Graphics Reference
In-Depth Information
B
oc
la
B
oc
Axis-aligned
bounding boxes
in WC
in WC
la
in OC
M
la
WC
Transformed
to WC
OC of
Left Arm
B
wc
B
wc
la
B
o
b
in OC
M
b
B
o
b
in WC
Transformed
to WC
B
w
b
OC of
Body
Figure 11.21.
Coordinate transformations of scene node bounding boxes.
class
UWB
_
SceneNode {
.
Source file.
uwbgl
_
SceneNode2.h
file
in the
Common Files/ Sce-
neNode
UWB
_
BoundingBox GetBounds(...)
const
;
// Compute a Bounding Box in WC space that encloses all the
// primitives of this node including that of all children nodes
A:
subfolder
of
the
UWBGL
_
D3D
_
Lib12
project.
bool
GetNodeBounds(
const
UWB
_
SceneNode
*
pSearchNode ...)
const
;
//
pSearchNode
is a children of this node, this function
// computes a Bounding Box in WC space that encloses all the
// primitives of pSearchNode including that of all it children
// nodes
B:
}
Listing 11.12.
The
SceneNode
bounding box support.
To compute the WC bounding box for this hierarchy, we invoke the
GetBounds()
function of the body node:
•
Compute bounding box in OC (A).
At label A, the OC bounding box
B
oc
b
is computed.
•
Compute OC-to-WC transformation (B).
At label B, the
M
b
matrix is
concatenated to the top of the matrix stack. At this point, the top of the
matrix stack contains the OC-to-WC transformation matrix.
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