Hierarchical Modeling - Essentials of Interactive Computer Graphics - page 293

This tutorial demonstrates how to subclass from the SceneNode class to create
general graphical objects that can be reused. As will be demonstrated in later
tutorials, we can instantiate multiple CArm objects in more complex graphical
models.

Tutorial 11.5. The SceneTreeControl GUI Object

Tutorial 11.5.
Project Name:
D3D _ SceneNodeMultiPrim
Library Support:
UWB_MFC_Lib1
UWB_D3D_Lib11

• Goal. Demonstrate that it is possible to include multiple primitives in a
SceneNode and examine the effects of changing transformation parameters
in a scene node hierarchy.

• Approach. Increase the primitive complexity of the arm's model and in-
troduce the CSceneTreeControl class to support general user interaction
with scene nodes.

Figure 11.7 is a screenshot of running Tutorial 11.5. Compared to the previous
tutorial, the two main differences are: (1) the more complex arm/palm design, and
(2) the more elaborate user interface.

Figure 11.7.

Tutorial

Figure 11.8 shows the detailed design of the arm/palm objects of this tutorial.
In this case, the palm object consists of two primitives ( C p 0 , R p 1 ), and the arm
object has three primitives ( R a 0 , R a 1 , R a 2 ).

11.5.

R a2

R a1

Figure 11.9 shows the SceneNode

R p1

P a

implementation of the design.
With the scene node hierarchy from Figure 11.9, this tutorial implements the
SceneTreeControl GUI container to support user interaction with the different
scene nodes and primitives. As illustrated in Figure 11.10, the SceneTreeControl
itself contains two GUI containers, the PrimitiveControl and XformInfo
Control . Together, these GUI containers support the following

R a0 C p0

Figure 11.8. Design of
the arm of Tutorial 11.5.

• Selection of SceneNode . Displays the tree structure of a SceneNode .A
user can click on any of the nodes in the displayed tree structure to select a
current SceneNode .

Arm

M a

Xform
V
PrimList
Child SN

R a0

R a1 R a2

• Selection of primitive. Allows a user to select a current primitive from the
primitive list of the currently selected SceneNode by scrolling the slider bar
at the bottom of the SceneTreeControl .

M p

Palm

Xform
V
PrimList
Child SN

R p1

C p0 C

• Control of transformation. Through the XformInfoControl GUI con-
tainer, controls the XformInfo transformation operator of the selected Scene
Node .

Figure 11.9. SceneNode
structure for Tutorial 11.5.

• Control of primitive attributes. Through the PrimitiveControl GUI
container, controls the attributes of the selected primitive.