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Collision Detection with Open Inventor

Open Inventor 2.4 now supports collision detection. It is now possible to manage objects and camera transformations while preventing objects to cross each other. Walls are really walls: you can avoid walking through them. Solid objects are really solid: you can avoid merging them.

Three new classes are provided to support detection of collisions in Open Inventor 2.4.

Viewer collision detection

This method prevents the camera from crossing walls or floors making viewer manipulation much more comfortable and realistic. To use this class, first create a standard viewer and then a SoXtCollisionViewer for this viewer. Collision detection will be activated immediately. The minimum distance between the camera and the object can be tuned. A user callback function can be set to receive a notification when a collision is detected. See SoXtCollisionViewer for more information. A program demonstrates how to use this class: $OIVHOME/src/TGSdemos/ Collision/Viewer

Collision manager

This class is useful to monitor the transformations of an object relatively to a scene graph. It can prevent this object from being in collision with other shapes of the scene or it can glue the object on the surface of the shapes it is in collision with or it can just call a user callback function. The gluing process tries to find the closest position where the objects do not collide. The number of positions to try can be tuned. Collision detection can be computed only on bounding boxes for the object or for the whole scene shapes. When a bounding box collision occurs between two shapes, a user filter function is called. This function can stop the detection process for these two shapes. The second step of the collision detection mechanism consists in comparing each triangle of both shapes. If a triangle collision is found, the collision manager calls the user callbacks. Each callback is able to inform the manager if it is interested in the next collision report for the current transformation. It can be informed of the collision for the next graphic primitive or only for the next shapes or it can just say that it is not interested in the next collision reports for the current transformation. Collisions are detected even if objects are not visible or not pickable. See SoCollisionManager for more information. Two programs demonstrate how to use this class: $OIVHOME/src/TGSdemos/ Collision/Dart and $OIVHOME/src/TGSdemos/Collision/ObjectMoving

Intersection Detection Action

This class is an Open Inventor action. It allows programmers to analyze a complete scene graph to detect intersection between shapes. The action first detects intersection between bounding boxes. If such intersection exists between two shapes, the action calls a user filter function. This function can stop the detection process for these two shapes. The second step of the intersection detection mechanism consists in comparing each triangle of both shapes. If a triangle collision is found, the action calls the user callbacks. Each callback is able to inform the action if it is interested in the next collision report. It can be informed of the intersection for the next graphic primitive or only for the next shapes or it can just say that it is not interested in the next intersection. Intersections are detected even if objects are not visible or not pickable. See SoIntersectionDetectionAction for more information. A program demonstrates how to use this class: $OIVHOME/src/TGSdemos/ Collision/Intersection

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Collision Detection with Open Inventor