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Page Revision: 2015/10/13 02:17

XAML 3D Viewport element renders a dynamic viewport projection of 3D models stored in the XAML 3D format.

Table of Contents [Hide/Show] Element actions aligned with different epochs of the parent event Properties     Generic Properties Description Loading 3D models     Picking up a XAML 3D template     Importing the XAML 3D files     Editing 3D models Deploying the 3D XAML Viewport element     Creating a single 3D stimulus     Creating a switchable 3D stimulus set Controlling camera settings Animating the camera orbit position Dynamic object tracking Notes

Description ¶

XAML 3D is a sub-branch of the XAML markup language intended for description of 3D models of any level of complexity. In contrast to other 3D formats, XAML 3D allows dynamic adjustments of all 3D model's parameters (e.g. object positions, materials, lighting) via scripting or XAML data binding. (Note that if you want to use static 3D models with a camera control, you may prefer the 3D Viewport element in EventIDE, because the latter supports more common 3D formats, e.g. the Wavefront obj). The XAML 3D viewport element is the best choice for creating 3D animations, interactive 3D scenes and the hittest-based object tracking. Multiple 3D models can be loaded into element's material list to form a switchable 3D stimulus set.

Loading 3D models ¶

Before you deploy the XAML 3D Viewport element, you have to create or import XAML 3D models into Material Library.

Picking up a XAML 3D template ¶

EventIDE provides the XAML template gallery, which includes a number of basic 3D models. Once you select a 3D model in the gallery, it will be added into Material Library. Before adding a model, you can choose its material color. You can find the 3D models in the last row of the template gallery (Library ribbon tab->Add XAML template):

Basic 3D models in the template gallery

Importing the XAML 3D files ¶

XAML 3D models are stored in a special file format supported in several 3D editors:

• Blender (with the free extension by TheRHogue)
• 3D Studio Max (with the free extension by sorskoot)
• Microsoft Blend (visual editor for XAML)
  

You can import existing XAML 3D files into Material Library using the 'Load Materials' command (or, simply dropping the XAML files into the Library panel). If a 3D model has references to external material files, the materials will also be automatically imported.

Examples of the XAML 3D models rendered in an interactive preview panel. Complete model's statistics is shown in the superimposed text blocks.

Editing 3D models ¶

A XAML 3D model is defined by a markup script, which can be previewed and edited in EventIDE. The script is made of a hierarchy of description tags for camera, lighting, materials, transforms and object meshes. You can see a content of the markup script for a cube model on the next screenshot.

Editor for XAML 3D script (click to enlarge). Note the highlighted line that show the data binding syntax. The data binding makes the material color linked to a user variable that can be changed at runtime.

Deploying the 3D XAML Viewport element ¶

Creating a single 3D stimulus ¶

1. Select an event, which will contain a 3D stimulus
2. Add a new 3D XAML Vieweport element and select it in the Elements panel
3. Open Material Library and start dragging a selected 3D model
4. Drop the model over the 3D XAML Vieweport icon in the Elements panel
5. If required, adjust the position and size of the 3D XAML Vieweport on the event surface
6. If required, modify other element's properties (e.g. the camera orbit position) in the Properties panel
   

Creating a switchable 3D stimulus set ¶

1. Repeat the above steps, except that this time you drag multiple 3D models into the 3D XAML Vieweport element.
2. If required, switch the models by the 'Selected Index' or 'Selected Item' properties of the 3D XAML Vieweport element.
   

Controlling camera settings ¶

Beside XAML data binding, the 3D XAML Viewport element enables direct control of camera settings via the element's properties. These properties include the camera position, look-up direction, up direction, near and far plane distance and field of view. Once a new 3D model is selected in the element's material list, these properties receive the initial values defined in the XAML 3D script. If you change the values, the viewport projection is automatically updated.

Animating the camera orbit position ¶

3D animation is often generated by moving a camera over a 3D model. However, beside setting a new camera position on each animation step, you have to also recalculate the camera directions settings relative to the 3D model. The 3D XAML Viewport element offers much easier way to generate 3D animation with the camera orbit rotation. In this type of motion, the camera 'focus' point is fixed at the selected point (usually the coordinate origin) on a 3D model. The camera distance to the focus point is also fixed. To produce animation, you just change the Yaw, Pitch and Roll angles defining the orbital position of camera. The camera orbit angles are represented by the 'Orbit Rotation' property of the 3D XAML Viewport element. The property has a Vector3D data type, in which X,Y and Z fields represent the Yaw, Pitch and Roll angles respectively. For instance, to produce the 'Earth' rotation over a model you can use just one code line:

OrbitRotation.X=OrbitRotation.X+2.5;

When necessary, the camera 'focus' point and distance can be adjusted with 'Orbit Center' and 'Orbit Scale' properties of the 3D XAML Viewport element.

Dynamic object tracking ¶

The 3D XAML Viewport element allows dynamic object tracking with 2D positional input over a projection viewport. Imagine a participant moving a mouse over a viewport. The 3D XAML Viewport element reads the mouse posotion and build a 3D ray orthogonal to the projection (or, camera) plain. If the ray touches any 3D object in the model, the element returns a name of this tracked object, 3D coordinates of touched point on the object surface and the camera-object distance. If the ray penetrates through several objects in the model, the closest object to the camera plane is selected. See the following example of object tracking on a animated 3D scene recorded in EventIDE: Other positional devices, such as eye-trackers, joysticks, etc can also used for the 3D object tracking.

Notes ¶

• To enable the full hardware acceleration for 3D XAML Viewport element rendering, you can turn on the hardware composition mode in properties of the Experiment object.
• 3D Viewport element has faster rendering than 3D XAML Viewport element.