AI_SDB_OcclusionVisitor Class Reference
#include <AI_SDB_VisitorBase.h>
Detailed Description
Visitor to collect occluders and provide visibility testing using those occluders.The OcclusionVisitor is a general visitor class that processes occluders and construct some sort of occlusiong representation so that it can determine if other objects are occluder or not. This may be acheived by simply recording all the occluding objects and doing a geometrical inspection of potentially visible objects, or it may be acheive with occlusion maps or some other method. The keys attributes of the occlusion visitor are:
1. Non-compiled. You can add an occluder, test to see if an object is occluded so far, and then add another occluder. If the occlusion determination needs to compile some sort of internal data, it must be able to do so multiple times; there is no requirement to add all the occluders and then start doing occlusion tests. This means you may need to have a flag that forces a recompilation of internal data structures whenever a new occluder is added.
2. Conservative. If the occlusion determination is not sure a given object is totally occluded, it should consider an object visible. A specific occlusion method can do "aggressive culling" and remove objects that are possibly or partially visible, but this should be noted in the documentation. Also, the degree of aggressive culling should be controllable through some user parameters.
3. Deterministic. If I perform an occlusion test on and object, and then do another occlusion test on that same object, it should return the same result unless I have modified the occlusion state (for instance, by adding another occluder). However, if I reset the occlusion state and add in all the same occluders again, you can return a different result. This allows the use of temporal coherence if you really want it.
This visitor doesn't put any spatial bounds on the occluders it will use. If you only want occluders in a specific region--such as a view frustum--you will have to provide a properly configured AI_SDB_VisibilityVisitor using SetVisibilityVisitor. Then potential occluding objects are checked against the visibilitytest() of the visibilityvisitor. The occlusion visitor will tell it's restricting visibility visitor about local space enter/leave events.
Public Member Functions | |
| AI_SDB_OcclusionVisitor (const AI_Vector3 &viewpoint) | |
| virtual | ~AI_SDB_OcclusionVisitor () |
| void | SetRestrictingVisitor (AI_SDB_VisibilityVisitor *vv) |
| virtual void | AddBBoxOccluder (const AI_BBox &boxoccluder)=0 |
| Add an occluder shape like an AABB to the occluding set. | |
| virtual void | AddSphereOccluder (const AI_Sphere &sphereoccluder)=0 |
| Add an occluder shaped like a AI_Sphere to the occluding set. | |
| virtual void | AddHullOccluder (const AI_SDB_PlaneClipper &hulloccluder)=0 |
| Add an occluder shaped like a convex hull (represented by a set of halfspaces) to the occluding set. | |
| virtual AI_SDB_VisitorFlags | VisibilityTest (const AI_BBox &testbox, AI_SDB_VisitorFlags flags)=0 |
| Test of a given object AABB is visible or occluded. | |
| virtual AI_SDB_VisitorFlags | VisibilityTest (const AI_Sphere &testsphere, AI_SDB_VisitorFlags flags)=0 |
| Test of a given object AI_Sphere is visible or occluded. | |
Protected Attributes | |
| AI_SDB_VisibilityVisitor * | m_restrictingvisitor |
Constructor & Destructor Documentation
| AI_SDB_OcclusionVisitor::AI_SDB_OcclusionVisitor | ( | const AI_Vector3 & | viewpoint | ) |
| AI_SDB_OcclusionVisitor::~AI_SDB_OcclusionVisitor | ( | ) | [virtual] |
Member Function Documentation
| void AI_SDB_OcclusionVisitor::SetRestrictingVisitor | ( | AI_SDB_VisibilityVisitor * | vv | ) | [inline] |
| virtual void AI_SDB_OcclusionVisitor::AddBBoxOccluder | ( | const AI_BBox & | boxoccluder | ) | [pure virtual] |
Add an occluder shape like an AABB to the occluding set.
Implemented in AI_SDB_GeometryOcclusionVisitor.
| virtual void AI_SDB_OcclusionVisitor::AddSphereOccluder | ( | const AI_Sphere & | sphereoccluder | ) | [pure virtual] |
Add an occluder shaped like a AI_Sphere to the occluding set.
Implemented in AI_SDB_GeometryOcclusionVisitor.
| virtual void AI_SDB_OcclusionVisitor::AddHullOccluder | ( | const AI_SDB_PlaneClipper & | hulloccluder | ) | [pure virtual] |
Add an occluder shaped like a convex hull (represented by a set of halfspaces) to the occluding set.
Implemented in AI_SDB_GeometryOcclusionVisitor.
| virtual AI_SDB_VisitorFlags AI_SDB_OcclusionVisitor::VisibilityTest | ( | const AI_BBox & | testbox, | |
| AI_SDB_VisitorFlags | flags | |||
| ) | [pure virtual] |
Test of a given object AABB is visible or occluded.
Implements AI_SDB_VisibilityVisitor.
Implemented in AI_SDB_GeometryOcclusionVisitor.
| virtual AI_SDB_VisitorFlags AI_SDB_OcclusionVisitor::VisibilityTest | ( | const AI_Sphere & | testsphere, | |
| AI_SDB_VisitorFlags | flags | |||
| ) | [pure virtual] |
Test of a given object AI_Sphere is visible or occluded.
Implements AI_SDB_VisibilityVisitor.
Implemented in AI_SDB_GeometryOcclusionVisitor.
Member Data Documentation
The documentation for this class was generated from the following files: