sf::Transformable Class Reference

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 constructor.
virtual	~Transformable ()
	Virtual destructor.
void	setPosition (float x, float y)
	set the position of the object
void	setPosition (const Vector2f &position)
	set the position of the object
void	setRotation (float angle)
	set the orientation of the object
void	setScale (float factorX, float factorY)
	set the scale factors of the object
void	setScale (const Vector2f &factors)
	set the scale factors of the object
void	setOrigin (float x, float y)
	set the local origin of the object
void	setOrigin (const Vector2f &origin)
	set the local origin of the object
const Vector2f &	getPosition () const
	get the position of the object
float	getRotation () const
	get the orientation of the object
const Vector2f &	getScale () const
	get the current scale of the object
const Vector2f &	getOrigin () const
	get the local origin of the object
void	move (float offsetX, float offsetY)
	Move the object by a given offset.
void	move (const Vector2f &offset)
	Move the object by a given offset.
void	rotate (float angle)
	Rotate the object.
void	scale (float factorX, float factorY)
	Scale the object.
void	scale (const 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 relatively 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 relatively 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
{
    virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const
    {
        states.transform *= getTransform();
        target.draw(..., states);
    }
};
 
MyEntity entity;
entity.setPosition(10, 20);
entity.setRotation(45);
window.draw(entity);

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 41 of file Transformable.hpp.

Constructor & Destructor Documentation

Transformable()

sf::Transformable::Transformable

(

)

Default constructor.

~Transformable()

virtual sf::Transformable::~Transformable ( )

virtual

Virtual destructor.

Member Function Documentation

getInverseTransform()

const Transform & sf::Transformable::getInverseTransform

(

)

const

get the inverse of the combined transform of the object

Returns

Inverse of the combined transformations applied to the object

See also

getTransform

getOrigin()

const Vector2f & sf::Transformable::getOrigin

(

)

const

get the local origin of the object

Returns

Current origin

See also

setOrigin

getPosition()

const Vector2f & sf::Transformable::getPosition

(

)

const

get the position of the object

Returns

Current position

See also

setPosition

getRotation()

float sf::Transformable::getRotation

(

)

const

get the orientation of the object

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

Returns

Current rotation, in degrees

See also

setRotation

getScale()

const Vector2f & sf::Transformable::getScale

(

)

const

get the current scale of the object

Returns

Current scale factors

See also

setScale

getTransform()

const Transform & sf::Transformable::getTransform

(

)

const

get the combined transform of the object

Returns

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

See also

getInverseTransform

move() [1/2]

void sf::Transformable::move

(

const 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);

Parameters

offset

Offset

See also

setPosition

move() [2/2]

void sf::Transformable::move	(	float	offsetX,
		float	offsetY )

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:

sf::Vector2f pos = object.getPosition();
object.setPosition(pos.x + offsetX, pos.y + offsetY);

Parameters

offsetX	X offset
offsetY	Y offset

See also

setPosition

rotate()

void sf::Transformable::rotate

(

float

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);

Parameters

angle

Angle of rotation, in degrees

scale() [1/2]

void sf::Transformable::scale

(

const 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);

Parameters

factor

Scale factors

See also

setScale

scale() [2/2]

void sf::Transformable::scale	(	float	factorX,
		float	factorY )

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 * factorX, scale.y * factorY);

Parameters

factorX	Horizontal scale factor
factorY	Vertical scale factor

See also

setScale

setOrigin() [1/2]

void sf::Transformable::setOrigin

(

const 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

setOrigin() [2/2]

void sf::Transformable::setOrigin	(	float	x,
		float	y )

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

x	X coordinate of the new origin
y	Y coordinate of the new origin

See also

getOrigin

setPosition() [1/2]

void sf::Transformable::setPosition

(

const 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

setPosition() [2/2]

void sf::Transformable::setPosition	(	float	x,
		float	y )

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

x	X coordinate of the new position
y	Y coordinate of the new position

See also

move, getPosition

setRotation()

void sf::Transformable::setRotation

(

float

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, in degrees

See also

rotate, getRotation

setScale() [1/2]

void sf::Transformable::setScale

(

const 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

setScale() [2/2]

void sf::Transformable::setScale	(	float	factorX,
		float	factorY )

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

factorX	New horizontal scale factor
factorY	New vertical scale factor

See also

scale, getScale

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

• Transformable.hpp