SFML - Simple and Fast Multimedia Library

SFML 3.1.0
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Public Member Functions | Static Public Attributes | Related Symbols | List of all members
sf::Transform Class Reference
Graphics module

3x3 transform matrix More...

`#include <SFML/Graphics/Transform.hpp>`

## Public Member Functions
constexpr | Transform ()=default
| Default constructor.
constexpr | Transform (float a00, float a01, float a02, float a10, float a11, float a12, float a20, float a21, float a22)
| Construct a transform from a 3x3 matrix.
constexpr const float * | getMatrix () const
| Return the transform as a 4x4 matrix.
constexpr Transform | getInverse () const
| Return the inverse of the transform.
constexpr Vector2f | transformPoint (Vector2f point) const
| Transform a 2D point.
constexpr FloatRect | transformRect (const FloatRect &rectangle) const
| Transform a rectangle.
constexpr Transform & | combine (const Transform &transform)
| Combine the current transform with another one.
constexpr Transform & | translate (Vector2f offset)
| Combine the current transform with a translation.
Transform & | rotate (Angle angle)
| Combine the current transform with a rotation.
Transform & | rotate (Angle angle, Vector2f center)
| Combine the current transform with a rotation.
constexpr Transform & | scale (Vector2f factors)
| Combine the current transform with a scaling.
constexpr Transform & | scale (Vector2f factors, Vector2f center)
| Combine the current transform with a scaling.

## Static Public Attributes
static const Transform | Identity
| The identity transform (does nothing).

## Related Symbols
(Note that these are not member symbols.)
constexpr Transform | operator* (const Transform &left, const Transform &right)
| Overload of binary operator* to combine two transforms.
constexpr Transform & | operator*= (Transform &left, const Transform &right)
| Overload of binary operator*= to combine two transforms.
constexpr Vector2f | operator* (const Transform &left, Vector2f right)
| Overload of binary operator* to transform a point.
constexpr bool | operator== (const Transform &left, const Transform &right)
| Overload of binary operator== to compare two transforms.
constexpr bool | operator!= (const Transform &left, const Transform &right)
| Overload of binary operator!= to compare two transforms.

## Detailed Description

3x3 transform matrix

A sf::Transform specifies how to translate, rotate, scale, shear, project, whatever things.

In mathematical terms, it defines how to transform a coordinate system into another.

For example, if you apply a rotation transform to a sprite, the result will be a rotated sprite. And anything that is transformed by this rotation transform will be rotated the same way, according to its initial position.

Transforms are typically used for drawing. But they can also be used for any computation that requires to transform points between the local and global coordinate systems of an entity (like collision detection).

Example:

// define a translation transform
sf::Transform translation;
translation.translate(20, 50);
// define a rotation transform
sf::Transform rotation;
rotation.rotate(45);
// combine them
sf::Transform transform = translation * rotation;
// use the result to transform stuff...
sf::Vector2f point = transform.transformPoint({10, 20});
sf::FloatRect rect = transform.transformRect(sf::FloatRect({0, 0}, {10, 100}));
sf::Transform
3x3 transform matrix
Definition Transform.hpp:48
sf::Transform::transformPoint
constexpr Vector2f transformPoint(Vector2f point) const
Transform a 2D point.
sf::Transform::rotate
Transform & rotate(Angle angle)
Combine the current transform with a rotation.
sf::Transform::transformRect
constexpr FloatRect transformRect(const FloatRect &rectangle) const
Transform a rectangle.
sf::Transform::translate
constexpr Transform & translate(Vector2f offset)
Combine the current transform with a translation.
sf::FloatRect
Rect< float > FloatRect
Definition Rect.hpp:147
sf::Vector2f
Vector2< float > Vector2f
Definition Vector2.hpp:213

See also
  sf::Transformable, sf::RenderStates

Definition at line 47 of file Transform.hpp.

## Constructor & Destructor Documentation

## ◆ Transform() [1/2]

sf::Transform::Transform | ( |  | ) |
| constexprdefault

Default constructor.

Creates an identity transform (a transform that does nothing).

## ◆ Transform() [2/2]

sf::Transform::Transform | ( | float | a00,
|  | float | a01,
|  | float | a02,
|  | float | a10,
|  | float | a11,
|  | float | a12,
|  | float | a20,
|  | float | a21,
|  | float | a22 )
| constexpr

Construct a transform from a 3x3 matrix.

Parameters

  a00 | Element (0, 0) of the matrix
  a01 | Element (0, 1) of the matrix
  a02 | Element (0, 2) of the matrix
  a10 | Element (1, 0) of the matrix
  a11 | Element (1, 1) of the matrix
  a12 | Element (1, 2) of the matrix
  a20 | Element (2, 0) of the matrix
  a21 | Element (2, 1) of the matrix
  a22 | Element (2, 2) of the matrix

## Member Function Documentation

## ◆ combine()

Transform & sf::Transform::combine | ( | const Transform & | transform | ) |
| constexpr

Combine the current transform with another one.

The result is a transform that is equivalent to applying transform followed by *this. Mathematically, it is equivalent to a matrix multiplication (*this) * transform.

These two statements are equivalent:

left.combine(right);
left *= right;

Parameters

  transform | Transform to combine with this transform

Returns
  Reference to *this

## ◆ getInverse()

Transform sf::Transform::getInverse | ( |  | ) | const
| nodiscardconstexpr

Return the inverse of the transform.

If the inverse cannot be computed, an identity transform is returned.

Returns
  A new transform which is the inverse of self

## ◆ getMatrix()

const float * sf::Transform::getMatrix | ( |  | ) | const
| nodiscardconstexpr

Return the transform as a 4x4 matrix.

This function returns a pointer to an array of 16 floats containing the transform elements as a 4x4 matrix, which is directly compatible with OpenGL functions.

sf::Transform transform = ...;
glLoadMatrixf(transform.getMatrix());
sf::Transform::getMatrix
constexpr const float * getMatrix() const
Return the transform as a 4x4 matrix.

Returns
  Pointer to a 4x4 matrix

## ◆ rotate() [1/2]

Transform & sf::Transform::rotate | ( | Angle | angle | ) |

Combine the current transform with a rotation.

This function returns a reference to *this, so that calls can be chained.

sf::Transform transform;
transform.rotate(sf::degrees(90)).translate(50, 20);
sf::degrees
constexpr Angle degrees(float angle)
Construct an angle value from a number of degrees.

Parameters

  angle | Rotation angle

Returns
  Reference to *this

See also
  translate, scale

## ◆ rotate() [2/2]

Transform & sf::Transform::rotate | ( | Angle | angle,
|  | Vector2f | center )

Combine the current transform with a rotation.

The center of rotation is provided for convenience as a second argument, so that you can build rotations around arbitrary points more easily (and efficiently) than the usual translate(-center).rotate(angle).translate(center).

This function returns a reference to *this, so that calls can be chained.

sf::Transform transform;
transform.rotate(sf::degrees(90), sf::Vector2f(8, 3)).translate(sf::Vector2f(50, 20));

Parameters

  angle | Rotation angle
  center | Center of rotation

Returns
  Reference to *this

See also
  translate, scale

## ◆ scale() [1/2]

Transform & sf::Transform::scale | ( | Vector2f | factors | ) |
| constexpr

Combine the current transform with a scaling.

This function returns a reference to *this, so that calls can be chained.

sf::Transform transform;
transform.scale(sf::Vector2f(2, 1)).rotate(sf::degrees(45));
sf::Transform::scale
constexpr Transform & scale(Vector2f factors)
Combine the current transform with a scaling.

Parameters

  factors | Scaling factors

Returns
  Reference to *this

See also
  translate, rotate

## ◆ scale() [2/2]

Transform & sf::Transform::scale | ( | Vector2f | factors,
|  | Vector2f | center )
| constexpr

Combine the current transform with a scaling.

The center of scaling is provided for convenience as a second argument, so that you can build scaling around arbitrary points more easily (and efficiently) than the usual translate(-center).scale(factors).translate(center).

This function returns a reference to *this, so that calls can be chained.

sf::Transform transform;
transform.scale(sf::Vector2f(2, 1), sf::Vector2f(8, 3)).rotate(45);

Parameters

  factors | Scaling factors
  center | Center of scaling

Returns
  Reference to *this

See also
  translate, rotate

## ◆ transformPoint()

Vector2f sf::Transform::transformPoint | ( | Vector2f | point | ) | const
| nodiscardconstexpr

Transform a 2D point.

These two statements are equivalent:

sf::Vector2f transformedPoint = matrix.transformPoint(point);
sf::Vector2f transformedPoint = matrix * point;

Parameters

  point | Point to transform

Returns
  Transformed point

## ◆ transformRect()

FloatRect sf::Transform::transformRect | ( | const FloatRect & | rectangle | ) | const
| nodiscardconstexpr

Transform a rectangle.

Since SFML doesn't provide support for oriented rectangles, the result of this function is always an axis-aligned rectangle. Which means that if the transform contains a rotation, the bounding rectangle of the transformed rectangle is returned.

Parameters

  rectangle | Rectangle to transform

Returns
  Transformed rectangle

## ◆ translate()

Transform & sf::Transform::translate | ( | Vector2f | offset | ) |
| constexpr

Combine the current transform with a translation.

This function returns a reference to *this, so that calls can be chained.

sf::Transform transform;
transform.translate(sf::Vector2f(100, 200)).rotate(sf::degrees(45));

Parameters

  offset | Translation offset to apply

Returns
  Reference to *this

See also
  rotate, scale

## Friends And Related Symbol Documentation

## ◆ operator!=()

bool operator!= | ( | const Transform & | left,
|  | const Transform & | right )
| related

Overload of binary operator!= to compare two transforms.

This call is equivalent to !(left == right).

Parameters

  left | Left operand (the first transform)
  right | Right operand (the second transform)

Returns
  true if the transforms are not equal, false otherwise

## ◆ operator*() [1/2]

Transform operator* | ( | const Transform & | left,
|  | const Transform & | right )
| related

Overload of binary operator* to combine two transforms.

This call is equivalent to calling Transform(left).combine(right).

Parameters

  left | Left operand (the first transform)
  right | Right operand (the second transform)

Returns
  New combined transform

## ◆ operator*() [2/2]

Vector2f operator* | ( | const Transform & | left,
|  | Vector2f | right )
| related

Overload of binary operator* to transform a point.

This call is equivalent to calling left.transformPoint(right).

Parameters

  left | Left operand (the transform)
  right | Right operand (the point to transform)

Returns
  New transformed point

## ◆ operator*=()

Transform & operator*= | ( | Transform & | left,
|  | const Transform & | right )
| related

Overload of binary operator*= to combine two transforms.

This call is equivalent to calling left.combine(right).

Parameters

  left | Left operand (the first transform)
  right | Right operand (the second transform)

Returns
  The combined transform

## ◆ operator==()

bool operator== | ( | const Transform & | left,
|  | const Transform & | right )
| related

Overload of binary operator== to compare two transforms.

Performs an element-wise comparison of the elements of the left transform with the elements of the right transform.

Parameters

  left | Left operand (the first transform)
  right | Right operand (the second transform)

Returns
  true if the transforms are equal, false otherwise

## Member Data Documentation

## ◆ Identity

const Transform sf::Transform::Identity
| static

The identity transform (does nothing).

Definition at line 265 of file Transform.hpp.

The documentation for this class was generated from the following file:

- Transform.hpp