sf::Transform Class Reference

Define a 3x3 transform matrix. More...

#include <SFML/Graphics/Transform.hpp>

Public Member Functions
	Transform ()
	Default constructor.
	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.
const float *	getMatrix () const
	Return the transform as a 4x4 matrix.
Transform	getInverse () const
	Return the inverse of the transform.
Vector2f	transformPoint (float x, float y) const
	Transform a 2D point.
Vector2f	transformPoint (const Vector2f &point) const
	Transform a 2D point.
FloatRect	transformRect (const FloatRect &rectangle) const
	Transform a rectangle.
Transform &	combine (const Transform &transform)
	Combine the current transform with another one.
Transform &	translate (float x, float y)
	Combine the current transform with a translation.
Transform &	translate (const Vector2f &offset)
	Combine the current transform with a translation.
Transform &	rotate (float angle)
	Combine the current transform with a rotation.
Transform &	rotate (float angle, float centerX, float centerY)
	Combine the current transform with a rotation.
Transform &	rotate (float angle, const Vector2f &center)
	Combine the current transform with a rotation.
Transform &	scale (float scaleX, float scaleY)
	Combine the current transform with a scaling.
Transform &	scale (float scaleX, float scaleY, float centerX, float centerY)
	Combine the current transform with a scaling.
Transform &	scale (const Vector2f &factors)
	Combine the current transform with a scaling.
Transform &	scale (const Vector2f &factors, const Vector2f &center)
	Combine the current transform with a scaling.

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

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

Detailed Description

Define a 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));

See also

sf::Transformable, sf::RenderStates

Definition at line 42 of file Transform.hpp.

Constructor & Destructor Documentation

Transform() [1/2]

sf::Transform::Transform

(

)

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
	)

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

)

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

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

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());

Returns

Pointer to a 4x4 matrix

rotate() [1/3]

Transform & sf::Transform::rotate

(

float

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(90).translate(50, 20);

Parameters

angle

Rotation angle, in degrees

Returns

Reference to *this

See also

translate, scale

rotate() [2/3]

Transform & sf::Transform::rotate	(	float	angle,
		const 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(90, sf::Vector2f(8, 3)).translate(sf::Vector2f(50, 20));

Parameters

angle	Rotation angle, in degrees
center	Center of rotation

Returns

Reference to *this

See also

translate, scale

rotate() [3/3]

Transform & sf::Transform::rotate	(	float	angle,
		float	centerX,
		float	centerY
	)

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(90, 8, 3).translate(50, 20);

Parameters

angle	Rotation angle, in degrees
centerX	X coordinate of the center of rotation
centerY	Y coordinate of the center of rotation

Returns

Reference to *this

See also

translate, scale

scale() [1/4]

Transform & sf::Transform::scale

(

const Vector2f &

factors

)

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(45);

Parameters

factors

Scaling factors

Returns

Reference to *this

See also

translate, rotate

scale() [2/4]

Transform & sf::Transform::scale	(	const Vector2f &	factors,
		const Vector2f &	center
	)

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

scale() [3/4]

Transform & sf::Transform::scale	(	float	scaleX,
		float	scaleY
	)

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(2, 1).rotate(45);

Parameters

scaleX	Scaling factor on the X axis
scaleY	Scaling factor on the Y axis

Returns

Reference to *this

See also

translate, rotate

scale() [4/4]

Transform & sf::Transform::scale	(	float	scaleX,
		float	scaleY,
		float	centerX,
		float	centerY
	)

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(2, 1, 8, 3).rotate(45);

Parameters

scaleX	Scaling factor on X axis
scaleY	Scaling factor on Y axis
centerX	X coordinate of the center of scaling
centerY	Y coordinate of the center of scaling

Returns

Reference to *this

See also

translate, rotate

transformPoint() [1/2]

Vector2f sf::Transform::transformPoint

(

const Vector2f &

point

)

const

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

transformPoint() [2/2]

Vector2f sf::Transform::transformPoint	(	float	x,
		float	y
	)		const

Transform a 2D point.

These two statements are equivalent:

sf::Vector2f transformedPoint = matrix.transformPoint(x, y);
sf::Vector2f transformedPoint = matrix * sf::Vector2f(x, y);

Parameters

x	X coordinate of the point to transform
y	Y coordinate of the point to transform

Returns

Transformed point

transformRect()

FloatRect sf::Transform::transformRect

(

const FloatRect &

rectangle

)

const

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() [1/2]

Transform & sf::Transform::translate

(

const Vector2f &

offset

)

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(45);

Parameters

offset

Translation offset to apply

Returns

Reference to *this

See also

rotate, scale

translate() [2/2]

Transform & sf::Transform::translate	(	float	x,
		float	y
	)

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(100, 200).rotate(45);

Parameters

x	Offset to apply on X axis
y	Offset to apply on Y axis

Returns

Reference to *this

See also

rotate, scale

Friends And Related Function 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, const 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 372 of file Transform.hpp.

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

• Transform.hpp