H3D::Collision Class Reference
[X3D node classes.]

The Collision node is a grouping node that specifies the collision detection properties for its children (and their descendants), specifies surrogate objects that replace its children during collision detection, and sends events signalling that a collision has occurred between the avatar and the Collision node's geometry or surrogate. More...

#include <H3D/Collision.h>

Inheritance diagram for H3D::Collision:

Inheritance graph

List of all members.

Public Member Functions

 Collision (Inst< MFChild > _addChildren=0, Inst< MFChild > _removeChildren=0, Inst< SFBool > _enabled=0, Inst< MFChild > _children=0, Inst< SFNode > _metadata=0, Inst< SFTime > _collideTime=0, Inst< SFBool > _isActive=0, Inst< SFBound > _bound=0, Inst< SFVec3f > _bboxCenter=0, Inst< SFVec3f > _bboxSize=0, Inst< SFChild > _proxy=0)
 Constructor.
virtual bool lineIntersect (const Vec3f &from, const Vec3f &to, LineIntersectResult &result)
 Detect intersection between a line segment and a Node.
virtual void closestPoint (const Vec3f &p, NodeIntersectResult &result)
 Find closest point on Node to p.
virtual bool movingSphereIntersect (H3DFloat radius, const Vec3f &from, const Vec3f &to, NodeIntersectResult &result)
 Detect collision between a moving sphere and the Node.

Public Attributes

auto_ptr< SFTimecollideTime
 TODO: implement this field.
auto_ptr< SFChildproxy
 The collision proxy, defined in the proxy field, is any legal children node as described in 10.2.1 Grouping and children node types that is used as a substitute for the Collision node's children during collision detection.

Static Public Attributes

static H3DNodeDatabase database
 The H3DNodeDatabase for this node.


Detailed Description

The Collision node is a grouping node that specifies the collision detection properties for its children (and their descendants), specifies surrogate objects that replace its children during collision detection, and sends events signalling that a collision has occurred between the avatar and the Collision node's geometry or surrogate.

By default, all geometric nodes in the scene are collidable with the viewer except IndexedLineSet and PointSet. Browsers shall detect geometric collisions between the avatar (see NavigationInfo) and the scene's geometry and prevent the avatar from 'entering' the geometry. See 23.2.4 Collision detection and terrain following for general information on collision detection.

If there are no Collision nodes specified in a X3D file, browsers shall detect collisions between the avatar and all objects during navigation.

The Collision node's enabled field enables and disables collision detection as well as terrain following when the navigation type requires it. If enabled is set to FALSE, the children and all descendants of the Collision node shall not be checked for collision or terrain, even though they are drawn. This includes any descendent Collision nodes that have enabled set to TRUE (i.e., setting enabled to FALSE turns collision off for every child node below it).

The value of the isActive field indicates the current state of the Collision node. An isActive TRUE event is generated when a collision occurs. An isActive FALSE event is generated when a collision no longer occurs.

Collision nodes with the enabled field set to TRUE detect the nearest collision with their descendent geometry (or proxies). When the nearest collision is detected, the collided Collision node sends the time of the collision through its collideTime field. If a Collision node contains a child, descendant, or proxy (see below) that is a Collision node, and both Collision nodes detect that a collision has occurred, both send a collideTime event at the same time. A collideTime event shall be generated if the avatar is colliding with collidable geometry when the Collision node is read from a X3D file or inserted into the transformation hierarchy.

The bboxCenter and bboxSize fields specify a bounding box that encloses the Collision node's children. This is a hint that may be used for optimization purposes. The results are undefined if the specified bounding box is smaller than the actual bounding box of the children at any time. A default bboxSize value, (-1, -1, -1), implies that the bounding box is not specified and if needed shall be calculated by the browser. More details on the bboxCenter and bboxSize fields can be found in 10.2.2 Bounding boxes..

The collision proxy, defined in the proxy field, is any legal children node as described in 10.2.1 Grouping and children node types that is used as a substitute for the Collision node's children during collision detection. The proxy is used strictly for collision detection; it is not drawn.

If the value of the enabled field is TRUE and the proxy field is non-NULL, the proxy field defines the scene on which collision detection is performed. If the proxy value is NULL, collision detection is performed against the children of the Collision node. If proxy is specified, any descendent children of the Collision node are ignored during collision detection. If children is empty, enabled is TRUE, and proxy is specified, collision detection is performed against the proxy but nothing is displayed. In this manner, invisible collision objects may be supported.

The collideTime field generates an event specifying the time when the avatar (see 23.3.4 NavigationInfo) makes contact with the collidable children or proxy of the Collision node. An ideal implementation computes the exact time of collision. Implementations may approximate the ideal by sampling the positions of collidable objects and the user. The NavigationInfo node contains additional information for parameters that control the avatar size.


Member Function Documentation

void Collision::closestPoint ( const Vec3f &  p,
NodeIntersectResult &  result 
) [virtual]

Find closest point on Node to p.

Calls closestPoint for all children if the node is enabled.

Parameters:
p The point to find the closest point to.
result A struct containing various results of closest points such as which geometries the closest points where detected on.

Reimplemented from H3D::X3DGroupingNode.

References H3D::Node::closestPoint(), and proxy.

bool Collision::lineIntersect ( const Vec3f &  from,
const Vec3f &  to,
LineIntersectResult &  result 
) [virtual]

Detect intersection between a line segment and a Node.

Calls lineIntersect for all children if the Node is enabled.

Parameters:
from The start of the line segment.
to The end of the line segment.
result Contains info about the closest intersection for every object that intersects the line.
Returns:
true if intersected, false otherwise.

Reimplemented from H3D::X3DGroupingNode.

References H3D::Node::lineIntersect(), and proxy.

bool Collision::movingSphereIntersect ( H3DFloat  radius,
const Vec3f &  from,
const Vec3f &  to,
NodeIntersectResult &  result 
) [virtual]

Detect collision between a moving sphere and the Node.

Calls movingSphereIntersect for all children if the node is enabled.

Parameters:
radius The radius of the sphere
from The start position of the sphere
to The end position of the sphere.
result A struct containing various results of intersections such as which geometries intersected the moving sphere.
Returns:
true if intersected, false otherwise.

Reimplemented from H3D::X3DGroupingNode.

References collideTime, H3D::X3D::Convert::getValue(), H3D::Node::movingSphereIntersect(), proxy, and H3D::Scene::time.


Member Data Documentation

TODO: implement this field.

The collideTime field generates an event specifying the time when the avatar (see NavigationInfo) makes contact with the collidable children or proxy of the Collision node.

Access type: outputOnly

Referenced by movingSphereIntersect().

The collision proxy, defined in the proxy field, is any legal children node as described in 10.2.1 Grouping and children node types that is used as a substitute for the Collision node's children during collision detection.

The proxy is used strictly for collision detection; it is not drawn.

Access type: inpuOutput
Default value: NULL

Referenced by closestPoint(), lineIntersect(), and movingSphereIntersect().


The documentation for this class was generated from the following files:

Generated on Fri Nov 7 10:29:28 2008 for H3D API by  doxygen 1.5.7