# QVector4D Class

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

Header: | #include <QVector4D> |

CMake: | find_package(Qt6 COMPONENTS Gui REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Gui) |

qmake: | QT += gui |

## Public Functions

QVector4D(QVector3D vector, float wpos) | |

QVector4D(QVector3D vector) | |

QVector4D(QVector2D vector, float zpos, float wpos) | |

QVector4D(QVector2D vector) | |

QVector4D(QPointF point) | |

QVector4D(QPoint point) | |

QVector4D(float xpos, float ypos, float zpos, float wpos) | |

QVector4D() | |

bool | isNull() const |

float | length() const |

float | lengthSquared() const |

void | normalize() |

QVector4D | normalized() const |

void | setW(float w) |

void | setX(float x) |

void | setY(float y) |

void | setZ(float z) |

QPoint | toPoint() const |

QPointF | toPointF() const |

QVector2D | toVector2D() const |

QVector2D | toVector2DAffine() const |

QVector3D | toVector3D() const |

QVector3D | toVector3DAffine() const |

float | w() const |

float | x() const |

float | y() const |

float | z() const |

QVariant | operator QVariant() const |

QVector4D & | operator*=(float factor) |

QVector4D & | operator*=(QVector4D vector) |

QVector4D & | operator+=(QVector4D vector) |

QVector4D & | operator-=(QVector4D vector) |

QVector4D & | operator/=(float divisor) |

QVector4D & | operator/=(QVector4D vector) |

float & | operator[](int i) |

float | operator[](int i) const |

## Static Public Members

float | dotProduct(QVector4D v1, QVector4D v2) |

## Related Non-Members

bool | qFuzzyCompare(QVector4D v1, QVector4D v2) |

bool | operator!=(QVector4D v1, QVector4D v2) |

QVector4D | operator*(float factor, QVector4D vector) |

QVector4D | operator*(QVector4D vector, float factor) |

QVector4D | operator*(QVector4D v1, QVector4D v2) |

QVector4D | operator+(QVector4D v1, QVector4D v2) |

QVector4D | operator-(QVector4D v1, QVector4D v2) |

QVector4D | operator-(QVector4D vector) |

QVector4D | operator/(QVector4D vector, float divisor) |

QVector4D | operator/(QVector4D vector, QVector4D divisor) |

QDataStream & | operator<<(QDataStream &stream, QVector4D vector) |

bool | operator==(QVector4D v1, QVector4D v2) |

QDataStream & | operator>>(QDataStream &stream, QVector4D &vector) |

## Detailed Description

Vectors are one of the main building blocks of 4D affine representations of 3D space. They consist of four finite floating-point coordinates, traditionally called x, y, z and w.

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

**See also **QQuaternion, QVector2D, and QVector3D.

## Member Function Documentation

### QVector4D::QVector4D(QVector3D *vector*, float *wpos*)

Constructs a 4D vector from the specified 3D *vector*. The w coordinate is set to *wpos*, which must be finite.

**See also **toVector3D().

### QVector4D::QVector4D(QVector3D *vector*)

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

**See also **toVector3D().

### QVector4D::QVector4D(QVector2D *vector*, float *zpos*, float *wpos*)

Constructs a 4D vector from the specified 2D *vector*. The z and w coordinates are set to *zpos* and *wpos* respectively, each of which must be finite.

**See also **toVector2D().

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

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

**See also **toVector2D().

### QVector4D::QVector4D(QPointF *point*)

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

### QVector4D::QVector4D(QPoint *point*)

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

### QVector4D::QVector4D(float *xpos*, float *ypos*, float *zpos*, float *wpos*)

Constructs a vector with coordinates (*xpos*, *ypos*, *zpos*, *wpos*). All parameters must be finite.

### QVector4D::QVector4D()

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

`[static] `

float QVector4D::dotProduct(QVector4D *v1*, 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`

.

### float QVector4D::length() const

Returns the length of the vector from the origin.

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

### float 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.

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

### 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.

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

### 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.

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

### void QVector4D::setW(float *w*)

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

**See also **w(), setX(), setY(), and setZ().

### void QVector4D::setX(float *x*)

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

**See also **x(), setY(), setZ(), and setW().

### void QVector4D::setY(float *y*)

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

**See also **y(), setX(), setZ(), and setW().

### void QVector4D::setZ(float *z*)

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

**See also **z(), setX(), setY(), and setW().

### QPoint QVector4D::toPoint() const

Returns the QPoint form of this 4D vector. The z and w coordinates are dropped. The x and y coordinates are rounded to nearest integers.

**See also **toPointF() and toVector2D().

### QPointF QVector4D::toPointF() const

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

**See also **toPoint() and toVector2D().

### QVector2D QVector4D::toVector2D() const

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

**See also **toVector2DAffine(), toVector3D(), and toPoint().

### 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.

**See also **toVector2D(), toVector3DAffine(), and toPoint().

### QVector3D QVector4D::toVector3D() const

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

**See also **toVector3DAffine(), toVector2D(), and toPoint().

### 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.

**See also **toVector3D(), toVector2DAffine(), and toPoint().

### float QVector4D::w() const

Returns the w coordinate of this point.

**See also **setW(), x(), y(), and z().

### float QVector4D::x() const

Returns the x coordinate of this point.

**See also **setX(), y(), z(), and w().

### float QVector4D::y() const

Returns the y coordinate of this point.

**See also **setY(), x(), z(), and w().

### float QVector4D::z() const

Returns the z coordinate of this point.

**See also **setZ(), x(), y(), and w().

### QVariant QVector4D::operator QVariant() const

Returns the 4D vector as a QVariant.

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

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

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

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

Multiplies each component of this vector by the corresponding component of *vector* and returns a reference to this vector.

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

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

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

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

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

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

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

### QVector4D &QVector4D::operator/=(float *divisor*)

Divides this vector's coordinates by the given *divisor*, and returns a reference to this vector. The *divisor* must not be either zero or NaN.

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

`[since 5.5] `

QVector4D &QVector4D::operator/=(QVector4D *vector*)

Divides each component of this vector by the corresponding component of *vector* and returns a reference to this vector.

The *vector* must have no component that is either zero or NaN.

This function was introduced in Qt 5.5.

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

`[since 5.2] `

float &QVector4D::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* < 4).

This function was introduced in Qt 5.2.

`[since 5.2] `

float QVector4D::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* < 4).

This function was introduced in Qt 5.2.

## Related Non-Members

### bool qFuzzyCompare(QVector4D *v1*, QVector4D *v2*)

Returns `true`

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

### bool operator!=(QVector4D *v1*, QVector4D *v2*)

Returns `true`

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

. This operator uses an exact floating-point comparison.

### QVector4D operator*(float *factor*, QVector4D *vector*)

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

**See also **QVector4D::operator*=().

### QVector4D operator*(QVector4D *vector*, float *factor*)

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

**See also **QVector4D::operator*=().

### QVector4D operator*(QVector4D *v1*, QVector4D *v2*)

Returns the QVector4D object formed by multiplying each component of *v1* by the corresponding component of *v2*.

**Note: **This is not a cross product of *v1* and *v2* in any sense. (Its components add up to the dot product of *v1* and *v2*.)

**See also **QVector4D::operator*=().

### QVector4D operator+(QVector4D *v1*, QVector4D *v2*)

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

**See also **QVector4D::operator+=().

### QVector4D operator-(QVector4D *v1*, QVector4D *v2*)

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

**See also **QVector4D::operator-=().

### QVector4D operator-(QVector4D *vector*)

This is an overloaded function.

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`

.

### QVector4D operator/(QVector4D *vector*, float *divisor*)

Returns the QVector4D object formed by dividing each component of the given *vector* by the given *divisor*.

The *divisor* must not be either zero or NaN.

**See also **QVector4D::operator/=().

`[since 5.5] `

QVector4D operator/(QVector4D *vector*, QVector4D *divisor*)

Returns the QVector4D object formed by dividing each component of the given *vector* by the corresponding component of the given *divisor*.

The *divisor* must have no component that is either zero or NaN.

This function was introduced in Qt 5.5.

**See also **QVector4D::operator/=().

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

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

**See also **Serializing Qt Data Types.

### bool operator==(QVector4D *v1*, QVector4D *v2*)

Returns `true`

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

. This operator uses an exact floating-point comparison.

### QDataStream &operator>>(QDataStream &*stream*, QVector4D &*vector*)

Reads a 4D vector from the given *stream* into the given *vector* and returns a reference to the stream.

**See also **Serializing Qt Data Types.

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