3D in XAML/C#: Independent Control of Multiple 3D Models

<!-- we have three 3d models, each needs it's own storyboard
for the animations -->
<!-- storyboard for large center cross -->
<BeginStoryboard>
<!-- naming Storyboard lets us refer to it in C# code-behind -->
<Storyboard Name="centerStoryboard"
Storyboard.TargetName="rotation"
RepeatBehavior="Forever">
<!-- rotate the object 360 degrees -->
<DoubleAnimation Storyboard.TargetProperty="Angle"
To="360" Duration="0:0:3" />
</Storyboard>
</BeginStoryboard>

At the bottom of the window I added another Grid, and some nested StackPanels to hold GroupBoxes with RadioButtons to control the axis of rotation for each model, and some command Buttons to Start and Stop the animation, as well as change the camera position to zoom in or out and return to the start position. The animation starts when the Grid is loaded, and for reasons I haven't yet discovered, the Stop animation button will only work after you have pressed the Start button (even though it's already started). I am assuming you know how to use RadioButtons and command Buttons and assign their events like this.

<RadioButton Name="leftXradio" Margin="5"
Checked="leftXradio_Checked">x-axis</RadioButton>

<Button Name="zoomInButton" Margin="5" Width="75"
Click="zoomInButton_Click">Zoom in</Button>

If not you will see it in the XAML code and it's full of comments. The C# code-behind is fairly short and simple. I used some Boolean variables to tell which camera position was being used and some Point3D variables to hold the different camera positions.

// variables to hold camera positions
private Point3D normalPosition;
private Point3D zoomedOutPosition;
private Point3D zoomedInPosition;
// booleans for what view the camera is using
private bool normalView;
private bool zoomedOutView;
private bool zoomedInView;

I set the values for the camera positions, and the events for the RadioButtons and command Buttons change the axis of rotation and camera position. Each cross has a RadioButton to change the the X,Y or Z axis of rotation, and there are 3 buttons to zoom-in, zoom-out and return to the original camera position.

private void setMyValues()
{
normalView = true; // start with normal
zoomedOutView = false;
zoomedInView = false;
// define the camera positions to use
normalPosition = new Point3D(25, 0, 0);
zoomedOutPosition = new Point3D(40, 0, 0);
zoomedInPosition = new Point3D(10, 0, 0);
} // end method setMyValues

I assume you know how to setup RadioButtons and command Buttons and set their events for the C# code-behind file. If not, both the XAML and C# code are commented so you can see what is happening.

// radio buttons for left small cross rotation axis
private void leftXradio_Checked(object sender, RoutedEventArgs e)
{
leftRotation.Axis = new Vector3D(1, 0, 0); // set rotation axis
} // end method leftXradio_Checked
private void zoomInButton_Click(object sender, RoutedEventArgs e)
{
camera.Position = zoomedInPosition; // zoom in 15 units
zoomedOutView = false;
zoomedInView = true;
normalView = false;
} // end method zoomOut_Click

The screenshots below show some of the different rotation combinations. Each of the 3DModels can be independently controlled using the RadioButton in their GroupBox for either the X, Y or Z axis for rotation. All three crosses have the origin (0,0,0) as the reference point for their rotations. It is just as easy to specify a different reference point, for example to have the small crosses rotate at their center point. I forgot to do a screenshot of the zoom-in, zoom-out feature. It changes the camera position from the normal view 25 units away to either 10 units (zoom-in) or 40 units (zoom-out). You will be able to see this when you run the program.

All 3 crosses rotating on the Z axis. Small crosses "orbit" the large one.

Small crosses rotating on X axis, large cross on Y axis.

Left and center cross rotating on X axis, right cross on Y axis.

Z, Y and X rotations. Left small cross "orbits" vertically, right cross horizontally.

Both the XAML code and the C# code-behind file are commented to explain what is going on. With this example you should be able to understand the basics of Model3DGroups, Animation and changing the camera position in your own 3D environment. It was after this that I started writing a 3D maze game, which is almost done. Still trying to figure out how to animate the camera turning. At the moment the left and right turns “snap” to the new direction. But, I will figure it out. I have yet to find a problem I can't solve.

Good luck and have fun with 3D and XAML/C#.

Garry