source: trunk/src/gui/math3d/qvector2d.cpp@ 605

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#include "qvector2d.h"
#include "qvector3d.h"
#include "qvector4d.h"
#include <QtCore/qdebug.h>
#include <QtCore/qvariant.h>
#include <QtCore/qmath.h>

QT_BEGIN_NAMESPACE

#ifndef QT_NO_VECTOR2D

/*!
    \class QVector2D
    \brief The QVector2D class represents a vector or vertex in 2D space.
    \since 4.6
    \ingroup painting
    \ingroup painting-3D

    The QVector2D class can also be used to represent vertices in 2D space.
    We therefore do not need to provide a separate vertex class.

    \sa QVector3D, QVector4D, QQuaternion
*/

/*!
    \fn QVector2D::QVector2D()

    Constructs a null vector, i.e. with coordinates (0, 0, 0).
*/

/*!
    \fn QVector2D::QVector2D(qreal xpos, qreal ypos)

    Constructs a vector with coordinates (\a xpos, \a ypos).
*/

/*!
    \fn QVector2D::QVector2D(const QPoint& point)

    Constructs a vector with x and y coordinates from a 2D \a point.
*/

/*!
    \fn QVector2D::QVector2D(const QPointF& point)

    Constructs a vector with x and y coordinates from a 2D \a point.
*/

#ifndef QT_NO_VECTOR3D

/*!
    Constructs a vector with x and y coordinates from a 3D \a vector.
    The z coordinate of \a vector is dropped.

    \sa toVector3D()
*/
QVector2D::QVector2D(const QVector3D& vector)
{
    xp = vector.xp;
    yp = vector.yp;
}

#endif

#ifndef QT_NO_VECTOR4D

/*!
    Constructs a vector with x and y coordinates from a 3D \a vector.
    The z and w coordinates of \a vector are dropped.

    \sa toVector4D()
*/
QVector2D::QVector2D(const QVector4D& vector)
{
    xp = vector.xp;
    yp = vector.yp;
}

#endif

/*!
    \fn bool QVector2D::isNull() const

    Returns true if the x and y coordinates are set to 0.0,
    otherwise returns false.
*/

/*!
    \fn qreal QVector2D::x() const

    Returns the x coordinate of this point.

    \sa setX(), y()
*/

/*!
    \fn qreal QVector2D::y() const

    Returns the y coordinate of this point.

    \sa setY(), x()
*/

/*!
    \fn void QVector2D::setX(qreal x)

    Sets the x coordinate of this point to the given \a x coordinate.

    \sa x(), setY()
*/

/*!
    \fn void QVector2D::setY(qreal y)

    Sets the y coordinate of this point to the given \a y coordinate.

    \sa y(), setX()
*/

/*!
    Returns the length of the vector from the origin.

    \sa lengthSquared(), normalized()
*/
qreal QVector2D::length() const
{
    return qSqrt(xp * xp + yp * yp);
}

/*!
    Returns the squared length of the vector from the origin.
    This is equivalent to the dot product of the vector with itself.

    \sa length(), dotProduct()
*/
qreal QVector2D::lengthSquared() const
{
    return xp * xp + yp * yp;
}

/*!
    Returns the normalized unit vector form of this vector.

    If this vector is null, then a null vector is returned.  If the length
    of the vector is very close to 1, then the vector will be returned as-is.
    Otherwise the normalized form of the vector of length 1 will be returned.

    \sa length(), normalize()
*/
QVector2D QVector2D::normalized() const
{
    // Need some extra precision if the length is very small.
    double len = double(xp) * double(xp) +
                 double(yp) * double(yp);
    if (qFuzzyIsNull(len - 1.0f))
        return *this;
    else if (!qFuzzyIsNull(len))
        return *this / qSqrt(len);
    else
        return QVector2D();
}

/*!
    Normalizes the currect vector in place.  Nothing happens if this
    vector is a null vector or the length of the vector is very close to 1.

    \sa length(), normalized()
*/
void QVector2D::normalize()
{
    // Need some extra precision if the length is very small.
    double len = double(xp) * double(xp) +
                 double(yp) * double(yp);
    if (qFuzzyIsNull(len - 1.0f) || qFuzzyIsNull(len))
        return;

    len = qSqrt(len);

    xp /= len;
    yp /= len;
}

/*!
    \fn QVector2D &QVector2D::operator+=(const QVector2D &vector)

    Adds the given \a vector to this vector and returns a reference to
    this vector.

    \sa operator-=()
*/

/*!
    \fn QVector2D &QVector2D::operator-=(const QVector2D &vector)

    Subtracts the given \a vector from this vector and returns a reference to
    this vector.

    \sa operator+=()
*/

/*!
    \fn QVector2D &QVector2D::operator*=(qreal factor)

    Multiplies this vector's coordinates by the given \a factor, and
    returns a reference to this vector.

    \sa operator/=()
*/

/*!
    \fn QVector2D &QVector2D::operator*=(const QVector2D &vector)

    Multiplies the components of this vector by the corresponding
    components in \a vector.
*/

/*!
    \fn QVector2D &QVector2D::operator/=(qreal divisor)

    Divides this vector's coordinates by the given \a divisor, and
    returns a reference to this vector.

    \sa operator*=()
*/

/*!