SFML - Simple and Fast Multimedia Library

SFML 3.0.2
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Public Member Functions | List of all members
sf::Transformable Class Reference
Graphics module

Decomposed transform defined by a position, a rotation and a scale. More...

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

Inheritance diagram for sf::Transformable:

## Public Member Functions
| Transformable ()=default
| Default constructor.
virtual | ~Transformable ()=default
| Virtual destructor.
void | setPosition (Vector2f position)
| set the position of the object
void | setRotation (Angle angle)
| set the orientation of the object
void | setScale (Vector2f factors)
| set the scale factors of the object
void | setOrigin (Vector2f origin)
| set the local origin of the object
Vector2f | getPosition () const
| get the position of the object
Angle | getRotation () const
| get the orientation of the object
Vector2f | getScale () const
| get the current scale of the object
Vector2f | getOrigin () const
| get the local origin of the object
void | move (Vector2f offset)
| Move the object by a given offset.
void | rotate (Angle angle)
| Rotate the object.
void | scale (Vector2f factor)
| Scale the object.
const Transform & | getTransform () const
| get the combined transform of the object
const Transform & | getInverseTransform () const
| get the inverse of the combined transform of the object

## Detailed Description

Decomposed transform defined by a position, a rotation and a scale.

This class is provided for convenience, on top of sf::Transform.

sf::Transform, as a low-level class, offers a great level of flexibility but it is not always convenient to manage. Indeed, one can easily combine any kind of operation, such as a translation followed by a rotation followed by a scaling, but once the result transform is built, there's no way to go backward and, let's say, change only the rotation without modifying the translation and scaling. The entire transform must be recomputed, which means that you need to retrieve the initial translation and scale factors as well, and combine them the same way you did before updating the rotation. This is a tedious operation, and it requires to store all the individual components of the final transform.

That's exactly what sf::Transformable was written for: it hides these variables and the composed transform behind an easy to use interface. You can set or get any of the individual components without worrying about the others. It also provides the composed transform (as a sf::Transform), and keeps it up-to-date.

In addition to the position, rotation and scale, sf::Transformable provides an "origin" component, which represents the local origin of the three other components. Let's take an example with a 10x10 pixels sprite. By default, the sprite is positioned/rotated/scaled relative to its top-left corner, because it is the local point (0, 0). But if we change the origin to be (5, 5), the sprite will be positioned/rotated/scaled around its center instead. And if we set the origin to (10, 10), it will be transformed around its bottom-right corner.

To keep the sf::Transformable class simple, there's only one origin for all the components. You cannot position the sprite relative to its top-left corner while rotating it around its center, for example. To do such things, use sf::Transform directly.

sf::Transformable can be used as a base class. It is often combined with sf::Drawable – that's what SFML's sprites, texts and shapes do.

class MyEntity : public sf::Transformable, public sf::Drawable
{
void draw(sf::RenderTarget& target, sf::RenderStates states) const override
{
states.transform *= getTransform();
target.draw(..., states);
}
};
MyEntity entity;
entity.setPosition({10, 20});
entity.setRotation(sf::degrees(45));
window.draw(entity);
sf::Drawable
Abstract base class for objects that can be drawn to a render target.
Definition Drawable.hpp:44
sf::Drawable::draw
virtual void draw(RenderTarget &target, RenderStates states) const =0
Draw the object to a render target.
sf::RenderTarget
Base class for all render targets (window, texture, ...)
Definition RenderTarget.hpp:63
sf::RenderTarget::draw
void draw(const Drawable &drawable, const RenderStates &states=RenderStates::Default)
Draw a drawable object to the render target.
sf::Transformable
Decomposed transform defined by a position, a rotation and a scale.
Definition Transformable.hpp:44
sf::Transformable::getTransform
const Transform & getTransform() const
get the combined transform of the object
sf::degrees
constexpr Angle degrees(float angle)
Construct an angle value from a number of degrees.
sf::RenderStates
Define the states used for drawing to a RenderTarget
Definition RenderStates.hpp:48
sf::RenderStates::transform
Transform transform
Transform.
Definition RenderStates.hpp:133

It can also be used as a member, if you don't want to use its API directly (because you don't need all its functions, or you have different naming conventions for example).

class MyEntity
{
public:
void SetPosition(const MyVector& v)
{
myTransform.setPosition(v.x(), v.y());
}
void Draw(sf::RenderTarget& target) const
{
target.draw(..., myTransform.getTransform());
}
private:
sf::Transformable myTransform;
};

A note on coordinates and undistorted rendering:
By default, SFML (or more exactly, OpenGL) may interpolate drawable objects such as sprites or texts when rendering. While this allows transitions like slow movements or rotations to appear smoothly, it can lead to unwanted results in some cases, for example blurred or distorted objects. In order to render a sf::Drawable object pixel-perfectly, make sure the involved coordinates allow a 1:1 mapping of pixels in the window to texels (pixels in the texture). More specifically, this means:

- The object's position, origin and scale have no fractional part
- The object's and the view's rotation are a multiple of 90 degrees
- The view's center and size have no fractional part

See also
  sf::Transform

Definition at line 43 of file Transformable.hpp.

## Constructor & Destructor Documentation

## ◆ Transformable()

sf::Transformable::Transformable | ( |  | ) |
| default

Default constructor.

## ◆ ~Transformable()

virtual sf::Transformable::~Transformable | ( |  | ) |
| virtualdefault

Virtual destructor.

## Member Function Documentation

## ◆ getInverseTransform()

const Transform & sf::Transformable::getInverseTransform | ( |  | ) | const
| nodiscard

get the inverse of the combined transform of the object

Returns
  Inverse of the combined transformations applied to the object

See also
  getTransform

## ◆ getOrigin()

Vector2f sf::Transformable::getOrigin | ( |  | ) | const
| nodiscard

get the local origin of the object

Returns
  Current origin

See also
  setOrigin

## ◆ getPosition()

Vector2f sf::Transformable::getPosition | ( |  | ) | const
| nodiscard

get the position of the object

Returns
  Current position

See also
  setPosition

## ◆ getRotation()

Angle sf::Transformable::getRotation | ( |  | ) | const
| nodiscard

get the orientation of the object

The rotation is always in the range [0, 360].

Returns
  Current rotation

See also
  setRotation

## ◆ getScale()

Vector2f sf::Transformable::getScale | ( |  | ) | const
| nodiscard

get the current scale of the object

Returns
  Current scale factors

See also
  setScale

## ◆ getTransform()

const Transform & sf::Transformable::getTransform | ( |  | ) | const
| nodiscard

get the combined transform of the object

Returns
  Transform combining the position/rotation/scale/origin of the object

See also
  getInverseTransform

## ◆ move()

void sf::Transformable::move | ( | Vector2f | offset | ) |

Move the object by a given offset.

This function adds to the current position of the object, unlike setPosition which overwrites it. Thus, it is equivalent to the following code:

object.setPosition(object.getPosition() + offset);
sf::Transformable::getPosition
Vector2f getPosition() const
get the position of the object

Parameters

  offset | Offset

See also
  setPosition

## ◆ rotate()

void sf::Transformable::rotate | ( | Angle | angle | ) |

Rotate the object.

This function adds to the current rotation of the object, unlike setRotation which overwrites it. Thus, it is equivalent to the following code:

object.setRotation(object.getRotation() + angle);
sf::Transformable::getRotation
Angle getRotation() const
get the orientation of the object

Parameters

  angle | Angle of rotation

## ◆ scale()

void sf::Transformable::scale | ( | Vector2f | factor | ) |

Scale the object.

This function multiplies the current scale of the object, unlike setScale which overwrites it. Thus, it is equivalent to the following code:

sf::Vector2f scale = object.getScale();
object.setScale(scale.x * factor.x, scale.y * factor.y);
sf::Transformable::scale
void scale(Vector2f factor)
Scale the object.
sf::Vector2f
Vector2< float > Vector2f
Definition Vector2.hpp:210

Parameters

  factor | Scale factors

See also
  setScale

## ◆ setOrigin()

void sf::Transformable::setOrigin | ( | Vector2f | origin | ) |

set the local origin of the object

The origin of an object defines the center point for all transformations (position, scale, rotation). The coordinates of this point must be relative to the top-left corner of the object, and ignore all transformations (position, scale, rotation). The default origin of a transformable object is (0, 0).

Parameters

  origin | New origin

See also
  getOrigin

## ◆ setPosition()

void sf::Transformable::setPosition | ( | Vector2f | position | ) |

set the position of the object

This function completely overwrites the previous position. See the move function to apply an offset based on the previous position instead. The default position of a transformable object is (0, 0).

Parameters

  position | New position

See also
  move, getPosition

## ◆ setRotation()

void sf::Transformable::setRotation | ( | Angle | angle | ) |

set the orientation of the object

This function completely overwrites the previous rotation. See the rotate function to add an angle based on the previous rotation instead. The default rotation of a transformable object is 0.

Parameters

  angle | New rotation

See also
  rotate, getRotation

## ◆ setScale()

void sf::Transformable::setScale | ( | Vector2f | factors | ) |

set the scale factors of the object

This function completely overwrites the previous scale. See the scale function to add a factor based on the previous scale instead. The default scale of a transformable object is (1, 1).

Parameters

  factors | New scale factors

See also
  scale, getScale

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

- Transformable.hpp