# QVector2D Class

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

## Public Functions

 QVector2D() QVector2D(qreal xpos, qreal ypos) QVector2D(const QPoint & point) QVector2D(const QPointF & point) QVector2D(const QVector3D & vector) QVector2D(const QVector4D & vector) bool isNull() const qreal length() const qreal lengthSquared() const void normalize() QVector2D normalized() const void setX(qreal x) void setY(qreal y) QPoint toPoint() const QPointF toPointF() const QVector3D toVector3D() const QVector4D toVector4D() const qreal x() const qreal y() const operator QVariant() const QVector2D & operator*=(qreal factor) QVector2D & operator*=(const QVector2D & vector) QVector2D & operator+=(const QVector2D & vector) QVector2D & operator-=(const QVector2D & vector) QVector2D & operator/=(qreal divisor)

## Static Public Members

 qreal dotProduct(const QVector2D & v1, const QVector2D & v2)
 bool qFuzzyCompare(const QVector2D & v1, const QVector2D & v2) bool operator!=(const QVector2D & v1, const QVector2D & v2) const QVector2D operator*(qreal factor, const QVector2D & vector) const QVector2D operator*(const QVector2D & vector, qreal 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, qreal 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 represents a vector or vertex in 2D space.

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

Note: By design values in the QVector2D instance are stored as `float`. This means that on platforms where the `qreal` arguments to QVector2D functions are represented by `double` values, it is possible to lose precision.

## Member Function Documentation

### QVector2D::QVector2D()

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

### QVector2D::QVector2D(qreal xpos, qreal ypos)

Constructs a vector with coordinates (xpos, ypos).

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

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

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

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

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

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

### 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.

### `[static] `qreal 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.

### qreal QVector2D::length() const

Returns the length of the vector from the origin.

### qreal 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.

### 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.

### 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.

### void QVector2D::setX(qreal x)

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

### void QVector2D::setY(qreal 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.

### QPointF QVector2D::toPointF() const

Returns the QPointF form of this 2D vector.

### QVector3D QVector2D::toVector3D() const

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

### QVector4D QVector2D::toVector4D() const

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

### qreal QVector2D::x() const

Returns the x coordinate of this point.

### qreal QVector2D::y() const

Returns the y coordinate of this point.

### QVector2D::operator QVariant() const

Returns the 2D vector as a QVariant.

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

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

### 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.

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

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

### QVector2D & QVector2D::operator/=(qreal divisor)

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

## Related Non-Members

### boolqFuzzyCompare(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.

### booloperator!=(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 QVector2Doperator*(qreal factor, const QVector2D & vector)

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

### const QVector2Doperator*(const QVector2D & vector, qreal factor)

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

### const QVector2Doperator*(const QVector2D & v1, const QVector2D & v2)

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

### const QVector2Doperator+(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.

### const QVector2Doperator-(const QVector2D & v1, const QVector2D & v2)

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

### const QVector2Doperator-(const QVector2D & vector)

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 QVector2Doperator/(const QVector2D & vector, qreal divisor)

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

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

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