# QVector4D Class

The QVector4D class represents a vector or vertex in 4D space. More...

## Public Functions

 QVector4D() QVector4D(qreal xpos, qreal ypos, qreal zpos, qreal wpos) QVector4D(const QPoint & point) QVector4D(const QPointF & point) QVector4D(const QVector2D & vector) QVector4D(const QVector2D & vector, qreal zpos, qreal wpos) QVector4D(const QVector3D & vector) QVector4D(const QVector3D & vector, qreal wpos) bool isNull() const qreal length() const qreal lengthSquared() const void normalize() QVector4D normalized() const void setW(qreal w) void setX(qreal x) void setY(qreal y) void setZ(qreal z) QPoint toPoint() const QPointF toPointF() const QVector2D toVector2D() const QVector2D toVector2DAffine() const QVector3D toVector3D() const QVector3D toVector3DAffine() const qreal w() const qreal x() const qreal y() const qreal z() const operator QVariant() const QVector4D & operator*=(qreal factor) QVector4D & operator*=(const QVector4D & vector) QVector4D & operator+=(const QVector4D & vector) QVector4D & operator-=(const QVector4D & vector) QVector4D & operator/=(qreal divisor)

## Static Public Members

 qreal dotProduct(const QVector4D & v1, const QVector4D & v2)
 bool qFuzzyCompare(const QVector4D & v1, const QVector4D & v2) bool operator!=(const QVector4D & v1, const QVector4D & v2) const QVector4D operator*(qreal factor, const QVector4D & vector) const QVector4D operator*(const QVector4D & vector, qreal factor) const QVector4D operator*(const QVector4D & v1, const QVector4D & v2) const QVector4D operator+(const QVector4D & v1, const QVector4D & v2) const QVector4D operator-(const QVector4D & v1, const QVector4D & v2) const QVector4D operator-(const QVector4D & vector) const QVector4D operator/(const QVector4D & vector, qreal divisor) QDataStream & operator<<(QDataStream & stream, const QVector4D & vector) bool operator==(const QVector4D & v1, const QVector4D & v2) QDataStream & operator>>(QDataStream & stream, QVector4D & vector)

## Detailed Description

The QVector4D class represents a vector or vertex in 4D space.

The QVector4D class can also be used to represent vertices in 4D space. We therefore do not need to provide a separate vertex class.

Note: By design values in the QVector4D instance are stored as `float`. This means that on platforms where the `qreal` arguments to QVector4D functions are represented by `double` values, it is possible to lose precision.

## Member Function Documentation

### QVector4D::QVector4D()

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

### QVector4D::QVector4D(qreal xpos, qreal ypos, qreal zpos, qreal wpos)

Constructs a vector with coordinates (xpos, ypos, zpos, wpos).

### QVector4D::QVector4D(const QPoint & point)

Constructs a vector with x and y coordinates from a 2D point, and z and w coordinates of 0.

### QVector4D::QVector4D(const QPointF & point)

Constructs a vector with x and y coordinates from a 2D point, and z and w coordinates of 0.

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

Constructs a 4D vector from the specified 2D vector. The z and w coordinates are set to zero.

### QVector4D::QVector4D(const QVector2D & vector, qreal zpos, qreal wpos)

Constructs a 4D vector from the specified 2D vector. The z and w coordinates are set to zpos and wpos respectively.

### QVector4D::QVector4D(const QVector3D & vector)

Constructs a 4D vector from the specified 3D vector. The w coordinate is set to zero.

### QVector4D::QVector4D(const QVector3D & vector, qreal wpos)

Constructs a 4D vector from the specified 3D vector. The w coordinate is set to wpos.

### `[static] `qreal QVector4D::dotProduct(const QVector4D & v1, const QVector4D & v2)

Returns the dot product of v1 and v2.

### bool QVector4D::isNull() const

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

### qreal QVector4D::length() const

Returns the length of the vector from the origin.

### qreal QVector4D::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 QVector4D::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.

### QVector4D QVector4D::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 QVector4D::setW(qreal w)

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

### void QVector4D::setX(qreal x)

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

### void QVector4D::setY(qreal y)

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

### void QVector4D::setZ(qreal z)

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

### QPoint QVector4D::toPoint() const

Returns the QPoint form of this 4D vector. The z and w coordinates are dropped.

### QPointF QVector4D::toPointF() const

Returns the QPointF form of this 4D vector. The z and w coordinates are dropped.

### QVector2D QVector4D::toVector2D() const

Returns the 2D vector form of this 4D vector, dropping the z and w coordinates.

### QVector2D QVector4D::toVector2DAffine() const

Returns the 2D vector form of this 4D vector, dividing the x and y coordinates by the w coordinate and dropping the z coordinate. Returns a null vector if w is zero.

### QVector3D QVector4D::toVector3D() const

Returns the 3D vector form of this 4D vector, dropping the w coordinate.

### QVector3D QVector4D::toVector3DAffine() const

Returns the 3D vector form of this 4D vector, dividing the x, y, and z coordinates by the w coordinate. Returns a null vector if w is zero.

### qreal QVector4D::w() const

Returns the w coordinate of this point.

### qreal QVector4D::x() const

Returns the x coordinate of this point.

### qreal QVector4D::y() const

Returns the y coordinate of this point.

### qreal QVector4D::z() const

Returns the z coordinate of this point.

### QVector4D::operator QVariant() const

Returns the 4D vector as a QVariant.

### QVector4D & QVector4D::operator*=(qreal factor)

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

### QVector4D & QVector4D::operator*=(const QVector4D & vector)

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

### QVector4D & QVector4D::operator+=(const QVector4D & vector)

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

### QVector4D & QVector4D::operator-=(const QVector4D & vector)

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

### QVector4D & QVector4D::operator/=(qreal divisor)

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

## Related Non-Members

### boolqFuzzyCompare(const QVector4D & v1, const QVector4D & v2)

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

### booloperator!=(const QVector4D & v1, const QVector4D & v2)

Returns true if v1 is not equal to v2; otherwise returns false. This operator uses an exact floating-point comparison.

### const QVector4Doperator*(qreal factor, const QVector4D & vector)

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

### const QVector4Doperator*(const QVector4D & vector, qreal factor)

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

### const QVector4Doperator*(const QVector4D & v1, const QVector4D & v2)

Returns the vector consisting of the multiplication of the components from v1 and v2.

### const QVector4Doperator+(const QVector4D & v1, const QVector4D & v2)

Returns a QVector4D object that is the sum of the given vectors, v1 and v2; each component is added separately.

### const QVector4Doperator-(const QVector4D & v1, const QVector4D & v2)

Returns a QVector4D object that is formed by subtracting v2 from v1; each component is subtracted separately.

### const QVector4Doperator-(const QVector4D & vector)

Returns a QVector4D object that is formed by changing the sign of all three components of the given vector.

Equivalent to `QVector4D(0,0,0,0) - vector`.

### const QVector4Doperator/(const QVector4D & vector, qreal divisor)

Returns the QVector4D object formed by dividing all four components of the given vector by the given divisor.

### QDataStream & operator<<(QDataStream & stream, const QVector4D & vector)

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