Build and Connect a Virtual World
This example shows you how to create a simple virtual world using the 3D World Editor. The example does not show everything that you can do with the editor. However, the example does show you how to perform some basic tasks to get started.
This example assumes that you have set your default editor to be the 3D World Editor. For details, see Set the Default Editor.
This example describes the steps to build a simplified version of the virtual world that you see if you enter this command in the MATLAB® command window:
Define the Problem
Suppose that you want to simulate and visualize in virtual reality the deformation of a sphere. In your virtual world, you want to have two boxes representing rigid plates (B1, B2) and an elastic sphere (S) between them. All three of the objects are center-aligned along the x-axis. The boxes B1 and B2 move toward S with identical velocities, but they move in opposite directions. As they reach the sphere S, they start to deform it by reducing its x dimension and stretching both its y and z dimensions.
Here is how this virtual world looks:
The following table lists the positions and dimensions of the objects that you create for this example.
3D Animation™ product includes the tutorial model
vrtut3. This simplified model simulates the deformation of an
elastic sphere. After collision with the rigid blocks, the sphere's x
dimension decreases by a factor from 1 to 0.4. Also, the y and
z dimensions expand to keep the volume of the deformed
sphere-ellipsoid constant. Additional blocks in the model supply the correctly sized vectors
to the Simulink
3D Animation block. The simulation stops when the sphere is deformed to 0.4 times its
original size in the x direction.
Your first task is to open a Simulink model and add a Simulink 3D Animation block to your model.
Add a Simulink 3D Animation Block
This procedure uses the Simulink model
vrtut3 to show how to add a Simulink
3D Animation block to your model. The model generates the values for the position of B1,
the position of B2, and the dimensions of S (as described in Define the Problem).
Open the Simulink 3D Animation™ - Tutorial #3 example.
At the top of the page that opens, select Open Model.
vrtut3file to your MATLAB working folder.
In MATLAB, change the current folder to your MATLAB working folder.
In the MATLAB Command Window, type:
A Simulink window opens with a model that contains Simulink 3D Animation VR Signal Expander blocks, but no VR Sink block to write data from the model to Simulink 3D Animation. Instead, this model uses Scope blocks to monitor temporarily the relevant signals.
From the MATLAB Command Window, type
The Simulink 3D Animation library opens.
From the Library window, drag and drop the VR Sink block to the Simulink diagram. You can then close the Library Browser window.
Your next task is to create a virtual world that you will associate with the VR Sink block. See Open a New Virtual World.
Open a New Virtual World
You must create a virtual world to connect to a Simulink model for visualizing signals.
This procedure opens a new virtual world, in which you add nodes for visualizing the
signals of the model
vrtut3. The connection between the virtual world and
the Simulink model requires that the model includes a VR Sink block, as
described in Add a Simulink 3D Animation Block.
Start the 3D World Editor with an empty virtual world. From the MATLAB Toolstrip, in the Apps tab, in the Simulation Graphics and Reporting section, click 3D World Editor.
The 3D World Editor displays:
In the left pane, a virtual scene tree with only a
In the right pane, an empty virtual world
In the bottom pane, an empty pane for editing objects
You can save the virtual world at any point. Save the virtual world as
vrtut3.x3din the same working folder where your
vrtut3file resides. Do not close the 3D World Editor.
Your next two tasks create a virtual world to use with the
Defining virtual world objects involves defining a hierarchy of nodes. This example
shows how to define
Transform nodes under the
node, with each
Transform node including a hierarchy of
Geometry, and specific shape (in this case, a
In the tree in the left pane, click
ROOT(the topmost item).
Transformnode, using the following sequence of menu selections.
Transformnode is for the B1 box. To name the
Select the Edit Name menu item.
In the edit box to the left of the
Shapenode, using the following sequence of menu selections:
Appearancenode for the Shape node:
Shapenode, select the
Appearancenode, using the following sequence of menu selections.
Materialnode to the
(Appearance)node and select the
Materialnode, using the following sequence of menu selections.
Boxnode to the
geometry(SFNode)node of the
Boxnode, using the following sequence of menu selections.
With all the nodes expanded, the 3D World Editor now displays a box in the virtual world display pane.
Make the box smaller by editing its
sizeproperty of the
In the object properties edit pane at the bottom of the 3D World Editor, enter
0.3in the first column, and
1in the second and third columns.
The box becomes smaller.
Move the box to the right by changing the
translation(SFVec3f)property of the
B1(Transform)node. In the object properties edit pane, set the first column to
3and leave the second and third columns set to
Add a second box that is similar to the first box.
ROOTnode, add a
Transformnode (see step 2) and name it
B2(see step 3).
Shapenode. Under the
B1 Transformnode, right-click the
Shapenode in the
B1 Transformnode and select the Copy menu item.
Paste the copied Shape node into the
B2 Transformnode. Under the
B2 Transformnode), right-click the
childrennode and select the Paste Node > Paste menu item.
B1node collapsed and the
B2node expanded, the 3D World Editor looks like the following graphic.
Move the box that you created to the left by changing the
translationproperty of the
B2(Transform)node. In the object properties edit pane, set the first column to
-3and leave the second and third columns set to
Create a Sphere
Your next task is to add a sphere between the two boxes. This section assumes that you have completed the tasks described in Add Nodes.
To make it easier to focus the tree structure pane on the nodes that you want to add, collapse the
In the tree in the left pane, click
Spherenode. The 3D World Editor includes a library of objects for building a virtual world, including a
Spherelibrary object using the following sequence of menu selections.
From the list of Component Library folders, select the
Shapesfolder, and then select the
Transformnode and name it
S Transformnode fully expanded and the other
Transformnodes collapsed, the 3D World Editor looks like the following graphic.
To make the sphere blue, under the
Materialnode, select the
diffuseColorproperty. In the object properties edit pane, change the first column value to
0.2, the second column to
1, and the third column to
Save the virtual world file.
Your next task is to connect the model outputs to the Simulink 3D Animation block in your Simulink model. See Link to a Simulink Model.
Link to a Simulink Model
This procedure uses the model
vrtut3 as an example. It assumes that
you have opened the model and that you have added a VR Sink block, and that you have
created a virtual world called
vrtut3.x3d. See the tutorial starting
with Add a Simulink 3D Animation Block.
Open the VR Sink Block Parameters dialog box. In the Simulink Editor, double-click the VR Sink block.
Next to the Source file edit box, click Browse.
vrtut3.x3d, and then click Open.
In the Output pane, select Open Viewer automatically. This check box specifies that a viewer for the virtual world starts when you run the model.
For the Description parameter, type
In the VR Sink dialog box, click Apply.
In the tree structure pane, select the B1 translation, B2 translation, and S scale check boxes as the nodes that you want to connect to your model signals. Click OK.
The VR Sink block appears with corresponding inputs.
Delete the three Scope blocks and their associated input signal lines.
Connect the input lines from the two VR Signal Expander blocks and
S Scaling in XYZblock to the appropriate ports in the VR Sink block.
Double-click the VR Sink block.
The viewer appears.
In the viewer, select the Simulation > Block Parameters option. Your default viewer opens and displays the virtual world. For more information on changing your default viewer, see Set the Default Viewer.
In the VR Sink Block Parameters dialog box, click the View button.
In the Simulink Editor, select Simulation > Run.
In your default viewer, you see a 3-D animation of the scene. Using the viewer controls, you can observe the action from various points.
When the width of the sphere is reduced to 0.4 of its original size, the simulation stops running.
This example shows you how to create and use a simple virtual reality model. Using the same method, you can create more complex models for solving the particular problems that you face.