Matrix3x3

touchgfx/Matrix3x3.hpp

Class representing a 3x3 matrix of floats. The class is used to define affine transformations for 2D graphics.

Public Classes

struct	Point
	A simple struct containing coordinates.

Public Functions

Matrix3x3::Point	affineTransform(const float x, const float y) const
	Do affine transformation of 2D point.
Matrix3x3::Point	affineTransform(const Matrix3x3::Point & point) const
	Do affine transformation of 2D point.
FORCE_INLINE_FUNCTION float	getElement(int row, int column) const
	Get an element.
FORCE_INLINE_FUNCTION float *	getElements()
	Get the internal matrix elements.
	Matrix3x3()
	Initialize a new instance of the Matrix3x3 class.
Matrix3x3	multiply(const Matrix3x3 & rhs) const
	Multiply with another Matrix3x3.
Matrix3x3::Point	projectiveTransform(const Matrix3x3::Point & point) const
	Do projective transformation of 2D point.
void	reset()
	Reset to identity matrix.
void	rotate(float angleInDegrees)
	Apply rotation transformation.
void	rotatePivot(float angleInDegrees, float x, float y)
	Apply rotation around a pivot point.
void	scale(float scaleX, float scaleY)
	Apply scale transformation.
void	scale(float scaleXY)
	Apply scale transformation.
void	setAffineTransformation(const float transformation[6])
	Sets affine transformation from a row-major matrix.
FORCE_INLINE_FUNCTION void	setElement(int row, int column, float value)
	Set an element.
void	translate(float deltaX, float deltaY)
	Apply translate transformation.

Public Functions Documentation

affineTransform

Matrix3x3::Point affineTransform	(	const float	x ,		const
		const float	y		const
		)	const

Do affine transformation of 2D point.

Affine transformation is a special case of the projective transformation, it has the same properties. However unlike projective transformation, it preserves parallelism.

The Matrix does not include the projective part (g, h, i), see below.

|x'| = |a b c| * |x| |y'| |d e f| |y| |1|

x = x coordinate of the 2D point y = y coordinate of the 2D point x' = x coordinate of the transformed 2D point y' = y coordinate of the transformed 2D point

Parameters:

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

Returns:

The transformed 2D point

affineTransform

Matrix3x3::Point affineTransform	(	const Matrix3x3::Point &	point	)

Do affine transformation of 2D point.

Affine transformation is a special case of the projective transformation, it has the same properties. However unlike projective transformation, it preserves parallelism.

The Matrix does not include the projective part (g, h, i), see below.

|x'| = |a b c| * |x| |y'| |d e f| |y| |1|

x = x coordinate of the 2D point y = y coordinate of the 2D point x' = x coordinate of the transformed 2D point y' = y coordinate of the transformed 2D point

Parameters:

point	2D Point to transform

Returns:

The transformed 2D point

getElement

FORCE_INLINE_FUNCTION float getElement	(	int	row ,		const
		int	column		const
		)	const

Get an element.

Parameters:

row	The row (0-2).
column	The column (0-2).

Returns:

The element.

getElements

FORCE_INLINE_FUNCTION float * getElements	(			)

Get the internal matrix elements.

Return value Internal representation elements[0] <= elements[0][0] elements[1] <= elements[0][1] elements[2] <= elements[0][2] elements[3] <= elements[1][0] elements[4] <= elements[1][1] elements[5] <= elements[1][2] elements[6] <= elements[2][0] elements[7] <= elements[2][1] elements[8] <= elements[2][2]

Returns:

A pointer to the internal matrix elements.

Matrix3x3

Matrix3x3	(			)

Initialize a new instance of the Matrix3x3 class.

The matrix is initialized to the identity matrix.

multiply

Matrix3x3 multiply	(	const Matrix3x3 &	rhs	)

Multiply with another Matrix3x3.

Parameters:

rhs	Right hand side Matrix3x3 to multiply with

Returns:

The resulting Matrix3x3

projectiveTransform

Matrix3x3::Point projectiveTransform	(	const Matrix3x3::Point &	point	)

Do projective transformation of 2D point.

Projective transformation does not preserve parallelism, length, and angle. But it still preserves collinearity and incidence.

The Matrix includes the projective part (g, h, i), see below.

|x'| |a b c| |x/w| |y'| = |d e f| * |y/w| |1 | |g h i| |1/w|

w = gx + hy + i x = x coordinate of the 2D point y = y coordinate of the 2D point x' = x coordinate of the transformed 2D point y' = y coordinate of the transformed 2D point

Parameters:

point	2D Point to transform

Returns:

The transformed 2D point

reset

void reset	(			)

Reset to identity matrix.

rotate

void rotate	(	float	angleInDegrees	)

Apply rotation transformation.

Parameters:

angleInDegrees	Angle to rotate in degrees (positive => clockwise, negative => counterclockwise)

rotatePivot

void rotatePivot	(	float	angleInDegrees ,
		float	x ,
		float	y
		)

Apply rotation around a pivot point.

Parameters:

angleInDegrees	Angle to rotate in degrees (positive => clockwise, negative => counterclockwise)
x	X coordinate of the pivot point.
y	Y coordinate of the pivot point.

Note

This will overwrite the matrix elements set prior to this call.

scale

void scale	(	float	scaleX ,
		float	scaleY
		)

Apply scale transformation.

Parameters:

scaleX	Scale factor in the direction of X
scaleY	Scale factor in the direction of Y

scale

void scale	(	float	scaleXY	)

Apply scale transformation.

Parameters:

scaleXY	Scale factor in the direction of both X and Y

setAffineTransformation

void setAffineTransformation	(	const float	transformation[6]	)

Sets affine transformation from a row-major matrix.

Parameters:

transformation	The transformation.

setElement

FORCE_INLINE_FUNCTION void setElement	(	int	row ,
		int	column ,
		float	value
		)

Set an element.

Parameters:

row	The row.
column	The column.
value	The value.

translate

void translate	(	float	deltaX ,
		float	deltaY
		)

Apply translate transformation.

Parameters:

deltaX	Delta distance in the direction of X
deltaY	Delta distance in the direction of Y