# QVector2D Class

The QVector2D class represents a vector or vertex in 2D space. More...

Header: | #include <QVector2D> |

qmake: | QT += gui |

Since: | Qt 4.6 |

This class was introduced in Qt 4.6.

## Public Functions

QVector2D(const QVector4D &vector) | |

QVector2D(const QVector3D &vector) | |

QVector2D(const QPointF &point) | |

QVector2D(const QPoint &point) | |

QVector2D(float xpos, float ypos) | |

QVector2D() | |

float | distanceToLine(const QVector2D &point, const QVector2D &direction) const |

float | distanceToPoint(const QVector2D &point) const |

bool | isNull() const |

float | length() const |

float | lengthSquared() const |

void | normalize() |

QVector2D | normalized() const |

void | setX(float x) |

void | setY(float y) |

QPoint | toPoint() const |

QPointF | toPointF() const |

QVector3D | toVector3D() const |

QVector4D | toVector4D() const |

float | x() const |

float | y() const |

QVariant | operator QVariant() const |

QVector2D & | operator*=(float factor) |

QVector2D & | operator*=(const QVector2D &vector) |

QVector2D & | operator+=(const QVector2D &vector) |

QVector2D & | operator-=(const QVector2D &vector) |

QVector2D & | operator/=(float divisor) |

QVector2D & | operator/=(const QVector2D &vector) |

float & | operator[](int i) |

float | operator[](int i) const |

## Static Public Members

float | dotProduct(const QVector2D &v1, const QVector2D &v2) |

## Related Non-Members

bool | qFuzzyCompare(const QVector2D &v1, const QVector2D &v2) |

bool | operator!=(const QVector2D &v1, const QVector2D &v2) |

const QVector2D | operator*(float factor, const QVector2D &vector) |

const QVector2D | operator*(const QVector2D &vector, float factor) |

const QVector2D | operator*(const QVector2D &v1, const QVector2D &v2) |

const QVector2D | operator+(const QVector2D &v1, const QVector2D &v2) |

const QVector2D | operator-(const QVector2D &v1, const QVector2D &v2) |

const QVector2D | operator-(const QVector2D &vector) |

const QVector2D | operator/(const QVector2D &vector, float divisor) |

const QVector2D | operator/(const QVector2D &vector, const QVector2D &divisor) |

QDataStream & | operator<<(QDataStream &stream, const QVector2D &vector) |

bool | operator==(const QVector2D &v1, const QVector2D &v2) |

QDataStream & | operator>>(QDataStream &stream, QVector2D &vector) |

## Detailed Description

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

**See also **QVector3D, QVector4D, and QQuaternion.

## Member Function Documentation

### QVector2D::QVector2D(const QVector4D &*vector*)

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

**See also **toVector4D().

### QVector2D::QVector2D(const QVector3D &*vector*)

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

**See also **toVector3D().

### QVector2D::QVector2D(const QPointF &*point*)

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

### QVector2D::QVector2D(const QPoint &*point*)

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

### QVector2D::QVector2D(float *xpos*, float *ypos*)

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

### QVector2D::QVector2D()

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

### float QVector2D::distanceToLine(const QVector2D &*point*, const QVector2D &*direction*) const

Returns the distance that this vertex is from a line defined by *point* and the unit vector *direction*.

If *direction* is a null vector, then it does not define a line. In that case, the distance from *point* to this vertex is returned.

This function was introduced in Qt 5.1.

**See also **distanceToPoint().

### float QVector2D::distanceToPoint(const QVector2D &*point*) const

Returns the distance from this vertex to a point defined by the vertex *point*.

This function was introduced in Qt 5.1.

**See also **distanceToLine().

`[static] `

float QVector2D::dotProduct(const QVector2D &*v1*, const QVector2D &*v2*)

Returns the dot product of *v1* and *v2*.

### bool QVector2D::isNull() const

Returns `true`

if the x and y coordinates are set to 0.0, otherwise returns `false`

.

### float QVector2D::length() const

Returns the length of the vector from the origin.

**See also **lengthSquared() and normalized().

### float QVector2D::lengthSquared() const

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

**See also **length() and dotProduct().

### void QVector2D::normalize()

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.

**See also **length() and normalized().

### QVector2D QVector2D::normalized() const

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.

**See also **length() and normalize().

### void QVector2D::setX(float *x*)

Sets the x coordinate of this point to the given *x* coordinate.

### void QVector2D::setY(float *y*)

Sets the y coordinate of this point to the given *y* coordinate.

### QPoint QVector2D::toPoint() const

Returns the QPoint form of this 2D vector.

**See also **toPointF() and toVector3D().

### QPointF QVector2D::toPointF() const

Returns the QPointF form of this 2D vector.

**See also **toPoint() and toVector3D().

### QVector3D QVector2D::toVector3D() const

Returns the 3D form of this 2D vector, with the z coordinate set to zero.

**See also **toVector4D() and toPoint().

### QVector4D QVector2D::toVector4D() const

Returns the 4D form of this 2D vector, with the z and w coordinates set to zero.

**See also **toVector3D() and toPoint().

### float QVector2D::x() const

Returns the x coordinate of this point.

### float QVector2D::y() const

Returns the y coordinate of this point.

### QVariant QVector2D::operator QVariant() const

Returns the 2D vector as a QVariant.

### QVector2D &QVector2D::operator*=(float *factor*)

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

**See also **operator/=().

### QVector2D &QVector2D::operator*=(const QVector2D &*vector*)

Multiplies the components of this vector by the corresponding components in *vector*.

### QVector2D &QVector2D::operator+=(const QVector2D &*vector*)

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

**See also **operator-=().

### QVector2D &QVector2D::operator-=(const QVector2D &*vector*)

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

**See also **operator+=().

### QVector2D &QVector2D::operator/=(float *divisor*)

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

**See also **operator*=().

### QVector2D &QVector2D::operator/=(const QVector2D &*vector*)

Divides the components of this vector by the corresponding components in *vector*.

This function was introduced in Qt 5.5.

**See also **operator*=().

### float &QVector2D::operator[](int *i*)

Returns the component of the vector at index position *i* as a modifiable reference.

*i* must be a valid index position in the vector (i.e., 0 <= *i* < 2).

This function was introduced in Qt 5.2.

### float QVector2D::operator[](int *i*) const

Returns the component of the vector at index position *i*.

*i* must be a valid index position in the vector (i.e., 0 <= *i* < 2).

This function was introduced in Qt 5.2.

## Related Non-Members

### bool qFuzzyCompare(const QVector2D &*v1*, const QVector2D &*v2*)

Returns `true`

if *v1* and *v2* are equal, allowing for a small fuzziness factor for floating-point comparisons; false otherwise.

### bool operator!=(const QVector2D &*v1*, const QVector2D &*v2*)

Returns `true`

if *v1* is not equal to *v2*; otherwise returns `false`

. This operator uses an exact floating-point comparison.

### const QVector2D operator*(float *factor*, const QVector2D &*vector*)

Returns a copy of the given *vector*, multiplied by the given *factor*.

**See also **QVector2D::operator*=().

### const QVector2D operator*(const QVector2D &*vector*, float *factor*)

Returns a copy of the given *vector*, multiplied by the given *factor*.

**See also **QVector2D::operator*=().

### const QVector2D operator*(const QVector2D &*v1*, const QVector2D &*v2*)

Multiplies the components of *v1* by the corresponding components in *v2*.

### const QVector2D operator+(const QVector2D &*v1*, const QVector2D &*v2*)

Returns a QVector2D object that is the sum of the given vectors, *v1* and *v2*; each component is added separately.

**See also **QVector2D::operator+=().

### const QVector2D operator-(const QVector2D &*v1*, const QVector2D &*v2*)

Returns a QVector2D object that is formed by subtracting *v2* from *v1*; each component is subtracted separately.

**See also **QVector2D::operator-=().

### const QVector2D operator-(const QVector2D &*vector*)

This is an overloaded function.

Returns a QVector2D object that is formed by changing the sign of the components of the given *vector*.

Equivalent to `QVector2D(0,0) - vector`

.

### const QVector2D operator/(const QVector2D &*vector*, float *divisor*)

Returns the QVector2D object formed by dividing all three components of the given *vector* by the given *divisor*.

**See also **QVector2D::operator/=().

### const QVector2D operator/(const QVector2D &*vector*, const QVector2D &*divisor*)

Returns the QVector2D object formed by dividing components of the given *vector* by a respective components of the given *divisor*.

This function was introduced in Qt 5.5.

**See also **QVector2D::operator/=().

### QDataStream &operator<<(QDataStream &*stream*, const QVector2D &*vector*)

Writes the given *vector* to the given *stream* and returns a reference to the stream.

**See also **Serializing Qt Data Types.

### bool operator==(const QVector2D &*v1*, const QVector2D &*v2*)

Returns `true`

if *v1* is equal to *v2*; otherwise returns `false`

. This operator uses an exact floating-point comparison.

### QDataStream &operator>>(QDataStream &*stream*, QVector2D &*vector*)

Reads a 2D vector from the given *stream* into the given *vector* and returns a reference to the stream.

**See also **Serializing Qt Data Types.

© 2021 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.