openvrml::bounding_volume Class Reference

A bounding volume. More...

#include <openvrml/bounding_volume.h>

Inheritance diagram for openvrml::bounding_volume:

List of all members.


Public Types

enum  intersection {
  outside = -1,
  partial = 0,
  inside = 1
}
 Indicates the type of intersection. More...

Public Member Functions

virtual ~bounding_volume ()=0 throw ()
 Destroy.
void maximize ()
 Maximize the bounding volume.
bool maximized () const throw ()
 Indicates whether the bounding volume is maximized.
intersection intersect_frustum (const openvrml::frustum &frustum) const
 Intersect this bounding_volume with a frustum.
void extend (const vec3f &p)
 Extend the bounding volume to enclose p.
void extend (const bounding_volume &bv)
 Extend the bounding_volume to enclose bv.
void enclose (const std::vector< vec3f > &points)
 Enclose the given set of points.
void ortho_transform (const mat4f &M)
 Transform this bounding volume using an orthogonal transfom.
void transform (const mat4f &M)
 Transform this bounding volume using an affine transfom.

Private Member Functions

virtual void do_maximize ()=0
 Called by bounding_volume::maximize.
virtual bool do_maximized () const =0
 Called by bounding_volume::maximized.
virtual intersection do_intersect_frustum (const openvrml::frustum &frustum) const =0
 Called by bounding_volume::intersect_frustum.
virtual void do_extend (const vec3f &p)=0
 Extend the bounding volume to enclose p.
virtual void do_extend (const axis_aligned_bounding_box &bbox)=0
 Called by bounding_volume::extend(const bounding_volume &).
virtual void do_extend (const bounding_sphere &bs)=0
 Called by bounding_volume::extend(const bounding_volume &).
virtual void do_enclose (const std::vector< vec3f > &points)=0
 Called by bounding_volume::enclose.
virtual void do_ortho_transform (const mat4f &M)=0
 Called by bounding_volume::ortho_transform.
virtual void do_transform (const mat4f &M)=0
 Called by bounding_volume::transform.

Detailed Description

A bounding volume.

All the geometry in a scene maintains a bounding volume to help speed up rendering and picking. Although currently we're just using spheres, the plan is to eventually use tighter bounds like axis aligned boxes around nodes that are expected to be static. That probably means boxes for geometry and spheres for grouping nodes.

See also:
openvrml::bounding_sphere

openvrml::axis_aligned_bounding_box


Member Enumeration Documentation

Indicates the type of intersection.

Enumerator:
outside  Indicates that the tested volume is entirely outside the target volume.
partial  Indicates that the tested volume intersects with the target volume.
inside  Indicates that the tested volume is entirely inside the target volume.


Constructor & Destructor Documentation

openvrml::bounding_volume::~bounding_volume (  )  throw () [pure virtual]

Destroy.


Member Function Documentation

void openvrml::bounding_volume::maximize (  ) 

Maximize the bounding volume.

Delegates to bounding_volume::do_maximize.

See also:
maximized

bool openvrml::bounding_volume::maximized (  )  const throw ()

Indicates whether the bounding volume is maximized.

The convention is that nodes that should be rendered unconditionally set a maximum bounding volume, ensuring that the branch they are on does not get pruned during culling. Stuff like the picking code needs a way to differentiate this from just a really big bounding volume, or an unset bounding volume.

Returns:
true if the bounding voume is maximized; false otherwise.
See also:
openvrml::bounding_volume::maximize

openvrml::bounding_volume::intersection openvrml::bounding_volume::intersect_frustum ( const openvrml::frustum frustum  )  const

Intersect this bounding_volume with a frustum.

The test assumes that the frustum is in the canonical looking-down-negative-z orientation, so the bounding volume is going to have to be transformed into the frustum's space. (Alternatives include transforming the frustum into the bvolume's space, or transforming both of them into the projection space. Lots of tradeoffs involved, but transforming the bvolume is probably the simplest approach overall.)

Parameters:
[in] frustum the frustum.
Returns:
inside, outside, or partial.
See also:
openvrml::bounding_volume::transform

openvrml::bounding_volume::ortho_transform

void openvrml::bounding_volume::extend ( const vec3f p  ) 

Extend the bounding volume to enclose p.

Delegates to bounding_volume::do_extend.

Parameters:
[in] p a point

void openvrml::bounding_volume::extend ( const bounding_volume bv  ) 

Extend the bounding_volume to enclose bv.

Delegates to bounding_volume::do_extend(const bounding_sphere &) and bounding_volume::do_extend(const axis_alligned_bounding_box &).

Parameters:
[in] bv a bounding volume.

void openvrml::bounding_volume::enclose ( const std::vector< vec3f > &  points  ) 

Enclose the given set of points.

This resets the volume from any previous values.

Delegates to bounding_volume::do_enclose.

Parameters:
[in] points points.

void openvrml::bounding_volume::ortho_transform ( const mat4f M  ) 

Transform this bounding volume using an orthogonal transfom.

Orthogonal transformations preserve angles. They include translation, rotation, and uniform scaling. It turns out to be so easy to transform bounding spheres by orthogonal transformations that it's worth special casing. The caller is responsible for assuring that the transformation is in fact orthogonal, otherwise the results are undefined. If in doubt, call transform instead and take the speed hit.

Delegates to bounding_volume::do_ortho_transform.

Parameters:
[in] M orthonormal transformation matrix.

void openvrml::bounding_volume::transform ( const mat4f M  ) 

Transform this bounding volume using an affine transfom.

Affine transformations can include nonuniform scaling. It is much messier to deal with them, but VRML allows nonuniform scaling, so we have to handle it. Note that since all orthogonal transforms are affine, it's safe to always call this routine instead of ortho_transform, but it's likely to be slower. The results are undefined if this routine is called with a non-affine argument. Note that VRML Transform nodes only allow affine transformations, so unless you're doing something tricky this routine should always be safe.

Delegates to bounding_volume::do_transform.

Parameters:
[in] M affine transformation matrix.

void openvrml::bounding_volume::do_maximize (  )  [private, pure virtual]

bool openvrml::bounding_volume::do_maximized (  )  const [private, pure virtual]

Called by bounding_volume::maximized.

Returns:
true if the bounding voume is maximized; false otherwise.
See also:
openvrml::bounding_volume::maximized

Implemented in openvrml::bounding_sphere, and openvrml::axis_aligned_bounding_box.

openvrml::bounding_volume::intersection openvrml::bounding_volume::do_intersect_frustum ( const openvrml::frustum frustum  )  const [private, pure virtual]

void openvrml::bounding_volume::do_extend ( const vec3f p  )  [private, pure virtual]

Extend the bounding volume to enclose p.

Parameters:
[in] p a point

Implemented in openvrml::bounding_sphere, and openvrml::axis_aligned_bounding_box.

void openvrml::bounding_volume::do_extend ( const axis_aligned_bounding_box bbox  )  [private, pure virtual]

Called by bounding_volume::extend(const bounding_volume &).

Parameters:
[in] bbox an axis-aligned bounding box.

Implemented in openvrml::bounding_sphere, and openvrml::axis_aligned_bounding_box.

void openvrml::bounding_volume::do_extend ( const bounding_sphere b  )  [private, pure virtual]

Called by bounding_volume::extend(const bounding_volume &).

Parameters:
[in] b a bounding sphere

Implemented in openvrml::bounding_sphere, and openvrml::axis_aligned_bounding_box.

void openvrml::bounding_volume::do_enclose ( const std::vector< vec3f > &  points  )  [private, pure virtual]

Called by bounding_volume::enclose.

Parameters:
[in] points points.

Implemented in openvrml::bounding_sphere, and openvrml::axis_aligned_bounding_box.

void openvrml::bounding_volume::do_ortho_transform ( const mat4f M  )  [private, pure virtual]

Called by bounding_volume::ortho_transform.

Parameters:
[in] M orthonormal transformation matrix in mat4f format

Implemented in openvrml::bounding_sphere, and openvrml::axis_aligned_bounding_box.

void openvrml::bounding_volume::do_transform ( const mat4f M  )  [private, pure virtual]

Called by bounding_volume::transform.

Parameters:
[in] M affine transformation matrix.

Implemented in openvrml::bounding_sphere, and openvrml::axis_aligned_bounding_box.