Webots User Guide

previous page go up next page

Foreword

Thanks

1.Installing Webots

2.Upgrading from Webots 2

3.Getting Started with Webots

4.Tutorial: Modelling and simulating your robot

5.Robot and Supervisor Controllers

6.Tutorial: Using the KheperaTM robot

7.ALife Contest

     

3.2 Main Window: menus and buttons

The main window allows you to display your virtual worlds and robots described in the .wbt file. Four menus and a number of buttons are available.

3.2.1 File menu and shortcuts

The New menu item opens a new default world representing a chessboard of 10 x 10 plates on a surface of 1 m x 1 m. The following button can be used as a shortcut:

New

The File menu will also allow you to perform the standard file operations: Open..., Save and Save As..., respectively, to load, save and save with a new name the current world.

The following buttons can be used as shortcuts:

Open...

Save

The Export VRML item allows you to save the .wbt file as a .wrl file, conforming to the VRML 2.0 standard. Such a file can, in turn, be opened with any VRML 2.0 viewer. This is especially useful for publishing a world created with Webots on the Web.

The Revert item allows you to reload the most recently saved version of your .wbt file.

The following button can be used as a shortcut:

Revert

The Preferences item pops up a window with the following panels:

  • General: The Startup mode allows you to choose the state of the simulation when Webots is launched (stop, run, fast; see the Simulation menu).

    The Refresh rate corresponds to the speed of the simulation when Webots is launched.

    The HyperGate port specifies the computer port used for HyperGate networking.

  • Rendering: this tab controls the 3D rendering in the simulation window.

    Checking the Display sensor rays check box displays the distance sensor rays of the robot(s) as red lines.

    Checking the Display lights check box displays the lights (PointLight in the world so that they can be moved more accurately).

  • Files and paths: The default .wbt world which is open when launching Webots and the user directory are defined here. The user directory should contain at least a worlds, controllers, and objects directories where Webots will be looking for files.

3.2.2 Edit menu

The Scene Tree Window item opens the window in which you can edit the world and the robot(s). A shortcut is available by double-clicking on a solid in the world. A solid is a physical object in the world (see subsection 3.3.3).

3.2.3 Simulation menu and the simulation buttons

In order to run a simulation a number of buttons are available corresponding to menu items found under the Simulation menu:

Stop: interrupt Run or Fast modes.

Step: execute one simulation step.

Run: execute simulation steps until the Stop mode is entered.

Fast: same as Run, except that no display is performed.

The Fast mode performs a very fast simulation mode suited for heavy computation (genetic algorithms, vision, learning, etc.). However, as the world display is disabled during a Fast simulation, the scene in the world window stays blank until the Fast mode is stopped.

The World View / Robot View item allows you to switch between two different points of view:

  • World View: this view corresponds to a fixed camera standing in the world.

  • Robot View: this view corresponds to a mobile camera following a robot.

The default view is the world view. If you want to switch to the Robot View, first select the robot you want to follow (click on the pointer button then on the robot), and then choose Robot View in the Simulation menu. To return to the World View mode, reselect this item.

A speedometer (see figure 3.2) allows you to observe the speed of the simulation on your computer. It 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 relevant both in Run mode and Fast mode.

speedometer

Figure 3.2: Speedometer

The time step can be chosen from the popup menu situated next to the speedometer. It indicates how frequently the display is refreshed. It is expressed in virtual time milliseconds. The value of this time step also defines the duration of the time step executed during the Step mode. The time step can be chosen from the popup menu situated next to the speedometer. It indicates how frequently the display is refreshed. It is expressed in virtual time milliseconds. The value of this time step also defines the duration of the time step executed during the Step mode.

In Run mode, with a time step of 64 ms and a fairly simple world displayed with the default window size, the speedometer will typically indicate approximately 0.5 on a Pentium II / 266 without hardware acceleration and 4 on an Ultra Sparc 10 Creator 3D.

3.2.4 Help menu

In the Help menu, the About... item opens the About... window, displaying the license information.

The Introduction item is a short introduction to Webots (HTML file). You can access the User Guide and the Reference Manual with the User Guide and Reference Manual items (PDF files). The Web site of Cyberbotics item lets you visit our Web site.

3.2.5 Navigation in the scene

The view of the scene is generated by a virtual camera set in a given position and orientation. You can change this position and orientation to navigate in the scene using the mouse buttons. The x, y, z axes mentioned below correspond to the coordinate system of the camera; z is the axis corresponding to the direction of the camera.

  • Rotate viewpoint: To rotate the camera around the x and y axis, you have to click on the left mouse button in the scene and then:

    if you click on a solid object and drag the mouse in the scene, the rotation will be centered around the origin of the local coordinate system of this solid object.

    if you click outside of any solids and drag the mouse the rotation will be centered around the origin of the world coordinate system.

  • Translate viewpoint: To translate the camera in the x and x directions, you can click the right mouse button and drag the mouse on the scene.

  • Zoom / Tilt viewpoint: set the mouse over the scene, then:

    if you click on the middle button and drag the mouse vertically, the camera will zoom in or out.

    if you click on the middle button and drag the mouse horizontally, the camera will rotate around its z axis.

    if you use the wheel of the mouse, the camera will zoon in or out.

    if you have a two-button mouse, hold down the control key while pressing the left mouse button to be able to zoom in the scene.

3.2.6 Moving a solid object

In order to move object, hold the shift key down while using the mouse.

  • Translation: Pressing the left mouse button while the shift key is pressed allows you to drag solid objects on the ground ($xz$ plan).

  • Rotation: Pressing the right mouse button while the shift key is pressed rotates solid objects: a first click is necessary to select a solid object, then a second click-and-drag rotates the selected object around its $y$ axis.

  • Lift: Pressing the middle mouse button (or rolling the mouse wheel) while the shift key is pressed allows you to lift up or down the selected solid object. If you have a two-button mouse, you will need to hold down both the shift and control keys to lift solid objects.

3.2.7 Selecting a solid object

Simply clicking on a solid object allows you to select this object. Selecting a robot enables the choice of Robot View in the simulation menu. Double-clicking on a solid object opens the scene tree window where the world and robots can be edited. The selected solid object appears selected in the scene tree window as well.

previous page go up next page
^ page top ^

  E-mail to webmaster Last updated: Copyright © 2002 Cyberbotics Ltd.