Attributes and Behaviors of Primitives - Essentials of Interactive Computer Graphics - page 177

void CModel::UpdateSimulation() {
. // check if primitive is going out of world bound

// Get the bounding volumes ready for collision detection
const UWB _ BoundingVolume * pCircleBV = m _ Circle.GetBoundingVolume(lod);
const UWB _ BoundingVolume * pPointBV

= m _ Point.GetBoundingVolume(lod);

const UWB _ BoundingVolume * pLineBV = m _ Line.GetBoundingVolume(lod);

.
// Colliding circle and point
if (pCircleBV && pPointBV && pCircleBV->Intersects( * pPointBV))
m _ Circle.CollisionResponse(&m _ Point, ptLoc); // circle to response
m _ Point.CollisionResponse(&m _ Circle, cirLoc); // point to response
// Colliding circle and line
if (pCircleBV && pLineBV && pCircleBV->Intersects( * pLineBV)) ...
// Colliding line and point
if (pPointBV && pLineBV && pPointBV->Intersects( * pLineBV)) ...
. // update the position of each object

Source file.
Model.cpp file in the

Model folder of the

D3D _ Collisions project.

Listing 7.20. The CModel::UpdateSimulation() function (Tutorial 7.3).

Working with the collision functionality. With the collision functionality sup-
ported by the library, the source code of Tutorial 7.3 differs from that of Tuto-
rial 7.2 only in the CModel::UpdateSimulation() function. Listing 7.20 shows
that during periodic timer updates, we must intersect all primitive objects against
each other to ensure that we have tested all the potential collisions.

7.6 Collection of Primitives

Tutorial 7.4.
Project Name:
D3D _ ObjectCollections
Library Support:
UWBGL _ MFC _ Lib1
UWBGL _ D3D _ Lib7

From Listing 7.20, it is obvious that we need some form of collection structure
such that we can use a loop programming construct to iterate through each primi-
tive to test for the collision between all the primitives.

Tutorial 7.4. Primitive List

• Goals. To introduce the idea of having a collection structure itself be a
Primitive ; experience working with such structures.