Disable wobbles on Edge

Revert "Revert "Make sprites wobbly when dragged""

package-lock.json

@@ -4860,27 +4860,27 @@
       "dev": true
     },
     "falafel": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/falafel/-/falafel-2.1.0.tgz",
-      "integrity": "sha1-lrsXdh2rqU9G0AFzizzt86Z/4Gw=",
+      "version": "2.2.4",
+      "resolved": "https://registry.npmjs.org/falafel/-/falafel-2.2.4.tgz",
+      "integrity": "sha512-0HXjo8XASWRmsS0X1EkhwEMZaD3Qvp7FfURwjLKjG1ghfRm/MGZl2r4cWUTv41KdNghTw4OUMmVtdGQp3+H+uQ==",
       "dev": true,
       "requires": {
-        "acorn": "^5.0.0",
+        "acorn": "^7.1.1",
         "foreach": "^2.0.5",
-        "isarray": "0.0.1",
+        "isarray": "^2.0.1",
         "object-keys": "^1.0.6"
       },
       "dependencies": {
         "acorn": {
-          "version": "5.7.3",
-          "resolved": "https://registry.npmjs.org/acorn/-/acorn-5.7.3.tgz",
-          "integrity": "sha512-T/zvzYRfbVojPWahDsE5evJdHb3oJoQfFbsrKM7w5Zcs++Tr257tia3BmMP8XYVjp1S9RZXQMh7gao96BlqZOw==",
+          "version": "7.1.1",
+          "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.1.1.tgz",
+          "integrity": "sha512-add7dgA5ppRPxCFJoAGfMDi7PIBXq1RtGo7BhbLaxwrXPOmw8gq48Y9ozT01hUKy9byMjlR20EJhu5zlkErEkg==",
           "dev": true
         },
         "isarray": {
-          "version": "0.0.1",
-          "resolved": "https://registry.npmjs.org/isarray/-/isarray-0.0.1.tgz",
-          "integrity": "sha1-ihis/Kmo9Bd+Cav8YDiTmwXR7t8=",
+          "version": "2.0.5",
+          "resolved": "https://registry.npmjs.org/isarray/-/isarray-2.0.5.tgz",
+          "integrity": "sha512-xHjhDr3cNBK0BzdUJSPXZntQUx/mwMS5Rw4A7lPJ90XGAO6ISP/ePDNuo0vhqOZU+UD5JoodwCAAoZQd3FeAKw==",
           "dev": true
         }
       }
@@ -10649,9 +10649,9 @@
       },
       "dependencies": {
         "minimist": {
-          "version": "1.2.0",
-          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.0.tgz",
-          "integrity": "sha1-o1AIsg9BOD7sH7kU9M1d95omQoQ=",
+          "version": "1.2.5",
+          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
+          "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
           "dev": true
         }
       }
@@ -11549,9 +11549,9 @@
       }
     },
     "scratch-blocks": {
-      "version": "0.1.0-prerelease.1585138708",
-      "resolved": "https://registry.npmjs.org/scratch-blocks/-/scratch-blocks-0.1.0-prerelease.1585138708.tgz",
-      "integrity": "sha512-36UhpFoqVZg79nvZi9lxn0nmZ5hOQqIyIELMmogfwMl5CsRE4HfcjiLizDY/ORm6H5zH/AS1SFmiG78YNCnN+A==",
+      "version": "0.1.0-prerelease.1585323236",
+      "resolved": "https://registry.npmjs.org/scratch-blocks/-/scratch-blocks-0.1.0-prerelease.1585323236.tgz",
+      "integrity": "sha512-iiadFomOLeKX+AU/cwBKTq0X/82zr/d+TcOorEpE0xiIfhztKV+cE5EiQA+eMfpQYZs8XBjojgAgs8Ob+zPuRw==",
       "dev": true,
       "requires": {
         "exports-loader": "0.6.3",
@@ -11686,9 +11686,9 @@
       }
     },
     "scratch-render": {
-      "version": "0.1.0-prerelease.20200228152431",
-      "resolved": "https://registry.npmjs.org/scratch-render/-/scratch-render-0.1.0-prerelease.20200228152431.tgz",
-      "integrity": "sha512-rI/IVwzAHVhq6IoFOgsqwwwwl9acizjJBVxOHKyP9F+/vs34uhbxr+mVUdpO82tSWpjDR+xuw3XfF7oH9U6WnQ==",
+      "version": "0.1.0-prerelease.20200324022200",
+      "resolved": "https://registry.npmjs.org/scratch-render/-/scratch-render-0.1.0-prerelease.20200324022200.tgz",
+      "integrity": "sha512-nW77KkYJa6YG9ytTs6v+DJ1cy6fc+E1B5Jm+K4735VTsrz3eej/APS0QuXx/TdcD29gJryOGkfAcAF4UkBq4lw==",
       "dev": true,
       "requires": {
         "grapheme-breaker": "0.3.2",
@@ -11773,9 +11773,9 @@
       "dev": true
     },
     "scratch-vm": {
-      "version": "0.2.0-prerelease.20200319175700",
-      "resolved": "https://registry.npmjs.org/scratch-vm/-/scratch-vm-0.2.0-prerelease.20200319175700.tgz",
-      "integrity": "sha512-CSCGU3XJhq68kw+74Nsdj3Bfo4D0jsGumh3DocLQCDbltrpvfEDfAMHwkFwetdCE8/XO+oHY/FdI4Joy7OimwA==",
+      "version": "0.2.0-prerelease.20200327113900",
+      "resolved": "https://registry.npmjs.org/scratch-vm/-/scratch-vm-0.2.0-prerelease.20200327113900.tgz",
+      "integrity": "sha512-CjnzBAT3GoP0g9X4QXkW2GP3AFRIoPTLwsR0luiN3VLYp4NOETsZpF+0uXfGzKp03M8lXH+YRsmlhsls8by1Pw==",
       "dev": true,
       "requires": {
         "@vernier/godirect": "1.5.0",
@@ -12493,9 +12493,9 @@
       "dev": true
     },
     "static-eval": {
-      "version": "2.0.3",
-      "resolved": "https://registry.npmjs.org/static-eval/-/static-eval-2.0.3.tgz",
-      "integrity": "sha512-zsxDGucfAh8T339sSKgpFbvg15Fms2IVaJGC+jqp0bVsxhcpM+iMeAI8weNo8dmf4OblgifTBUoyk1vGVtYw2w==",
+      "version": "2.0.5",
+      "resolved": "https://registry.npmjs.org/static-eval/-/static-eval-2.0.5.tgz",
+      "integrity": "sha512-nNbV6LbGtMBgv7e9LFkt5JV8RVlRsyJrphfAt9tOtBBW/SfnzZDf2KnS72an8e434A+9e/BmJuTxeGPvrAK7KA==",
       "dev": true,
       "requires": {
         "escodegen": "^1.11.1"

package.json

@@ -108,13 +108,13 @@
     "redux-throttle": "0.1.1",
     "rimraf": "^2.6.1",
     "scratch-audio": "0.1.0-prerelease.20190925183642",
-    "scratch-blocks": "0.1.0-prerelease.1585138708",
+    "scratch-blocks": "0.1.0-prerelease.1585323236",
     "scratch-l10n": "3.8.20200325112845",
     "scratch-paint": "0.2.0-prerelease.20200213174123",
-    "scratch-render": "0.1.0-prerelease.20200228152431",
+    "scratch-render": "0.1.0-prerelease.20200324022200",
     "scratch-storage": "1.3.2",
     "scratch-svg-renderer": "0.2.0-prerelease.20200205003400",
-    "scratch-vm": "0.2.0-prerelease.20200319175700",
+    "scratch-vm": "0.2.0-prerelease.20200327113900",
     "selenium-webdriver": "3.6.0",
     "startaudiocontext": "1.2.1",
     "style-loader": "^0.23.0",

src/components/gui/gui.jsx

@@ -18,6 +18,7 @@ import StageWrapper from '../../containers/stage-wrapper.jsx';
 import Loader from '../loader/loader.jsx';
 import Box from '../box/box.jsx';
 import MenuBar from '../menu-bar/menu-bar.jsx';
+import MysteryMode from '../mystery-mode/mystery-mode.jsx';
 import CostumeLibrary from '../../containers/costume-library.jsx';
 import BackdropLibrary from '../../containers/backdrop-library.jsx';
 import Watermark from '../../containers/watermark.jsx';
@@ -156,6 +157,7 @@ const GUIComponent = props => {
                 dir={isRtl ? 'rtl' : 'ltr'}
                 {...componentProps}
             >
+                <MysteryMode />
                 {telemetryModalVisible ? (
                     <TelemetryModal
                         onCancel={onTelemetryModalCancel}

src/components/menu-bar/menu-bar.jsx

@@ -32,6 +32,8 @@ import MenuBarHOC from '../../containers/menu-bar-hoc.jsx';
 
 import {openTipsLibrary} from '../../reducers/modals';
 import {setPlayer} from '../../reducers/mode';
+import {toggleMysteryMode} from '../../reducers/mystery-mode';
+import {toggleWobblyDragging} from '../../reducers/wobbly-dragging';
 import {
     autoUpdateProject,
     getIsUpdating,
@@ -74,6 +76,8 @@ import scratchLogo from './scratch-logo.svg';
 
 import sharedMessages from '../../lib/shared-messages';
 
+const isEdge = bowser.msedge;
+
 const ariaMessages = defineMessages({
     language: {
         id: 'gui.menuBar.LanguageSelector',
@@ -469,6 +473,38 @@ class MenuBar extends React.Component {
                                             )}
                                         </MenuItem>
                                     )}</TurboMode>
+                                    <MenuItem onClick={this.props.onClickToggleMysteryMode}>
+                                        {this.props.mysteryMode ? (
+                                            <FormattedMessage
+                                                defaultMessage="Turn off Mystery Mode"
+                                                description="Menu bar item for turning off dark mode"
+                                                id="gui.menuBar.mysteryModeOff"
+                                            />
+                                        ) : (
+                                            <FormattedMessage
+                                                defaultMessage="Turn on Mystery Mode"
+                                                description="Menu bar item for turning on dark mode"
+                                                id="gui.menuBar.mysteryModeOn"
+                                            />
+                                        )}
+                                    </MenuItem>
+                                    {isEdge ? null : (
+                                        <MenuItem onClick={this.props.onClickToggleWobblyDragging}>
+                                            {this.props.wobblyDragging ? (
+                                                <FormattedMessage
+                                                    defaultMessage="Turn off wobbly sprite dragging"
+                                                    description="Menu bar item for turning off wobbly sprite dragging"
+                                                    id="gui.menuBar.wobblyDraggingOff"
+                                                />
+                                            ) : (
+                                                <FormattedMessage
+                                                    defaultMessage="Turn on wobbly sprite dragging"
+                                                    description="Menu bar item for turning on wobbly sprite dragging"
+                                                    id="gui.menuBar.wobblyDraggingOn"
+                                                />
+                                            )}
+                                        </MenuItem>
+                                    )}
                                 </MenuSection>
                             </MenuBarMenu>
                         </div>
@@ -722,6 +758,7 @@ MenuBar.propTypes = {
     locale: PropTypes.string.isRequired,
     loginMenuOpen: PropTypes.bool,
     logo: PropTypes.string,
+    mysteryMode: PropTypes.bool,
     onClickAccount: PropTypes.func,
     onClickEdit: PropTypes.func,
     onClickFile: PropTypes.func,
@@ -732,6 +769,8 @@ MenuBar.propTypes = {
     onClickRemix: PropTypes.func,
     onClickSave: PropTypes.func,
     onClickSaveAsCopy: PropTypes.func,
+    onClickToggleMysteryMode: PropTypes.func,
+    onClickToggleWobblyDragging: PropTypes.func,
     onLogOut: PropTypes.func,
     onOpenRegistration: PropTypes.func,
     onOpenTipLibrary: PropTypes.func,
@@ -751,7 +790,8 @@ MenuBar.propTypes = {
     showComingSoon: PropTypes.bool,
     userOwnsProject: PropTypes.bool,
     username: PropTypes.string,
-    vm: PropTypes.instanceOf(VM).isRequired
+    vm: PropTypes.instanceOf(VM).isRequired,
+    wobblyDragging: PropTypes.bool
 };
 
 MenuBar.defaultProps = {
@@ -772,12 +812,14 @@ const mapStateToProps = (state, ownProps) => {
         languageMenuOpen: languageMenuOpen(state),
         locale: state.locales.locale,
         loginMenuOpen: loginMenuOpen(state),
+        mysteryMode: state.scratchGui.mysteryMode,
         projectTitle: state.scratchGui.projectTitle,
         sessionExists: state.session && typeof state.session.session !== 'undefined',
         username: user ? user.username : null,
         userOwnsProject: ownProps.authorUsername && user &&
             (ownProps.authorUsername === user.username),
-        vm: state.scratchGui.vm
+        vm: state.scratchGui.vm,
+        wobblyDragging: state.scratchGui.wobblyDragging
     };
 };
 
@@ -798,6 +840,8 @@ const mapDispatchToProps = dispatch => ({
     onClickRemix: () => dispatch(remixProject()),
     onClickSave: () => dispatch(manualUpdateProject()),
     onClickSaveAsCopy: () => dispatch(saveProjectAsCopy()),
+    onClickToggleMysteryMode: () => dispatch(toggleMysteryMode()),
+    onClickToggleWobblyDragging: () => dispatch(toggleWobblyDragging()),
     onSeeCommunity: () => dispatch(setPlayer(true))
 });
 

src/components/mystery-mode/mystery-mode.css

@@ -0,0 +1,9 @@
+.mystery-mode {
+    position: absolute;
+    width: 100%;
+    height: 100%;
+    opacity: 0.9;
+    background: transparent url('./mystery.png') center center;
+    z-index: 50;
+    pointer-events: none;
+}

src/components/mystery-mode/mystery-mode.jsx

@@ -0,0 +1,55 @@
+import PropTypes from 'prop-types';
+import React from 'react';
+import bindAll from 'lodash.bindall';
+import styles from './mystery-mode.css';
+import {connect} from 'react-redux';
+
+class MysteryMode extends React.Component {
+    constructor (props) {
+        super(props);
+        bindAll(this, [
+            'handleMouseMove'
+        ]);
+        this.state = {
+            x: window.innerWidth / 2,
+            y: window.innerHeight / 2
+        };
+    }
+
+    componentDidMount () {
+        document.addEventListener('mousemove', this.handleMouseMove);
+    }
+
+    componentWillUnmount () {
+        document.removeEventListener('mousemove', this.handleMouseMove);
+    }
+    
+    handleMouseMove (event) {
+        this.setState({x: event.clientX, y: event.clientY});
+    }
+
+    render () {
+        if (!this.props.show) return null;
+        return (
+            <div
+                className={styles.mysteryMode}
+                style={{
+                    backgroundPosition: `${this.state.x + 2000}px ${this.state.y + 2000}px`
+                }}
+            />
+        );
+    }
+}
+
+MysteryMode.propTypes = {
+    show: PropTypes.bool
+};
+
+const mapStateToProps = state => ({
+    // This is the button's mode, as opposed to the actual current state
+    show: state.scratchGui.mysteryMode
+});
+
+export default connect(
+    mapStateToProps
+)(MysteryMode);

src/components/stage/stage.css

@@ -108,7 +108,12 @@ to adjust for the border using a different method */
     left: 0;
     z-index: $z-index-dragging-sprite;
     filter: drop-shadow(5px 5px 5px $ui-black-transparent);
- }
+}
+
+.dragging-sprite.wobbly {
+    /* prevent overflow (when canvas crosses the right edge of the page) from causing a scrollbar to appear */
+    position: fixed;
+}
 
 .stage-bottom-wrapper {
     position: absolute;

src/components/stage/stage.jsx

@@ -29,6 +29,8 @@ const StageComponent = props => {
         onDeactivateColorPicker,
         onDoubleClick,
         onQuestionAnswered,
+        wobblyDragging,
+        wobblyDragRef,
         ...boxProps
     } = props;
 
@@ -118,12 +120,23 @@ const StageComponent = props => {
                         </div>
                     )}
                 </div>
-                <canvas
-                    className={styles.draggingSprite}
-                    height={0}
-                    ref={dragRef}
-                    width={0}
-                />
+                {
+                    // Give the canvases two different keys to prevent React from recycling the same canvas
+                    // across two different context types (2D and WebGL)
+                    wobblyDragging ? <canvas
+                        className={classNames(styles.draggingSprite, styles.wobbly)}
+                        height={0}
+                        ref={wobblyDragRef}
+                        width={0}
+                        key="non-wobbly"
+                    /> : <canvas
+                        className={styles.draggingSprite}
+                        height={0}
+                        ref={dragRef}
+                        width={0}
+                        key="wobbly"
+                    />
+                }
             </Box>
             {isColorPicking ? (
                 <Box
@@ -147,7 +160,9 @@ StageComponent.propTypes = {
     onQuestionAnswered: PropTypes.func,
     question: PropTypes.string,
     stageSize: PropTypes.oneOf(Object.keys(STAGE_DISPLAY_SIZES)).isRequired,
-    useEditorDragStyle: PropTypes.bool
+    useEditorDragStyle: PropTypes.bool,
+    wobblyDragging: PropTypes.bool,
+    wobblyDragRef: PropTypes.func
 };
 StageComponent.defaultProps = {
     dragRef: () => {}

src/containers/mystery-mode.jsx

@@ -0,0 +1,60 @@
+import bindAll from 'lodash.bindall';
+import PropTypes from 'prop-types';
+import React from 'react';
+import {connect} from 'react-redux';
+
+/**
+ * Turbo Mode component passes toggleTurboMode function to its child.
+ * It also includes `turboMode` in the props passed to the children.
+ * It expects this child to be a function with the signature
+ *     function (toggleTurboMode, {turboMode, ...props}) {}
+ * The component can then be used to attach turbo mode setting functionality
+ * to any other component:
+ *
+ * <TurboMode>{(toggleTurboMode, props) => (
+ *     <MyCoolComponent
+ *         turboEnabled={props.turboMode}
+ *         onClick={toggleTurboMode}
+ *         {...props}
+ *     />
+ * )}</TurboMode>
+ */
+class TurboMode extends React.Component {
+    constructor (props) {
+        super(props);
+        bindAll(this, [
+            'toggleTurboMode'
+        ]);
+    }
+    toggleTurboMode () {
+        this.props.vm.setTurboMode(!this.props.turboMode);
+    }
+    render () {
+        const {
+            /* eslint-disable no-unused-vars */
+            children,
+            vm,
+            /* eslint-enable no-unused-vars */
+            ...props
+        } = this.props;
+        return this.props.children(this.toggleTurboMode, props);
+    }
+}
+
+TurboMode.propTypes = {
+    children: PropTypes.func,
+    turboMode: PropTypes.bool,
+    vm: PropTypes.shape({
+        setTurboMode: PropTypes.func
+    })
+};
+
+const mapStateToProps = state => ({
+    vm: state.scratchGui.vm,
+    turboMode: state.scratchGui.vmStatus.turbo
+});
+
+export default connect(
+    mapStateToProps,
+    () => ({}) // omit dispatch prop
+)(TurboMode);

src/containers/stage.jsx

@@ -10,6 +10,7 @@ import {getEventXY} from '../lib/touch-utils';
 import VideoProvider from '../lib/video/video-provider';
 import {SVGRenderer as V2SVGAdapter} from 'scratch-svg-renderer';
 import {BitmapAdapter as V2BitmapAdapter} from 'scratch-svg-renderer';
+import RubberCanvas from '../lib/rubber-canvas';
 
 import StageComponent from '../components/stage/stage.jsx';
 
@@ -39,9 +40,11 @@ class Stage extends React.Component {
             'updateRect',
             'questionListener',
             'setDragCanvas',
+            'setWobblyDragCanvas',
             'clearDragCanvas',
             'drawDragCanvas',
-            'positionDragCanvas'
+            'positionDragCanvas',
+            '_updateWobblyCanvas'
         ]);
         this.state = {
             mouseDownTimeoutId: null,
@@ -77,6 +80,13 @@ class Stage extends React.Component {
         this.attachMouseEvents(this.canvas);
         this.updateRect();
         this.props.vm.runtime.addListener('QUESTION', this.questionListener);
+
+        // The GUI component seems to be recreated when entering/exiting editor mode.
+        // If we only update mystery mode in componentDidUpdate, it won't
+        // update when switching between editor and player mode.
+        if (this.props.mysteryMode !== this.renderer._mystery.modeActive) {
+            this.renderer.setMysteryMode(this.props.mysteryMode);
+        }
     }
     shouldComponentUpdate (nextProps, nextState) {
         return this.props.stageSize !== nextProps.stageSize ||
@@ -85,7 +95,9 @@ class Stage extends React.Component {
             this.props.isFullScreen !== nextProps.isFullScreen ||
             this.state.question !== nextState.question ||
             this.props.micIndicator !== nextProps.micIndicator ||
-            this.props.isStarted !== nextProps.isStarted;
+            this.props.isStarted !== nextProps.isStarted ||
+            this.props.mysteryMode !== nextProps.mysteryMode ||
+            this.props.wobblyDragging !== nextProps.wobblyDragging;
     }
     componentDidUpdate (prevProps) {
         if (this.props.isColorPicking && !prevProps.isColorPicking) {
@@ -93,6 +105,9 @@ class Stage extends React.Component {
         } else if (!this.props.isColorPicking && prevProps.isColorPicking) {
             this.stopColorPickingLoop();
         }
+        if (this.props.mysteryMode !== prevProps.mysteryMode) {
+            this.renderer.setMysteryMode(this.props.mysteryMode);
+        }
         this.updateRect();
         this.renderer.resize(this.rect.width, this.rect.height);
     }
@@ -197,7 +212,11 @@ class Stage extends React.Component {
             // Editor drag style only updates the drag canvas, does full update at the end of drag
             // Non-editor drag style just updates the sprite continuously.
             if (this.props.useEditorDragStyle) {
-                this.positionDragCanvas(mousePosition[0], mousePosition[1]);
+                if (this.props.wobblyDragging) {
+                    this.wobblyDragCanvas.updateMousePosition(mousePosition);
+                } else {
+                    this.positionDragCanvas(mousePosition[0], mousePosition[1]);
+                }
             } else {
                 const spritePosition = this.getScratchCoords(mousePosition[0], mousePosition[1]);
                 this.props.vm.postSpriteInfo({
@@ -326,14 +345,19 @@ class Stage extends React.Component {
         this.dragCanvas.style.display = 'block';
     }
     clearDragCanvas () {
-        this.dragCanvas.width = this.dragCanvas.height = 0;
-        this.dragCanvas.style.display = 'none';
+        const dragCanvas = this.props.wobblyDragging ? this.wobblyDragCanvas._canvas : this.dragCanvas;
+        dragCanvas.width = dragCanvas.height = 0;
+        dragCanvas.style.display = 'none';
     }
     positionDragCanvas (mouseX, mouseY) {
         // mouseX/Y are relative to stage top/left, and dragCanvas is already
         // positioned so that the pick location is at (0,0).
         this.dragCanvas.style.transform = `translate(${mouseX}px, ${mouseY}px)`;
     }
+    _updateWobblyCanvas (timestamp) {
+        this.wobblyDragCanvas.step(timestamp);
+        if (this.state.isDragging) window.requestAnimationFrame(this._updateWobblyCanvas);
+    }
     onStartDrag (x, y) {
         if (this.state.dragId) return;
         const drawableId = this.renderer.pick(x, y);
@@ -349,6 +373,8 @@ class Stage extends React.Component {
         // Dragging always brings the target to the front
         target.goToFront();
 
+        // Ensure drag canvas' bounds are tight by forcing renderer to generate tight bounds
+        this.renderer.getBounds(drawableId);
         // Extract the drawable art
         const drawableData = this.renderer.extractDrawable(drawableId, x, y);
 
@@ -357,10 +383,17 @@ class Stage extends React.Component {
             isDragging: true,
             dragId: targetId,
             dragOffset: drawableData.scratchOffset
+        }, () => {
+            if (this.props.wobblyDragging && this.props.useEditorDragStyle) this._updateWobblyCanvas(performance.now());
         });
         if (this.props.useEditorDragStyle) {
-            this.drawDragCanvas(drawableData);
-            this.positionDragCanvas(x, y);
+            if (this.props.wobblyDragging) {
+                this.wobblyDragCanvas.reinit(drawableData, x, y);
+            } else {
+                this.drawDragCanvas(drawableData);
+                this.positionDragCanvas(x, y);
+            }
+
             this.props.vm.postSpriteInfo({visible: false});
         }
     }
@@ -400,6 +433,13 @@ class Stage extends React.Component {
     setDragCanvas (canvas) {
         this.dragCanvas = canvas;
     }
+    setWobblyDragCanvas (canvas) {
+        if (this.wobblyDragCanvas) {
+            this.wobblyDragCanvas.destroy();
+            this.wobblyDragCanvas = null;
+        }
+        if (canvas) this.wobblyDragCanvas = new RubberCanvas(canvas);
+    }
     render () {
         const {
             vm, // eslint-disable-line no-unused-vars
@@ -414,6 +454,7 @@ class Stage extends React.Component {
                 question={this.state.question}
                 onDoubleClick={this.handleDoubleClick}
                 onQuestionAnswered={this.handleQuestionAnswered}
+                wobblyDragRef={this.setWobblyDragCanvas}
                 {...props}
             />
         );
@@ -429,7 +470,9 @@ Stage.propTypes = {
     onDeactivateColorPicker: PropTypes.func,
     stageSize: PropTypes.oneOf(Object.keys(STAGE_DISPLAY_SIZES)).isRequired,
     useEditorDragStyle: PropTypes.bool,
-    vm: PropTypes.instanceOf(VM).isRequired
+    vm: PropTypes.instanceOf(VM).isRequired,
+    mysteryMode: PropTypes.bool,
+    wobblyDragging: PropTypes.bool
 };
 
 Stage.defaultProps = {
@@ -442,7 +485,10 @@ const mapStateToProps = state => ({
     isStarted: state.scratchGui.vmStatus.started,
     micIndicator: state.scratchGui.micIndicator,
     // Do not use editor drag style in fullscreen or player mode.
-    useEditorDragStyle: !(state.scratchGui.mode.isFullScreen || state.scratchGui.mode.isPlayerOnly)
+    useEditorDragStyle: !(state.scratchGui.mode.isFullScreen || state.scratchGui.mode.isPlayerOnly),
+    mysteryMode: state.scratchGui.mysteryMode && !(
+        state.scratchGui.mode.isFullScreen || state.scratchGui.mode.isPlayerOnly),
+    wobblyDragging: state.scratchGui.wobblyDragging
 });
 
 const mapDispatchToProps = dispatch => ({

src/lib/libraries/decks/index.jsx

@@ -51,6 +51,9 @@ import libraryCodeCartoon from './thumbnails/code-a-cartoon.jpg';
 // Talking Tales
 import libraryTalking from './thumbnails/talking.png';
 
+// Sprite Mystery
+import librarySpriteMystery from './thumbnails/sprite-mystery.png';
+
 // Videos
 import recordASound from './thumbnails/record-a-sound.jpg';
 import glideAroundThumb from './thumbnails/glide-around.jpg';
@@ -497,6 +500,21 @@ export default {
         urlId: 'animations-that-talk'
     },
 
+    'sprite-mystery': {
+        name: 'How to Find a Sprite',
+        img: librarySpriteMystery,
+        steps: [{
+            video: 'sprite-mystery'
+        }, {
+            deckIds: [
+                'intro-move-sayhello',
+                'add-sprite'
+            ]
+        }
+        ],
+        urlId: 'sprite-mystery'
+    },
+
     'talking': {
         name: (
             <FormattedMessage

src/lib/libraries/decks/translate-video.js

@@ -129,6 +129,9 @@ const videos = {
     },
     'talking': {
         en: 'j0208mq4qi'
+    },
+    'sprite-mystery': {
+        en: 's69h0y6cs4'
     }
 };
 

src/lib/rubber-canvas-frag.glsl

@@ -0,0 +1,8 @@
+precision mediump float;
+
+uniform sampler2D u_image0;
+varying vec2 v_texCoord;
+
+void main () {
+	gl_FragColor = texture2D(u_image0, v_texCoord);
+}

src/lib/rubber-canvas-vert.glsl

@@ -0,0 +1,15 @@
+precision mediump float;
+
+uniform vec4 u_bounds;
+attribute vec2 a_position;
+attribute vec2 a_texCoord;
+
+varying vec2 v_texCoord;
+
+void main () {
+	vec2 boundsSize = u_bounds.zw - u_bounds.xy;
+	vec2 adjusted = a_position - vec2(u_bounds.x, u_bounds.y);
+	vec4 pos = vec4(((adjusted / boundsSize) - 0.5) * vec2(2.0, -2.0), 0.0, 1.0);
+	v_texCoord = a_texCoord;
+	gl_Position = pos;
+}

src/lib/rubber-canvas.js

@@ -0,0 +1,358 @@
+import VERTEX_SOURCE from 'raw-loader!./rubber-canvas-vert.glsl';
+import FRAGMENT_SOURCE from 'raw-loader!./rubber-canvas-frag.glsl';
+
+const DAMPING = 20;
+class _Spring {
+    constructor (opts) {
+        this.reinit(opts);
+    }
+
+    reinit (opts) {
+        if (Object.prototype.hasOwnProperty.call(opts, 'stiffness')) this.stiffness = opts.stiffness;
+        if (Object.prototype.hasOwnProperty.call(opts, 'mass')) this.mass = opts.mass;
+        this.anchor = opts.anchor;
+        this.position = opts.anchor.slice(0);
+        this._velocity = [0, 0];
+    }
+
+    step (deltaTime) {
+        const springForceX = -this.stiffness * (this.position[0] - this.anchor[0]);
+        const springForceY = -this.stiffness * (this.position[1] - this.anchor[1]);
+
+        const dampingForceX = (DAMPING * this.mass) * this._velocity[0];
+        const dampingForceY = (DAMPING * this.mass) * this._velocity[1];
+
+        const forceX = springForceX - dampingForceX;
+        const forceY = springForceY - dampingForceY;
+
+        const accelerationX = forceX / this.mass;
+        const accelerationY = forceY / this.mass;
+
+        this._velocity[0] += accelerationX * deltaTime;
+        this._velocity[1] += accelerationY * deltaTime;
+
+        this.position[0] += this._velocity[0] * deltaTime;
+        this.position[1] += this._velocity[1] * deltaTime;
+    }
+}
+
+const createShader = (gl, source, type) => {
+    const shader = gl.createShader(type);
+    gl.shaderSource(shader, source);
+    gl.compileShader(shader);
+
+    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
+        const info = gl.getShaderInfoLog(shader);
+        throw new Error(`Could not compile WebGL program. \n${info}`);
+    }
+
+    return shader;
+};
+
+const createProgram = (gl, vertSource, fragSource) => {
+    const vertShader = createShader(gl, vertSource, gl.VERTEX_SHADER);
+    const fragShader = createShader(gl, fragSource, gl.FRAGMENT_SHADER);
+
+    const program = gl.createProgram();
+    gl.attachShader(program, vertShader);
+    gl.attachShader(program, fragShader);
+    gl.linkProgram(program);
+
+    const programInfo = {
+        uniforms: {},
+        attribs: {},
+        program
+    };
+
+    // Construct maps of uniform + attrib locations for convenience
+    const numActiveUniforms = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);
+    for (let i = 0; i < numActiveUniforms; i++) {
+        const uniformInfo = gl.getActiveUniform(program, i);
+        programInfo.uniforms[uniformInfo.name] = gl.getUniformLocation(program, uniformInfo.name);
+    }
+
+    const numActiveAttributes = gl.getProgramParameter(program, gl.ACTIVE_ATTRIBUTES);
+    for (let i = 0; i < numActiveAttributes; i++) {
+        const attribInfo = gl.getActiveAttrib(program, i);
+        programInfo.attribs[attribInfo.name] = gl.getAttribLocation(program, attribInfo.name);
+    }
+
+    return programInfo;
+};
+
+// Resolution of the grid in terms of grid squares. In this case, that's 16 squares and 25 vertices.
+const SUBDIVISIONS = 4;
+
+class RubberCanvas {
+    constructor (canvas) {
+        this._canvas = canvas;
+        this._gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');
+        this._size = [0, 0];
+        this._mousePosition = [0, 0];
+
+        const numPoints = (SUBDIVISIONS + 1) ** 2;
+        this._springs = [];
+        for (let i = 0; i < numPoints; i++) {
+            this._springs.push(new _Spring({
+                anchor: [0, 0],
+                position: [0, 0]
+            }));
+        }
+
+        this._vertexData = new Float32Array(numPoints * 2);
+        this._texCoordData = new Float32Array(numPoints * 2);
+        this._vertexIndices = new Uint16Array(numPoints * 6);
+
+        // Initialize texture coordinates for all grid points
+        for (let x = 0; x <= SUBDIVISIONS; x++) {
+            for (let y = 0; y <= SUBDIVISIONS; y++) {
+                const index = (y * (SUBDIVISIONS + 1)) + x;
+                this._texCoordData[index * 2] = x / SUBDIVISIONS;
+                this._texCoordData[(index * 2) + 1] = y / SUBDIVISIONS;
+            }
+        }
+
+        // Initialize vertex indices
+        for (let x = 0; x < SUBDIVISIONS; x++) {
+            for (let y = 0; y < SUBDIVISIONS; y++) {
+                const topLeftIndex = (y * (SUBDIVISIONS + 1)) + x;
+                const topRightIndex = (y * (SUBDIVISIONS + 1)) + x + 1;
+                const bottomLeftIndex = ((y + 1) * (SUBDIVISIONS + 1)) + x;
+                const bottomRightIndex = ((y + 1) * (SUBDIVISIONS + 1)) + x + 1;
+
+                this._vertexIndices[topLeftIndex * 6] = topLeftIndex;
+                this._vertexIndices[(topLeftIndex * 6) + 1] = topRightIndex;
+                this._vertexIndices[(topLeftIndex * 6) + 2] = bottomLeftIndex;
+
+                this._vertexIndices[(topLeftIndex * 6) + 3] = bottomLeftIndex;
+                this._vertexIndices[(topLeftIndex * 6) + 4] = topRightIndex;
+                this._vertexIndices[(topLeftIndex * 6) + 5] = bottomRightIndex;
+            }
+        }
+
+        // Used for delta-time calculation
+        this._lastTimestamp = 0;
+
+        const gl = this._gl;
+        this._shader = createProgram(gl, VERTEX_SOURCE, FRAGMENT_SOURCE);
+
+        this._vertexBuffer = gl.createBuffer();
+        this._indexBuffer = gl.createBuffer();
+        this._texCoordBuffer = gl.createBuffer();
+        gl.enableVertexAttribArray(this._shader.attribs.a_position);
+        gl.enableVertexAttribArray(this._shader.attribs.a_texCoord);
+
+        // The texture coordinates and vertex indices will never change, so send them over to the GPU here
+        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this._indexBuffer);
+        gl.bufferData(
+            gl.ELEMENT_ARRAY_BUFFER,
+            this._vertexIndices,
+            gl.STATIC_DRAW
+        );
+
+        gl.bindBuffer(gl.ARRAY_BUFFER, this._texCoordBuffer);
+        gl.vertexAttribPointer(
+            this._shader.attribs.a_texCoord,
+            2, // vec2
+            gl.FLOAT,
+            false,
+            0,
+            0
+        );
+        gl.bufferData(
+            gl.ARRAY_BUFFER,
+            this._texCoordData,
+            gl.STATIC_DRAW
+        );
+
+        gl.activeTexture(gl.TEXTURE0);
+        this._texture = gl.createTexture();
+
+        // This will be correct if https://github.com/LLK/scratch-render/pull/556 goes in in time
+        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, true);
+
+        gl.clearColor(0, 0, 0, 0);
+    }
+
+    reinit (drawableData, x, y) {
+        const {
+            width,
+            height,
+            x: grabX,
+            y: grabY
+        } = drawableData;
+
+        this._setData(drawableData);
+
+        // Reinitialize springs' mass based on their distance to the point at which the sprite was grabbed
+        for (let i = 0; i <= SUBDIVISIONS; i++) {
+            const springX = (i / SUBDIVISIONS) * width;
+
+            for (let j = 0; j <= SUBDIVISIONS; j++) {
+                const springY = (j / SUBDIVISIONS) * height;
+
+                const distance = Math.hypot(springX - grabX, springY - grabY);
+                const distanceScaled = distance / Math.hypot(width, height);
+                this._springs[(j * (SUBDIVISIONS + 1)) + i].reinit({
+                    anchor: [springX + x, springY + y],
+                    position: [springX + x, springY + y],
+                    stiffness: 15,
+                    mass: (distanceScaled * 0.05) + 0.025
+                });
+            }
+        }
+
+        this._lastTimestamp = performance.now();
+        const {x: parentX, y: parentY} = this._canvas.parentElement.getBoundingClientRect();
+        this._canvas.style.left = `${-grabX + parentX}px`;
+        this._canvas.style.top = `${-grabY + parentY}px`;
+        this._canvas.style.display = 'block';
+        this.step();
+    }
+
+    // Calculate the bounds of the dragged sprite after being jellofied.
+    _calculateBounds () {
+        let left = Infinity;
+        let right = -Infinity;
+        let top = Infinity;
+        let bottom = -Infinity;
+
+        for (const spring of this._springs) {
+            left = Math.min(left, spring.position[0]);
+            right = Math.max(right, spring.position[0]);
+            top = Math.min(top, spring.position[1]);
+            bottom = Math.max(bottom, spring.position[1]);
+        }
+
+        left = Math.floor(left);
+        right = Math.ceil(right);
+        bottom = Math.ceil(bottom);
+        top = Math.floor(top);
+
+        return {left, right, top, bottom};
+    }
+
+    _setData (data) {
+        this._size[0] = data.width;
+        this._size[1] = data.height;
+
+        const gl = this._gl;
+
+        gl.bindTexture(gl.TEXTURE_2D, this._texture);
+        // disable automatic mipmapping
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
+        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, data.width, data.height, 0, gl.RGBA, gl.UNSIGNED_BYTE, data.data);
+    }
+
+    updateMousePosition ([x, y]) {
+        this._mousePosition[0] = x;
+        this._mousePosition[1] = y;
+
+        // update springs' destinations to match new mouse position
+        for (let i = 0; i <= SUBDIVISIONS; i++) {
+            const springX = (i / SUBDIVISIONS) * this._size[0];
+
+            for (let j = 0; j <= SUBDIVISIONS; j++) {
+                const springY = (j / SUBDIVISIONS) * this._size[1];
+
+                this._springs[(j * (SUBDIVISIONS + 1)) + i].anchor[0] = springX + x;
+                this._springs[(j * (SUBDIVISIONS + 1)) + i].anchor[1] = springY + y;
+            }
+        }
+    }
+
+    step (timestamp) {
+        // Slightly above 33.3ms (30 FPS)
+        const maxTimeStep = 35;
+
+        let deltaTime = timestamp - this._lastTimestamp;
+
+        // Take multiple steps if deltaTime is too large
+        // This prevents explodage
+        let timeSubdivisions = 1;
+        if (deltaTime > maxTimeStep) {
+            timeSubdivisions = Math.ceil(deltaTime / maxTimeStep);
+            deltaTime /= timeSubdivisions;
+        }
+        this._lastTimestamp = timestamp;
+        if (deltaTime > 0) {
+            for (let i = 0; i < timeSubdivisions; i++) {
+                for (const spring of this._springs) {
+                    // I've got a step() in my _Spring
+                    spring.step(deltaTime / 1000);
+                }
+            }
+        }
+
+        // Update vertex data to match springs' positions
+        for (let i = 0; i < this._springs.length; i++) {
+            const spring = this._springs[i];
+            this._vertexData[i * 2] = spring.position[0];
+            this._vertexData[(i * 2) + 1] = spring.position[1];
+        }
+
+        const gl = this._gl;
+        gl.bindBuffer(gl.ARRAY_BUFFER, this._vertexBuffer);
+        gl.vertexAttribPointer(
+            this._shader.attribs.a_position,
+            2, // vec2
+            gl.FLOAT,
+            false,
+            0,
+            0
+        );
+        gl.bufferData(
+            gl.ARRAY_BUFFER,
+            this._vertexData,
+            gl.DYNAMIC_DRAW
+        );
+
+        const bounds = this._calculateBounds();
+
+        // 10 pixels of slack space to avoid excessive canvas resizing
+        bounds.right += 10;
+        bounds.bottom += 10;
+
+        // Only scale the canvas up, not down-- this also avoids resizing the canvas too much
+        if (bounds.right - bounds.left < this._canvas.width) bounds.right = bounds.left + this._canvas.width;
+        if (bounds.bottom - bounds.top < this._canvas.height) bounds.bottom = bounds.top + this._canvas.height;
+
+        const width = bounds.right - bounds.left;
+        const height = bounds.bottom - bounds.top;
+
+        if (width > 2048 || height > 2048) {
+            // Avoid creating lag spikes from a huge WebGL canvas if the spring simulation blows up
+            return;
+        }
+        this._canvas.width = width;
+        this._canvas.height = height;
+
+        gl.useProgram(this._shader.program);
+        gl.uniform1i(this._shader.uniforms.u_image0, 0);
+        gl.uniform4f(this._shader.uniforms.u_bounds, bounds.left, bounds.top, bounds.right, bounds.bottom);
+
+        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
+        gl.bindTexture(gl.TEXTURE_2D, this._texture);
+
+        gl.clear(gl.COLOR_BUFFER_BIT);
+        gl.viewport(0, 0, width, height);
+        gl.drawElements(gl.TRIANGLES, this._vertexIndices.length, gl.UNSIGNED_SHORT, 0);
+
+        this._canvas.style.transform = `translate(${bounds.left}px, ${bounds.top}px)`;
+    }
+
+    destroy () {
+        const gl = this._gl;
+
+        gl.deleteBuffer(this._texCoordBuffer);
+        gl.deleteBuffer(this._vertexBuffer);
+        gl.deleteBuffer(this._indexBuffer);
+        gl.deleteTexture(this._texture);
+        gl.deleteProgram(this._shader.program);
+    }
+}
+
+export default RubberCanvas;

src/reducers/gui.js

@@ -14,6 +14,8 @@ import modalReducer, {modalsInitialState} from './modals';
 import modeReducer, {modeInitialState} from './mode';
 import monitorReducer, {monitorsInitialState} from './monitors';
 import monitorLayoutReducer, {monitorLayoutInitialState} from './monitor-layout';
+import mysteryModeReducer, {mysteryModeInitialState} from './mystery-mode';
+import wobblyDragReducer, {wobblyDragInitialState} from './wobbly-dragging';
 import projectChangedReducer, {projectChangedInitialState} from './project-changed';
 import projectStateReducer, {projectStateInitialState} from './project-state';
 import projectTitleReducer, {projectTitleInitialState} from './project-title';
@@ -48,6 +50,7 @@ const guiInitialState = {
     modals: modalsInitialState,
     monitors: monitorsInitialState,
     monitorLayout: monitorLayoutInitialState,
+    mysteryMode: mysteryModeInitialState,
     projectChanged: projectChangedInitialState,
     projectState: projectStateInitialState,
     projectTitle: projectTitleInitialState,
@@ -57,7 +60,8 @@ const guiInitialState = {
     timeout: timeoutInitialState,
     toolbox: toolboxInitialState,
     vm: vmInitialState,
-    vmStatus: vmStatusInitialState
+    vmStatus: vmStatusInitialState,
+    wobblyDragging: wobblyDragInitialState
 };
 
 const initPlayer = function (currentState) {
@@ -146,6 +150,7 @@ const guiReducer = combineReducers({
     modals: modalReducer,
     monitors: monitorReducer,
     monitorLayout: monitorLayoutReducer,
+    mysteryMode: mysteryModeReducer,
     projectChanged: projectChangedReducer,
     projectState: projectStateReducer,
     projectTitle: projectTitleReducer,
@@ -155,7 +160,8 @@ const guiReducer = combineReducers({
     timeout: timeoutReducer,
     toolbox: toolboxReducer,
     vm: vmReducer,
-    vmStatus: vmStatusReducer
+    vmStatus: vmStatusReducer,
+    wobblyDragging: wobblyDragReducer
 });
 
 export {

src/reducers/mystery-mode.js

@@ -0,0 +1,26 @@
+const TOGGLE_MYSTERY_MODE = 'scratch-gui/mystery-mode/TOGGLE_MYSTERY_MODE';
+
+const initialState = false;
+
+const reducer = function (state, action) {
+    if (typeof state === 'undefined') state = initialState;
+
+    switch (action.type) {
+    case TOGGLE_MYSTERY_MODE:
+        return !state;
+    default:
+        return state;
+    }
+};
+
+const toggleMysteryMode = function () {
+    return {
+        type: TOGGLE_MYSTERY_MODE
+    };
+};
+
+export {
+    reducer as default,
+    initialState as mysteryModeInitialState,
+    toggleMysteryMode
+};

src/reducers/wobbly-dragging.js

@@ -0,0 +1,26 @@
+const TOGGLE_WOBBLE = 'scratch-gui/mystery-mode/TOGGLE_WOBBLE';
+
+const initialState = false;
+
+const reducer = function (state, action) {
+    if (typeof state === 'undefined') state = initialState;
+
+    switch (action.type) {
+    case TOGGLE_WOBBLE:
+        return !state;
+    default:
+        return state;
+    }
+};
+
+const toggleWobblyDragging = function () {
+    return {
+        type: TOGGLE_WOBBLE
+    };
+};
+
+export {
+    reducer as default,
+    initialState as wobblyDragInitialState,
+    toggleWobblyDragging
+};