- Qt 6.9
- Qt GUI
- C++ Classes
- QVector4D
- Qt 6.9.2 Reference Documentation

# QVector4D Class

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

Header: | `#include <QVector4D>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Gui)` `target_link_libraries(mytarget PRIVATE Qt6::Gui)`
qmake: | `QT += gui`

- List of all members, including inherited members
- QVector4D is part of Rendering in 3D.

## Public Functions

| QVector4D()
| QVector4D(QPoint point)
| QVector4D(QPointF point)
| QVector4D(QVector2D vector)
| QVector4D(QVector3D vector)
| QVector4D(QVector3D vector, float wpos)
| QVector4D(QVector2D vector, float zpos, float wpos)
| QVector4D(float xpos, float ypos, float zpos, float wpos)
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*=(QVector4D vector)
QVector4D & | operator*=(float factor)
QVector4D & | operator+=(QVector4D vector)
QVector4D & | operator-=(QVector4D vector)
QVector4D & | operator/=(QVector4D vector)
QVector4D & | operator/=(float divisor)
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*(QVector4D v1, QVector4D v2)
QVector4D | operator*(QVector4D vector, float factor)
QVector4D | operator*(float factor, QVector4D vector)
QVector4D | operator+(QVector4D v1, QVector4D v2)
QVector4D | operator-(QVector4D v1, QVector4D v2)
QVector4D | operator-(QVector4D vector)
QVector4D | operator/(QVector4D vector, QVector4D divisor)
QVector4D | operator/(QVector4D vector, float 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

### `[constexpr noexcept]` QVector4D::QVector4D()

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

### `[explicit constexpr noexcept]` QVector4D::QVector4D(QPoint point)

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

### `[explicit constexpr noexcept]` QVector4D::QVector4D(QPointF point)

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

### `[explicit constexpr noexcept]` 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().

### `[explicit constexpr noexcept]` QVector4D::QVector4D(QVector3D vector)

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

See also toVector3D().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` QVector4D::QVector4D(float xpos, float ypos, float zpos, float wpos)

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

### `[static constexpr noexcept]` float QVector4D::dotProduct(QVector4D v1, QVector4D v2)

Returns the dot product of v1 and v2.

### `[constexpr noexcept]` bool QVector4D::isNull() const

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

### `[noexcept]` float QVector4D::length() const

Returns the length of the vector from the origin.

See also lengthSquared() and normalized().

### `[constexpr noexcept]` 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().

### `[noexcept]` void QVector4D::normalize()

Normalizes the current 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().

### `[noexcept]` 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().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` QPointF QVector4D::toPointF() const

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

See also toPoint() and toVector2D().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` QVector3D QVector4D::toVector3D() const

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

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

### `[constexpr noexcept]` 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().

### `[constexpr noexcept]` float QVector4D::w() const

Returns the w coordinate of this point.

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

### `[constexpr noexcept]` float QVector4D::x() const

Returns the x coordinate of this point.

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

### `[constexpr noexcept]` float QVector4D::y() const

Returns the y coordinate of this point.

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

### `[constexpr noexcept]` 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.

### `[constexpr noexcept]` 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*().

### `[constexpr noexcept]` 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*().

### `[constexpr noexcept]` QVector4D &QVector4D::operator+=(QVector4D vector)

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

See also operator-=().

### `[constexpr noexcept]` QVector4D &QVector4D::operator-=(QVector4D vector)

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

See also operator+=().

### `[constexpr]` 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.

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

### `[constexpr]` 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*=().

### `[constexpr]` 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).

### `[constexpr]` 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).

## Related Non-Members

### `[noexcept]` 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.

### `[constexpr noexcept]` 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.

### `[constexpr noexcept]` 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*=().

### `[constexpr noexcept]` QVector4D operator*(QVector4D vector, float factor)

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

See also QVector4D::operator*=().

### `[constexpr noexcept]` QVector4D operator*(float factor, QVector4D vector)

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

See also QVector4D::operator*=().

### `[constexpr noexcept]` 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+=().

### `[constexpr noexcept]` 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-=().

### `[constexpr noexcept]` QVector4D operator-(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`.

This is an overloaded function.

### `[constexpr]` 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.

See also QVector4D::operator/=().

### `[constexpr]` 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/=().

### 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.

### `[constexpr noexcept]` 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.