【Webots 用户指南】<The User Interface>

The User Interface

Webots GUI is composed of four principal windows: the 3D window that displays and allows you to interact with the 3D simulation, the Scene tree which is a hierarchical representation of the current world, the Text editor that allows you to edit source code, and finally, the Console that displays both compilation and controller outputs.

%figure "Webots GUI"

%end

The GUI has nine menus: File, Edit, View, Simulation, Build, Overlays, Tools, Wizards and Help.

File Menu

The File menu allows you to perform usual file operations: loading, saving, etc.

• The New World menu item (and button) opens a new world in the simulation window containing only an ElevationGrid, displayed as a chessboard of 10 x 10 squares on a surface of 1 m x 1 m.

• The Open World... menu item (and button) opens a file selection dialog that allows you to choose a ".wbt" file to load.

• The Open Recent World menu item gives the possibility of reopening a ".wbt" file that was opened recently by choosing it from the list displayed in the submenu.

• The Open Sample World menu item opens a dialog listing all the available sample worlds where it is possible to search for a specific ".wbt" file to load by entering the file name or part of it in the search field.

• The Save World menu item (and button) saves the current world using the current filename (the filename that appears at the top of the main window).
  On each Save the content of the ".wbt" file is overwritten and no backup copies are created by Webots, therefore you should use this button carefully and eventually do safety copies manually.

• The Save World As... menu item (and button) saves the current world with a new filename entered by the user.
  Note that a ".wbt" file should always be saved in a Webots project directory, and in the "worlds" subdirectory, otherwise it will not be possible to reopen the file.

• The Reload World menu item (and button) reloads the current world from the saved version and restarts the simulation from the beginning.

  Note:
  When opening (or reloading) a world, if the world takes more than 2 seconds to
  load a window will pop up and show the progression. Using this window it is
  possible to cancel the loading of the world, in that case, the empty world will
  be opened instead.

• The Reset Simulation menu item (and button) restores the initial state of the simulation.
  The simulation is not entirely destroyed and reconstructed as with a reload, but the initial state of all nodes is restored, which is much faster.

  Note:
  In order to reset the simulation, the following steps are performed:

  • The simulation time is set to 00:00:00
  • All nodes added during the simulation are removed.
  • All sound sources are stopped.
  • The random seeds used by Webots internally are reset.
  • All the nodes are reset. This has the following implication depending on the node type:
    • Brake: The brake is released.
    • Charger: The battery field and the emissiveColor field of the Material node of the first Shape child node are restored.
    • Connector: If attached, the connector is detached and the value of the isLocked field is restored.
    • Display: The image is cleared.
    • Emitter/Receiver: The message queue is cleared.
    • Joint/Motor: The position, velocity, acceleration, available torque and available force are restored.
    • LED: If the first child is a Light node, it‘s color field is restored and it is switched off. If the first child is a Shape node, the emissiveColor field of its Material node is restored.
    • Lidar: The position of the rotating head is restored.
    • Pen: All the painted textures are cleaned.
    • Propeller: The slow helix and it‘s initial position are restored.
    • Robot: The battery field is restored, all the supervisor labels are removed, the nodes visibility is restored and the controller is restarted.
    • Solid: The translation and rotation fields are restored and the physics is reset.
    • Track: The motor position is restored and the translation field of the textureTransform node of the Appearance node of the first Shape children node is restored.
    • Viewpoint: The orientation and position fields are restored.

• The New Text File menu item (and button) opens an empty text file in the text editor.

• The Open Text File... menu item (and button) opens a file selection dialog that allows you to choose a text file (for example a ".java" file) to load.

• The Save Text File menu item (and button) saves the current text file.

• The Save Text File As... menu item (and button) saves the current text file with a new filename entered by the user.

• The Save All Text Files menu item saves all the opened and unsaved text files.

• The Revert Text File menu item (and button) reloads the text file from the saved version.

• The Print Preview... menu item opens a window allowing you to manage the page layout in order to print files from the text editor.

• The Print... menu item opens a window allowing you to print the current file of the text editor.

• The Import VRML97... menu item adds VRML97 objects at the end of the scene tree.
  These objects come from a VRML97 file you must specify.
  This feature is useful for importing complex shapes that were modeled in a 3D modelling program, then exported to VRML97 (previously called VRML 2.0).
  Most 3D modelling software, like 3D Studio Max, Maya, AutoCAD, Pro Engineer, AC3D, or Art Of Illusion, include the VRML97 (or VRML 2.0) export feature.
  Be aware that Webots cannot import files in VRML 1.0 format.
  Once imported, these objects appear as Group, Transform or Shape nodes at the bottom of the scene tree.
  You can then either turn these objects into Webots nodes (like Solid, Robot, etc.) or cut and paste them into the children list of existing Webots nodes.

• The Export VRML97... item allows you to save the currently loaded world as a ".wrl" file, conforming to the VRML97 standard.
  Such a file can, in turn, be opened with any VRML97 viewer and most 3D modeling software.

• The Take Screenshot... item allows you to take a screenshot of the current view in Webots.
  It opens a file dialog to save the current view as a PNG or JPG image.

• The Make Movie... item allows you to create MPEG movies (Linux and macOS) or AVI movies (Windows).
  Once the movie recording is started, this item is changed in Stop Movie....
  During the recording, it is possible to change the running mode and pause the simulation.
  However, frames are only captured during Webots steps and not when the simulation is paused.
  Other than choosing the resolution and the compression quality of the movie, it is also possible to record the simulation in accelerated mode or in slow motion by setting the Video acceleration value in the pop-up dialog.
  If the video acceleration value is below 1, the recorded movie will run slower than the simulation.
  The maximum slow down, i.e. the minimum acceleration value, is defined by the basic time step of the simulation because it is not possible to record at a higher frame rate than the simulation update rate.
  In order to increase the maximum slow down you should reduce the simulation basic time step.
  Checking the video caption option will display the acceleration value in the top right corner of the movie.

%figure "‘Make Movie...‘ dialog"

%end

• The Export HTML5 Model... item allows you to export the current world as an interactive 3D ".html" file.
  You can get more information about this topic in this section.

• The Make HTML5 Animation... item allows you to record a simulation as a 3D animation and publish it on a HTML5 web page.
  Once the animation recording is started, this item is changed to Stop HTML5 Animation... and can be used to stop the animation recording.
  You can get more information about this topic in this section.

• Quit terminates the current simulation and closes Webots.

Note: on Windows, "Exit" is used instead of "Quit".

Edit Menu

The Edit menu provides usual text edition functions to manipulate files opened in the Text editor, such as Copy, Paste, Cut, etc.

View Menu

The View menu allows you to control the viewing in the simulation window.

• The Follow Object submenu allows you to switch between a fixed (static) viewpoint and a viewpoint that follows a mobile object (usually a robot).
  If you want the viewpoint to follow an object, first you need to select the object with the mouse and then check one of the items of the submenu depending on the following behavior you want.
  Refer to the Viewpoint documentation for more information about the different following behaviors.

• The Restore Viewpoint item restores the viewpoint‘s position and orientation to their initial settings when the file was loaded or reverted.
  This feature is handy when you get lost while navigating in the scene, and want to return to the original viewpoint.

• Move viewpoint to object moves the viewpoint to center and zoom on the selected node.
  If the selected item is a field, the upper parent node will be targeted.
  The object will be at the center of the 3D view and will be completely visible.

• The Change View submenu moves the viewpoint to align it on any of the six world-aligned axes around the selected object.
  If no object is selected, the viewpoint will be centered on the world origin.
  The available options are Front View, Back View, Left View, Right View, Top View and Bottom View.

• The Fullscreen item enables and disables displaying the 3D window on the entire screen.

• The Virtual Reality Headset submenu allows you to use a virtual reality headset such as the HTC Vive or Oculus Rift to view the simulation:
  • The Enable item allows you to switch the simulation view to the headset.
  • The Track headset position and Track headset orientation items specifies if the headset position and orientation should be tracked and applied to the viewpoint.
  • The View left eye, View right eye and Empty view radio buttons allow you to choose what should be displayed in the simulation view.
    You can either see the left eye image, right eye image or nothing.
  • The Anti-aliasing item allows you to enable anti-aliasing on both eye images (note that anti-aliasing will decrease simulation speed).

  • The headset installation procedure is described here.

    Note:
    This menu is currently present only on Windows.
    If you are on Windows and the menu is not enabled, it indicates that the drivers are not installed or that no headset is connected.

• The Projection radio button group allows you to choose between the Perspective Projection (default) and the Orthographic Projection mode for Webots simulation window.
  The perspective mode corresponds to a natural projection: in which the farther an object is from the viewer, the smaller it appears in the image.
  With the orthographic projection, the distance from the viewer does not affect how large an object appears.
  Furthermore, with the orthographic mode, lines which are parallel in the model are drawn parallel on the screen, therefore this projection is sometimes useful during the modelling phase.
  No shadows are rendered in the orthographic mode.

• The Rendering radio button group allows you to choose between the Plain Rendering (default) and the Wireframe modes for Webots simulation window.
  In plain rendering mode, the objects are rendered with their geometrical faces, materials, colors and textures, in the same way they are usually seen by an eye or a camera.
  In wireframe rendering mode, only the segments of the renderable primitives are rendered.
  This mode can be useful to debug your meshes.
  If the wireframe rendering mode and the View / Optional Rendering / Show All Bounding Objects toggle button are both activated, then only bounding objects are drawn (not the renderable primitives).
  This can be used to debug a problem with the collision detection.

• The Optional Rendering submenu allows you to display, or to hide, supplementary information.
  These renderings are displayed only in the main rendering and hide in the robot camera.
  They are used to understand better the behavior of the simulation:

  • The Show Coordinate System allows you to display, or to hide, the global coordinate system at the bottom right corner of the 3D window as red, green and blue arrows representing the x, y and z axes respectively.

  • The Show All Bounding Objects allows you to display, or to hide, all the bounding objects (defined in the boundingObject fields of every Solid node).
    Bounding objects are represented by white lines.
    These lines turn rose when a collision occurs and blue when the solid is idle, i.e., it comes to rest and it doesn‘t interact with any other active solid.

  • The Show Contact Points allows you to display, or to hide, the contact points generated by the collision detection engine.
    Contact points that do not generate a corresponding contact force are not shown.
    A contact force is generated only for objects simulated with physics (Physics node required).
    A step is required for taking this operation into account.

  • The Show Connector Axes allows you to display, or to hide, the connector axes.
    The rotation alignments are depicted in black while the y and z axes respectively in green and blue.

  • The Show Joint Axes allows you to display, or to hide, the joint axes.
    The joint axes are represented by black lines.

  • The Show RangeFinder Frustums allows you to display, or to hide, the OpenGL culling frustum and the recorded image for every range-finder in the scene, using a yellow wire frame.
    If the range-finder device is disabled or the first image is not available yet, the frustum will be drawn in gray.
    The OpenGL culling frustum is a truncated pyramid corresponding to the field of view of a range-finder.
    The recorded image is displayed on the plane described by the frustum at a distance corresponding to the minimum range of the range-finder from the device center.
    More information about this concept is available in the OpenGL documentation.

  • The Show Lidar Rays Paths allows you to display, or to hide, the layers (the laser ray paths) for every lidar in the scene, using a cyan wire frame.
    If the lidar device is disabled or the first measurement is not available yet, the layers are drawn in gray.

  • The Show Lidar Point Cloud allows you to display, or to hide, the point cloud for every lidar enabled in point cloud mode in the scene.
    The point cloud is represented by the location of the points themselves and by the rays from the lidar origin to the points using a gradient from blue (top layer) to red (bottom layer).
    This optional rendering is computationally expensive and can therefore significantly slow-down the simulation speed.
    Note that if the point cloud contains more than 2500 points, the rays from the lidar origin to the point are not displayed.

  • The Show Camera Frustums allows you to display, or to hide, the OpenGL culling frustum and the recorded image for every camera in the scene, using a magenta wire frame.
    If the camera device is disabled or the first image is not available yet, the frustum will be drawn in gray.
    The OpenGL culling frustum is a truncated pyramid corresponding to the field of view of a camera.
    The back of the pyramid is not represented because the far plane is set to infinity.
    The recorded image is displayed on the camera‘s near plane.
    More information about this concept is available in the OpenGL documentation.

  • The Show DistanceSensor Rays allows you to display, or to hide, the rays casted by the distance sensor devices.
    These rays are drawn as red lines (which become green beyond collision points).
    Their length corresponds to the maximum range of the device.
    If the distance sensor device is disabled or the first measurement is not available yet, the rays will be drawn in gray.

  • The Show LightSensor Rays allows you to display, or to hide, the rays casted by the light sensor devices.
    These rays are drawn as yellow lines.
    If the light sensor device is disabled or the first measurement is not available yet, the rays will be drawn in gray.

  • The Show Light Positions allows you to display, or to hide, the position of PointLight and SpotLight lights.
    DirectionalLight nodes aren‘t represented.
    PointLight and SpotLight nodes are represented by a colored circle surrounded by a flare.

  • The Show Pen Painting Rays allows you to display, or to hide, the rays in which the pen devices paint.
    These rays are drawn as violet lines if painting is enabled, otherwise as gray lines.

  • The Show Radar Frustums allows you to display, or to hide, the radar frustum.
    If the radar device is enabled the frustum is drawn in blue, otherwise if the radar is disabled or the first measurement is not available yet, the frustum is drawn in gray.
    The radar frustum represents the volume in which a target can be detected by the radar.

  • The Show Center Of Mass allows you to display, or to hide, the global center of mass of a selected solid with non NULL Physics node.
    The center of mass is rendered in dark blue.

  • The Show Center Of Buoyancy allows you to display, or to hide, the global center of buoyancy of a selected solid with non NULL Physics node.
    The center of buoyancy is rendered in purple.

  • The Show Support Polygon allows you to display, or to hide, the support polygon of a selected solid with non NULL Physics node.
    By support polygon we mean the projection of the convex hull of the solid‘s contact points on the horizontal plane which contains the lowest one.
    In addition, the projection of the center of mass in the latter plane is rendered in green if it lies inside the support polygon (static equilibrium), red otherwise.
    This rendering option can be activated only for solids with no other solid at their top.

• If the Disable selection option is enabled, it prevents you from changing the selected solid node when clicking on the 3D window.
  This is particularly useful during the modeling phase, when you want to change the viewpoint without modifying the visible and selected fields in the scene tree.

• If the Lock Viewpoint option is enabled, it prevents you from changing the position and orientation of the Viewpoint node when dragging the mouse or moving the mouse wheel on the 3D window.
  This is particularly useful when you don‘t want to change accidently the position and orientation of the viewpoint.

Note:
The Follow Object, Follow Object and Rotate, Projection, Rendering, Optional Rendering Items, Disable Selection and Lock Viewpoint options are saved per world whereas the other options are global.

Simulation Menu

The Simulation menu is used to control the simulation mode.

• The Pause menu item (and button) pauses the simulation.

• The Step menu item (and button) executes one basic time step of simulation.
  The duration of this step is defined in the basicTimeStep field of the WorldInfo node, and can be adjusted in the scene tree window to suit your needs.

• The Real-time menu item (and button) runs the simulation at real-time until it is interrupted by Pause or Step.
  In run mode, the 3D display of the scene is refreshed every n basic time steps, where n is defined in the displayRefresh field of the WorldInfo node.

• The Run menu item (and button) is like Real-time, except that it runs as fast as possible.

• The Fast menu item (and button) is like Run, except that no graphical rendering is performed.
  As the graphical rendering is disabled (black screen) this allows for a faster simulation and therefore is well suited for cpu-intensive simulations (genetic algorithms, vision, learning, etc.).

Build Menu

The Build menu provides the functionality to compile (or cross-compile) controller code.
The build menu is described in more details here.

Overlays Menu

The Overlays menu provides actions specific to rendering device overlays (Camera, Display, Rangefinder).
Some actions of this menu are active only when a robot is selected in the 3D window or when there is only one robot in the simulation:

• The Camera Devices submenu contains the list of all the camera devices of the selected robot and its descendant robots and lets the user show or hide single camera overlay images by checking or unchecking the corresponding item.
  Camera overlays differ from the display overlays because of their magenta border.
  Note that if the Hide All Camera Overlays item is checked, then the camera device overlays will not be visible in the 3D view independently from the status of Camera Devices menu items.
  A Camera Devices menu item is disabled if the overlay‘s texture is shown in an external window by double-clicking on it.

• The RangeFinder Devices submenu contains the list of all the range-finder devices of the selected robot and its descendant robots and lets the user show or hide single range-finder overlay images by checking or unchecking the corresponding item.
  Range-finder overlays differ from the camera overlays because of their yellow border.
  Note that if the Hide All RangeFinder Overlays item is checked, then the range-finder device overlays will not be visible in the 3D view independently from the status of RangeFinder Devices menu items.
  A RangeFinder Devices menu item is disabled if the overlay‘s texture is shown in an external window by double-clicking on it.

• The Display Devices submenu contains the list of all the display devices of the selected robot and its descendant robots and lets the user show or hide single display overlay images by checking or unchecking the corresponding item.
  Display overlays differ from the camera overlays because of their cyan border.
  Note that if the Hide All Display Overlays item is checked, then the display device overlays will not be visible in the 3D view independently from the status of Display Devices menu items.
  A Display Devices menu item is disabled if the overlay‘s texture is shown in an external window by double-clicking on it.

On the other hand the following items are always active and apply to all the robots in the world:

• The Hide All Camera Overlays option hides all the camera devices overlays in the 3D view independently from the specific robot‘s device option set in Camera Devices submenu.

• The Hide All RangeFinder Overlays option hides all the camera devices overlays in the 3D view independently from the specific robot‘s device option set in RangeFinder Devices submenu.

• The Hide All Display Overlays option hides all the display devices overlays in the 3D view independently from the specific robot‘s device option set in Display Devices submenu.

Tools Menu

The Tools menu allows you to open various Webots windows.

• The 3D View menu item shows or hides the 3D window that and allows you to interact with the 3D simulation.

• The Scene Tree menu item opens the Scene Tree window in which you can edit the virtual world.
  Alternatively it is also possible to double-click on some of the objects in the main window: this automatically opens the Scene Tree with the corresponding object selected.

• The Text Editor menu item opens the Webots text editor.
  This editor can be used for editing and compiling controller source code.

• The Console menu item opens the Webots Console, which is a read-only console that is used to display Webots error messages and controller outputs.

• The Documentation menu item shows or hides the offline Webots documentation window.

• The Restore Layout menu item restores the factory layout of the panels of the main window.

• The Clear Console menu item clears the console.

• The Edit Physics Plugin menu item opens the source code of the physics plugin in the text editor.

• The Preferences item pops up a window described in this section.

Wizards Menu

The Wizards menu makes it easier to create new projects and new controllers.

• The New Project Directory... menu item first prompts you to choose a filesystem location and then it creates a project directory.
  A project directory contains several subdirectories that are used to store the files related to a particular Webots project, i.e. world files, controller files, data files, plugins, etc. Webots remembers the current project directory and automatically opens and saves any type of file from the corresponding subdirectory of the current project directory.

• The New Robot Controller... menu item allows you to create a new controller program.
  You will first be prompted to choose between a C, C++, Java, Python or MATLAB^TM controller.
  If you choose C or C++ on Windows, Webots will offer you the possibility to create a Makefile / gcc project or a Visual Studio project.
  Then, Webots will ask you to enter the name of your controller and finally it will create all the necessary files (including a template source code file) in your current project directory.

• The New Physics Plugin... menu item will let you create a new physics plugin for your project.
  Webots asks you to choose a programming language (C or C++) and a name for the new physics plugin.
  Then it creates a directory, a template source code file and a Makefile in your current project.

Help Menu

The Help menu makes it easier to access the documentation, support and general information.

• The About... item opens the About... window that displays the license information.

• The Webots Guided Tour... menu item starts a guided tour that demonstrates Webots capabilies through a series of examples.

• The Check for updates... item pops up a window informing if the Webots version in use is the latest one and providing the link to download the latest version if needed.

• The OpenGL Information... menu item gives you information about your current OpenGL hardware and driver.
  It can be used to diagnose rendering problems.

The remaining menu items bring up various information as indicated, in the form of HTML pages, PDF documents, etc.

Main Toolbar

The main toolbar contains a button for adding new nodes to the world, the speedometer (see this subsection) and shortcuts to items of the File, Simulation and View menus.

• Hide/Show Scene Tree: shows or hides the Scene Tree and resizes the 3D window consequently.

• Add: Adds a node or an object.
  For nodes, this triggers a dialog that will let you choose a node type from a list.
  The new node is created with default values that can be modified afterwards.
  You can only insert a node suitable for the corresponding field.
  The dialog also gives the possibility to load a previously exported node by clicking on the Import... button.
  Further information about how to export a node are available here.

Speedometer and Virtual Time

A speedometer (see this figure) indicates the speed of the simulation on your computer.
It is displayed on the main toolbar, and indicates how fast the simulation runs compared to real time.
In other words, it represents the speed of the virtual time.
If the value of the speedometer is 2, it means that your computer simulation is running twice as fast as the corresponding real robots would.
This information is valid both in Run mode and Fast mode.
Note: Simulation speed is not displayed when running a simulation in step-by-step mode (N/A is displayed instead).

%figure "Speedometer"

%end

To the left of the speedometer, the virtual time is displayed using following format:

H:MM:SS:MMM

Where H is the number of hours (may be several digits), MM is the number of minutes, SS is the number of seconds, and MMM is the number of milliseconds (see this figure).
If the speedometer value is greater than one, the virtual time is progressing faster than real time.

The basic time step for simulation can be set in the basicTimeStep field of the WorldInfo node in the scene tree window.
It is expressed in virtual time milliseconds.
The value of this time step defines the length of the time step executed during the Step mode.
This step is multiplied by the displayRefresh field of the same WorldInfo node to define how frequently the display is refreshed.