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/*!
\class SbProjector SbProjector.h Inventor/projectors/SbProjector.h
\brief The SbProjector class is the abstract base projector class.
\ingroup projectors
Projectors are used in the Coin library for mapping 2D coordinates
(typically from the position of the mouse cursor in the rendering
window) to 3D "world" coordinates.
Mapping 2D coordinates to 3D coordinates is something which is done
extensively in the dragger classes, to provide the user with a
convenient and natural way of interacting with the 3D geometry of
scenes.
For a usage example, see the class documentation for
SbSphereSheetProjector.
The application programmer should normally not need to care about
the projector classes, unless there are special needs in the
application.
\sa SoDragger
*/
#include
#include
#include
#include
#include
#include "coindefs.h"
/*!
\fn SbProjector::~SbProjector()
Destructor is protected, as this is an abstract class.
*/
/*!
\fn virtual SbVec3f SbProjector::project(const SbVec2f & point)
Project the 2D \a point from normalized viewport coordinates to a 3D
point. The mapping will be done in accordance with the type of the
projector.
*/
/*!
\fn virtual SbProjector * SbProjector::copy(void) const
Construct and return a copy of this projector. The caller is
responsible for destructing the new instance.
\DANGEROUS_ALLOC_RETURN
*/
/*!
\var SbProjector::viewVol
The viewVol definition.
*/
/*!
\var SbProjector::worldToWorking
The matrix which converts from world coordinates to coordinates in
the projector's local coordinate system.
*/
/*!
\var SbProjector::workingToWorld
The matrix which converts from coordinates in the projector's local
coordinate system to world coordinates.
*/
/*!
The constructor initializes the workingspace matrix to an identity
matrix.
*/
SbProjector::SbProjector(void)
{
this->worldToWorking.makeIdentity();
this->workingToWorld.makeIdentity();
}
/*!
Set the viewing volume the projections will take place in.
\sa getViewVolume()
*/
void
SbProjector::setViewVolume(const SbViewVolume & vol)
{
this->viewVol = vol;
}
/*!
Return the current viewing volume used by the projections.
\sa setViewVolume()
*/
const SbViewVolume &
SbProjector::getViewVolume(void) const
{
return this->viewVol;
}
/*!
Sets the matrix used for converting from the projector's coordinate
system to the world coordinate system.
*/
void
SbProjector::setWorkingSpace(const SbMatrix & space)
{
this->workingToWorld = space;
this->worldToWorking = space.inverse();
}
/*!
Returns projector-to-world matrix.
\sa setWorkingSpace()
*/
const SbMatrix &
SbProjector::getWorkingSpace(void) const
{
return this->workingToWorld;
}
/*!
From the 2D \a point in normalized screenspace coordinates,
calculate the line passing through the scene.
Typically used for tracking intersection points for the mouse
cursor.
*/
SbLine
SbProjector::getWorkingLine(const SbVec2f & point) const
{
SbLine l;
this->viewVol.projectPointToLine(point, l);
this->worldToWorking.multLineMatrix(l, l);
return l;
}
/*!
Finds the unit cube vanishing distance for the current projector
view volume. The view volume must be a perspective view
volume.
This method was not part of the Inventor v2.1 API, and is an
extension specific to Coin.
\since Coin 1.1
*/
float
SbProjector::findVanishingDistance(void) const
{
const SbViewVolume & vv = this->viewVol;
// FIXME: find a proper algorithm to calculate the vanishing
// distance. Now we just use an incremental algorithm to detect when
// the projected box is less than one pixel on a screen with height
// = 512 pixels. pederb, 2001-10-11
assert(vv.getProjectionType() == SbViewVolume::PERSPECTIVE);
float depth = vv.getHeight();
// used to break out if we get too many iterations. Will probably
// never happen, but it's here just in case something bad happens.
int cnt = 0;
float unit = depth * 0.25f;
SbBox3f unitbox(-unit, -unit, -unit, unit, unit, unit);
SbVec3f projdir = this->viewVol.getProjectionDirection();
SbMatrix m;
m.setTranslate(projdir * depth);
SbBox3f box = unitbox;
box.transform(m);
SbVec2f siz = vv.projectBox(box);
while (cnt < 64 && (siz[1] > (1.0f / 512.0f))) {
depth *= 2.0f;
m.setTranslate(projdir * depth);
SbBox3f box = unitbox;
box.transform(m);
siz = vv.projectBox(box);
cnt++;
}
return depth;
}
/*!
Verifies that \a projpt is a valid projection for the current view
volume. For perspective view volumes, it does this by checking that
the projection point is in front of the eye plane. For orthographic
projections, this method always returns \e TRUE.
This method was not part of the Inventor v2.1 API, and is an
extension specific to Coin.
\since Coin 1.1
*/
SbBool
SbProjector::verifyProjection(const SbVec3f & projpt) const
{
if (this->viewVol.getProjectionType() == SbViewVolume::PERSPECTIVE) {
SbPlane eyeplane = this->viewVol.getPlane(0.0f);
SbVec3f wrld;
this->workingToWorld.multVecMatrix(projpt, wrld);
if (eyeplane.isInHalfSpace(wrld)) return FALSE;
}
return TRUE;
}
/*!
Try projecting the 2D \a point from normalized viewport coordinates to a 3D
point. The mapping will be done in accordance with the type of the
projector.
If the projection can't be done safely (for instance when the
projection plane or line is parallel to the view volume projection),
this function should return FALSE.
Default implementation will call project() and always return TRUE,
but subclasses can override this behavior to support safe
projections.
\since Coin 3.0
*/
SbBool
SbProjector::tryProject(const SbVec2f & point, const float COIN_UNUSED_ARG(epsilon), SbVec3f & result)
{
result = this->project(point);
return TRUE;
}