILT_THRESHOLD);
+        default:
+            return this._getTiltAngle(direction) >= Scratch3WeDo2Blocks.TILT_THRESHOLD;
+        }
+    }
+
+    /**
+     * @param {TiltDirection} direction - the direction (up, down, left, right) to check.
+     * @return {number} - the tilt sensor's angle in the specified direction.
+     * Note that getTiltAngle(up) = -getTiltAngle(down) and getTiltAngle(left) = -getTiltAngle(right).
+     * @private
+     */
+    _getTiltAngle (direction) {
+        switch (direction) {
+        case TiltDirection.UP:
+            return -this._device.tiltY;
+        case TiltDirection.DOWN:
+            return this._device.tiltY;
+        case TiltDirection.LEFT:
+            return -this._device.tiltX;
+        case TiltDirection.RIGHT:
+            return this._device.tiltX;
+        default:
+            log.warn(`Unknown tilt direction in _getTiltAngle: ${direction}`);
+        }
+    }
+
+    /**
+     * Call a callback for each motor indexed by the provided motor ID.
+     * @param {MotorID} motorID - the ID specifier.
+     * @param {Function} callback - the function to call with the numeric motor index for each motor.
+     * @private
+     */
+    _forEachMotor (motorID, callback) {
+        let motors;
+        switch (motorID) {
+        case MotorID.A:
+            motors = [0];
+            break;
+        case MotorID.B:
+            motors = [1];
+            break;
+        case MotorID.ALL:
+        case MotorID.DEFAULT:
+            motors = [0, 1];
+            break;
+        default:
+            log.warn(`Invalid motor ID: ${motorID}`);
+            motors = [];
+            break;
+        }
+        for (const index of motors) {
+            callback(index);
+        }
+    }
+
+    /**
+     * @param {number} midiNote - the MIDI note value to convert.
+     * @return {number} - the frequency, in Hz, corresponding to that MIDI note value.
+     * @private
+     */
+    _noteToTone (midiNote) {
+        // Note that MIDI note 69 is A4, 440 Hz
+        return 440 * Math.pow(2, (midiNote - 69) / 12);
+    }
+}
+
+module.exports = Scratch3WeDo2Blocks;

src/engine/runtime.js

@@ -20,7 +20,8 @@ const defaultBlockPackages = {
     scratch3_sound: require('../blocks/scratch3_sound'),
     scratch3_sensing: require('../blocks/scratch3_sensing'),
     scratch3_data: require('../blocks/scratch3_data'),
-    scratch3_procedures: require('../blocks/scratch3_procedures')
+    scratch3_procedures: require('../blocks/scratch3_procedures'),
+    scratch3_wedo2: require('../blocks/scratch3_wedo2')
 };
 
 /**

src/import/load-costume.js

@@ -1,3 +1,4 @@
+const StringUtil = require('../util/string-util');
 const log = require('../util/log');
 
 /**
@@ -19,17 +20,17 @@ const loadCostume = function (md5ext, costume, runtime) {
     }
 
     const AssetType = runtime.storage.AssetType;
-    const idParts = md5ext.split('.');
+    const idParts = StringUtil.splitFirst(md5ext, '.');
     const md5 = idParts[0];
-    const ext = idParts[1].toUpperCase();
+    const ext = idParts[1].toLowerCase();
-    const assetType = (ext === 'SVG') ? AssetType.ImageVector : AssetType.ImageBitmap;
+    const assetType = (ext === 'svg') ? AssetType.ImageVector : AssetType.ImageBitmap;
 
     const rotationCenter = [
         costume.rotationCenterX / costume.bitmapResolution,
         costume.rotationCenterY / costume.bitmapResolution
     ];
 
-    let promise = runtime.storage.load(assetType, md5).then(costumeAsset => {
+    let promise = runtime.storage.load(assetType, md5, ext).then(costumeAsset => {
         costume.assetId = costumeAsset.assetId;
         costume.assetType = assetType;
         return costumeAsset;

src/import/load-sound.js

@@ -1,3 +1,4 @@
+const StringUtil = require('../util/string-util');
 const log = require('../util/log');
 
 /**
@@ -17,9 +18,10 @@ const loadSound = function (sound, runtime) {
         log.error('No audio engine present; cannot load sound asset: ', sound.md5);
         return Promise.resolve(sound);
     }
-    const idParts = sound.md5.split('.');
+    const idParts = StringUtil.splitFirst(sound.md5, '.');
     const md5 = idParts[0];
-    return runtime.storage.load(runtime.storage.AssetType.Sound, md5)
+    const ext = idParts[1].toLowerCase();
+    return runtime.storage.load(runtime.storage.AssetType.Sound, md5, ext)
         .then(soundAsset => {
             sound.assetId = soundAsset.assetId;
             sound.assetType = runtime.storage.AssetType.Sound;

src/playground/playground.js

@@ -34,7 +34,7 @@ const getAssetUrl = function (asset) {
         'internalapi/asset/',
         asset.assetId,
         '.',
-        asset.assetType.runtimeFormat,
+        asset.dataFormat,
         '/get/'
     ];
     return assetUrlParts.join('');

src/serialization/sb3.js

@@ -75,7 +75,7 @@ const parseScratchObject = function (object, runtime) {
             rotationCenterX: costumeSource.rotationCenterX,
             rotationCenterY: costumeSource.rotationCenterY
         };
-        const costumeMd5 = `${costumeSource.assetId}.${costumeSource.assetType.runtimeFormat}`;
+        const costumeMd5 = `${costumeSource.assetId}.${costumeSource.dataFormat}`;
         return loadCostume(costumeMd5, costume, runtime);
     });
     // Sounds from JSON

src/sprites/rendered-target.js

@@ -832,6 +832,8 @@ class RenderedTarget extends Target {
      */
     dispose () {
         this.runtime.changeCloneCounter(-1);
+        this.runtime.stopForTarget(this);
+        this.sprite.removeClone(this);
         if (this.renderer && this.drawableID !== null) {
             this.renderer.destroyDrawable(this.drawableID);
             if (this.visible) {

src/sprites/sprite.js

@@ -58,6 +58,18 @@ class Sprite {
         }
         return newClone;
     }
+
+    /**
+     * Disconnect a clone from this sprite. The clone is unmodified.
+     * In particular, the clone's dispose() method is not called.
+     * @param {!RenderedTarget} clone - the clone to be removed.
+     */
+    removeClone (clone) {
+        const cloneIndex = this.clones.indexOf(clone);
+        if (cloneIndex >= 0) {
+            this.clones.splice(cloneIndex, 1);
+        }
+    }
 }
 
 module.exports = Sprite;

src/util/string-util.js

@@ -12,6 +12,30 @@ class StringUtil {
         while (existingNames.indexOf(name + i) >= 0) i++;
         return name + i;
     }
+
+    /**
+     * Split a string on the first occurrence of a split character.
+     * @param {string} text - the string to split.
+     * @param {string} separator - split the text on this character.
+     * @returns {[string, string]} - the two parts of the split string, or [text, null] if no split character found.
+     * @example
+     * // returns ['foo', 'tar.gz']
+     * splitFirst('foo.tar.gz', '.');
+     * @example
+     * // returns ['foo', null]
+     * splitFirst('foo', '.');
+     * @example
+     * // returns ['foo', '']
+     * splitFirst('foo.', '.');
+     */
+    static splitFirst (text, separator) {
+        const index = text.indexOf(separator);
+        if (index >= 0) {
+            return [text.substring(0, index), text.substring(index + 1)];
+        } else {
+            return [text, null];
+        }
+    }
 }
 
 module.exports = StringUtil;

src/virtual-machine.js

@@ -364,6 +364,8 @@ class VirtualMachine extends EventEmitter {
      */
     deleteSprite (targetId) {
         const target = this.runtime.getTargetById(targetId);
+        const targetIndexBeforeDelete = this.runtime.targets.map(t => t.id).indexOf(target.id);
+
         if (target) {
             if (!target.isSprite()) {
                 throw new Error('Cannot delete non-sprite targets.');
@@ -379,7 +381,8 @@ class VirtualMachine extends EventEmitter {
                 this.runtime.disposeTarget(sprite.clones[i]);
                 // Ensure editing target is switched if we are deleting it.
                 if (clone === currentEditingTarget) {
-                    this.setEditingTarget(this.runtime.targets[0].id);
+                    const nextTargetIndex = Math.min(this.runtime.targets.length - 1, targetIndexBeforeDelete);
+                    this.setEditingTarget(this.runtime.targets[nextTargetIndex].id);
                 }
             }
             // Sprite object should be deleted by GC.

test/fixtures/attach-test-storage.js

@@ -26,7 +26,7 @@ const getAssetUrl = function (asset) {
         'internalapi/asset/',
         asset.assetId,
         '.',
-        asset.assetType.runtimeFormat,
+        asset.dataFormat,
         '/get/'
     ];
     return assetUrlParts.join('');

test/integration/clone-cleanup.js

@@ -0,0 +1,96 @@
+const path = require('path');
+const test = require('tap').test;
+const attachTestStorage = require('../fixtures/attach-test-storage');
+const extract = require('../fixtures/extract');
+const VirtualMachine = require('../../src/index');
+
+const projectUri = path.resolve(__dirname, '../fixtures/clone-cleanup.sb2');
+const project = extract(projectUri);
+
+test('clone-cleanup', t => {
+    const vm = new VirtualMachine();
+    attachTestStorage(vm);
+
+    /**
+     * Track which step of the project is currently under test.
+     * @type {number}
+     */
+    let testStep = -1;
+
+    /**
+     * We test using setInterval; track the interval ID here so we can cancel it.
+     * @type {object}
+     */
+    let testInterval = null;
+
+    const verifyCounts = (expectedClones, extraThreads) => {
+        // stage plus one sprite, plus clones
+        t.strictEqual(vm.runtime.targets.length, 2 + expectedClones,
+            `target count at step ${testStep}`);
+
+        // the stage should never have any clones
+        t.strictEqual(vm.runtime.targets[0].sprite.clones.length, 1,
+            `stage clone count at step ${testStep}`);
+
+        // check sprite clone count (+1 for original)
+        t.strictEqual(vm.runtime.targets[1].sprite.clones.length, 1 + expectedClones,
+            `sprite clone count at step ${testStep}`);
+
+        // thread count isn't directly tied to clone count since threads can end
+        t.strictEqual(vm.runtime.threads.length, extraThreads + (2 * expectedClones),
+            `thread count at step ${testStep}`);
+    };
+
+    const testNextStep = () => {
+        ++testStep;
+        switch (testStep) {
+        case 0:
+            // Project has started, main thread running, no clones yet
+            verifyCounts(0, 1);
+            break;
+
+        case 1:
+            // 10 clones have been created, main thread still running
+            verifyCounts(10, 1);
+            break;
+
+        case 2:
+            // The first batch of clones has deleted themselves; main thread still running
+            verifyCounts(0, 1);
+            break;
+
+        case 3:
+            // The second batch of clones has been created and the main thread has ended
+            verifyCounts(10, 0);
+            break;
+
+        case 4:
+            // The second batch of clones has deleted themselves; everything is finished
+            verifyCounts(0, 0);
+
+            clearInterval(testInterval);
+            t.end();
+            process.nextTick(process.exit);
+            break;
+        }
+    };
+
+    // Start VM, load project, and run
+    t.doesNotThrow(() => {
+        vm.start();
+        vm.clear();
+        vm.setCompatibilityMode(false);
+        vm.setTurboMode(false);
+        vm.loadProject(project).then(() => {
+
+            // Verify initial state: no clones, nothing running ("step -1")
+            verifyCounts(0, 0);
+
+            vm.greenFlag();
+
+            // Every second, advance the testing step
+            testInterval = setInterval(testNextStep, 1000);
+        });
+    });
+
+});

test/unit/util_string.js

@@ -1,6 +1,14 @@
 const test = require('tap').test;
 const StringUtil = require('../../src/util/string-util');
 
+test('splitFirst', t => {
+    t.deepEqual(StringUtil.splitFirst('asdf.1234', '.'), ['asdf', '1234']);
+    t.deepEqual(StringUtil.splitFirst('asdf.', '.'), ['asdf', '']);
+    t.deepEqual(StringUtil.splitFirst('.1234', '.'), ['', '1234']);
+    t.deepEqual(StringUtil.splitFirst('foo', '.'), ['foo', null]);
+    t.end();
+});
+
 test('withoutTrailingDigits', t => {
     t.strictEqual(StringUtil.withoutTrailingDigits('boeing747'), 'boeing');
     t.strictEqual(StringUtil.withoutTrailingDigits('boeing747 '), 'boeing747 ');