Advanced Blender commands

This section provides further instructions on how to use Blender to setup simulation scenarios.

Note

The Blender interface is divided in various panels (windows). The mouse and keyboard shortcuts used change depending on the panel over which the mouse pointer is located.

Viewing the scene

Follow these recommendations to better visualise a simulation scenario. Before launching a simulation:

  • Select the Blender Game context, on the menu bar at the top of the Blender window. This will affect the information you can change on other panels.
../../_images/configure_display-1.1.png
  • On a Properties window, select the Render panel. To make sure all the screen space in a 3D View window is used, select the Extend option for Framing.
  • To properly display the textures of objects, and to be able to get images from simulated cameras, Blender needs to be set to render using GLSL. This can be selected in the Properties >> Render >> Shading.
../../_images/configure_display-2.2.png
  • To maximise the size of a 3D View window, press Ctrl-Up while the mouse pointer this window.

Physics

Configuring physics properties for objects in a scene can be done in the Properties >> Physics panel. Here it is possible to change the simulation for the selected object. The most useful settings are:

  • No Collision: All objects can occupy the same space as this one, and will not trigger any kind of event when in contact.
  • Static: The object will not move even when in contact with other objects, but is considered as an obstacle.
  • Dynamic: The object is subject to forces and collisions, but will not turn realistically.
  • Rigid Body: The object will behave accordingly to its shape.

Another property that can be toggled is the Actor flag. Only objects with this flag and a Collision Bound will be considered by some of the sensors

For Dynamic and Rigid Body objects, it is possible to define further properties, most importantly their mass and Collision Bounds. The mass will determine the force required to make the object move. Collision Bounds can be selected from a predefined list of shapes, or set to the convex hull of the mesh.

../../_images/configure_display-3.3.png

Logic Bricks

The Logic Editor window can be used to give behaviour to different objects in the scene. This is done using three different kind of blocks, called Sensors, Controllers and Actuators (NOTE: This is different to the robotics components provided by MORSE). By combining this three types of blocks, objects can react to certain events and produce an action in response.

An explanation of all the different options available for configuring the Logic Bricks can be found here.

In this panel it is also possible to add Game Properties to objects, which are variables that can be accessed by Python scripts during the execution of the simulation. Properties can be used to store information about objects. In many cases, MORSE uses these variables to identify different types of objects.

Selecting a robot and all its components

This operation is tricky, and is much easier if the Blender interface has at least a 3D View and an Outliner panel. Follow these steps:

  • Select the robot from the Outliner list, using the Left Mouse Button
  • Move the mouse over to the 3D View panel
  • Press Shift-G, then press enter. This should choose the first option: ‘Children’
  • Move the mouse back to the Outliner panel
  • Hold the Shift key, while selecting the robot again with the Left Mouse Button

The two main operations that require selecting the robot and all of its components are:

  • Delete the robot: Press X and then enter.
  • Duplicate the robot: Press Shift-D and then move the new copy with the mouse. Select the desired position of the copy by pressing the Left Mouse Button

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