NAME
SbRotation -
The SbRotation class represents a rotation in 3D space.
SbRotation is used extensively throughout the Coin library.
SYNOPSIS
#include <Inventor/SbLinear.h>
Public Member Functions
SbRotation (void)
SbRotation (const SbVec3f &axis, const float radians)
SbRotation (const float q[4])
SbRotation (const float q0, const float q1, const float q2, const float
q3)
SbRotation (const SbMatrix &m)
SbRotation (const SbVec3f &rotateFrom, const SbVec3f &rotateTo)
const float * getValue (void) const
void getValue (float &q0, float &q1, float &q2, float &q3) const
SbRotation & setValue (const float q0, const float q1, const float q2,
const float q3)
void getValue (SbVec3f &axis, float &radians) const
void getValue (SbMatrix &matrix) const
SbRotation & invert (void)
SbRotation inverse (void) const
SbRotation & setValue (const float q[4])
SbRotation & setValue (const SbMatrix &m)
SbRotation & setValue (const SbVec3f &axis, const float radians)
SbRotation & setValue (const SbVec3f &rotateFrom, const SbVec3f
&rotateTo)
SbRotation & operator*= (const SbRotation &q)
SbRotation & operator*= (const float s)
SbBool equals (const SbRotation &r, const float tolerance) const
void multVec (const SbVec3f &src, SbVec3f &dst) const
void scaleAngle (const float scaleFactor)
void print (FILE *fp) const
Static Public Member Functions
static SbRotation slerp (const SbRotation &rot0, const SbRotation
&rot1, float t)
static SbRotation identity (void)
Friends
int operator== (const SbRotation &q1, const SbRotation &q2)
int operator!= (const SbRotation &q1, const SbRotation &q2)
SbRotation operator* (const SbRotation &q1, const SbRotation &q2)
Detailed Description
The SbRotation class represents a rotation in 3D space.
SbRotation is used extensively throughout the Coin library.
An SbRotation is stored internally as a quaternion for speed and
storage reasons, but inquiries can be done to get and set axis and
angle values for convenience.
Note that there is one very common mistake that is easy to make when
setting the value of an SbRotation, and that is to inadvertently use
the wrong SbRotation constructor. This example should clarify the
problem:
SbRotation rotation(0, 0, 1, 1.5707963f);
The programmer clearly tries to set a PI/2 rotation around the Z axis,
but this will fail, as the SbRotation constructor invoked above is the
one that takes as arguments the 4 floats of a quaternion. What the
programmer almost certainly wanted to do was to use the SbRotation
constructor that takes a rotation vector and a rotation angle, which is
invoked like this:
SbRotation rotation(SbVec3f(0, 0, 1), 1.5707963f);
Another common problem is to set the rotation value to exactly 0.0,
while wanting to store just the information about a rotation angle:
rotations are internally handled as quaternions, and when converting
from an angle and a rotation value to a quaternion representation, the
information about the angle ’gets lost’ if there is no actual rotation.
See also:
SbMatrix
Constructor & Destructor Documentation
SbRotation::SbRotation (void) The default constructor just initializes a
valid rotation. The actual value is unspecified, and you should not
depend on it.
SbRotation::SbRotation (const SbVec3f & axis, const float radians)
Construct a new SbRotation object initialized with the given axis-of-
rotation and rotation angle.
SbRotation::SbRotation (const float q[4]) Construct a new SbRotation object
initialized with the given quaternion components.
The array must be ordered as follows:
q[0] = x, q[1] = y, q[2] = z and q[3] = w, where the quaternion is
specified by q=w+xi+yj+zk.
SbRotation::SbRotation (const float q0, const float q1, const float q2,
const float q3) Construct a new SbRotation object initialized with the
given quaternion components.
SbRotation::SbRotation (const SbMatrix & m) Construct a new SbRotation
object initialized with the given rotation matrix.
SbRotation::SbRotation (const SbVec3f & rotateFrom, const SbVec3f &
rotateTo) Construct a rotation which is the minimum rotation necessary
to make vector rotateFrom point in the direction of vector rotateTo.
Example:
#include <Inventor/SbRotation.h>
#include <Inventor/SbVec3f.h>
#include <cstdio>
int
main(void)
{
SbVec3f from(10, 0, 0);
SbVec3f to(0, 10, 0);
SbRotation rot(from, to);
SbVec3f axis;
float angle;
rot.getValue(axis, angle);
axis.print(stdout);
printf(’ angle==%f0, angle);
return 0;
}
Member Function Documentation
const float * SbRotation::getValue (void) const Return pointer to an array
with the rotation expressed as four quaternion values.
See also:
setValue().
void SbRotation::getValue (float & q0, float & q1, float & q2, float & q3)
const Return the four quaternion components representing the rotation.
See also:
setValue().
SbRotation & SbRotation::setValue (const float q0, const float q1, const
float q2, const float q3) Set the rotation.
See also:
getValue().
void SbRotation::getValue (SbVec3f & axis, float & radians) const Return
the rotation in the form of an axis-of-rotation and a rotation angle.
See also:
setValue().
void SbRotation::getValue (SbMatrix & matrix) const Return this rotation in
the form of a matrix.
See also:
setValue().
SbRotation & SbRotation::invert (void) Invert the rotation. Returns
reference to self.
See also:
inverse()
SbRotation SbRotation::inverse (void) const Non-destructively inverses the
rotation and returns the result.
See also:
invert()
SbRotation & SbRotation::setValue (const float q[4]) Reset the rotation by
the four quaternions in the array.
See also:
getValue().
SbRotation & SbRotation::setValue (const SbMatrix & m) Set the rotation
from the components of the given matrix. Returns reference to self.
See also:
getValue().
SbRotation & SbRotation::setValue (const SbVec3f & axis, const float
radians) Reset rotation with the given axis-of-rotation and rotation
angle. Returns reference to self.
Make sure axis is not the null vector when calling this method.
See also:
getValue().
SbRotation & SbRotation::setValue (const SbVec3f & rotateFrom, const
SbVec3f & rotateTo) Construct a rotation which is the minimum rotation
necessary to make vector rotateFrom point in the direction of vector
rotateTo.
Returns reference to self.
See SbRotation constructor with corresponding input arguments for a
simple code example.
See also:
getValue().
SbRotation & SbRotation::operator*= (const SbRotation & q) Multiplies the
quaternions.
Note that order is important when combining quaternions with the
multiplication operator.
SbRotation & SbRotation::operator*= (const float s) Multiplies components
of quaternion with scalar value s. Returns reference to self.
SbBool SbRotation::equals (const SbRotation & r, const float tolerance)
const Check the internal quaternion representation vectors for equality
within the given tolerance.
void SbRotation::multVec (const SbVec3f & src, SbVec3f & dst) const Rotate
the src vector and put the result in dst.
It is safe to let src and dst be the same SbVec3f instance.
void SbRotation::scaleAngle (const float scaleFactor) Scale the angle of
rotation by scaleFactor.
SbRotation slerp (const SbRotation & rot0, const SbRotation & rot1, float
t) [static] Interpolates along the shortest path between the two
rotation positions (from rot0 to rot1).
Returns the SbRotation which will rotate rot0 the given part t of the
spherical distance towards rot1, where t=0 will yield rot0 and t=1 will
yield rot1.
t should be in the interval [0, 1].
SbRotation SbRotation::identity (void) [static] Returns an identity
rotation.
void SbRotation::print (FILE * fp) const Dump the state of this object to
the fp file stream. Only works in debug version of library, method does
nothing in an optimized compile.
Friends And Related Function Documentation
int operator== (const SbRotation & q1, const SbRotation & q2) [friend]
Check if the two rotations are equal.
See also:
equals().
int operator!= (const SbRotation & q1, const SbRotation & q2) [friend]
Check if the two rotations are unequal.
See also:
equals().
SbRotation operator* (const SbRotation & q1, const SbRotation & q2)
[friend] Multiplies the two rotations and returns the result.
Note that order is important when combining quaternions with the
multiplication operator.
Author
Generated automatically by Doxygen for Coin from the source code.