JGraphics Matrix Transformations

The t_jmatrix is one way to represent a transformation. More...

Collaboration diagram for JGraphics Matrix Transformations:

Data Structures
struct	t_jmatrix
	An affine transformation (such as scale, shear, etc). More...
Functions
void	jgraphics_matrix_init (t_jmatrix *x, double xx, double yx, double xy, double yy, double x0, double y0)
	Set a t_jmatrix to an affine transformation.
void	jgraphics_matrix_init_identity (t_jmatrix *x)
	Modify a matrix to be an identity transform.
void	jgraphics_matrix_init_translate (t_jmatrix *x, double tx, double ty)
	Initialize a t_jmatrix to translate (offset) a point.
void	jgraphics_matrix_init_scale (t_jmatrix *x, double sx, double sy)
	Initialize a t_jmatrix to scale (offset) a point.
void	jgraphics_matrix_init_rotate (t_jmatrix *x, double radians)
	Initialize a t_jmatrix to rotate (offset) a point.
void	jgraphics_matrix_translate (t_jmatrix *x, double tx, double ty)
	Apply a translation to an existing matrix.
void	jgraphics_matrix_scale (t_jmatrix *x, double sx, double sy)
	Apply a scaling to an existing matrix.
void	jgraphics_matrix_rotate (t_jmatrix *x, double radians)
	Apply a rotation to an existing matrix.
void	jgraphics_matrix_invert (t_jmatrix *x)
	Invert an existing matrix.
void	jgraphics_matrix_multiply (t_jmatrix *result, const t_jmatrix *a, const t_jmatrix *b)
	Multiply two matrices: resulting matrix has effect of first applying a and then applying b.
void	jgraphics_matrix_transform_point (const t_jmatrix *matrix, double *x, double *y)
	Transform a point using a t_jmatrix transormation.

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Detailed Description

The t_jmatrix is one way to represent a transformation.

You can use the t_jmatrix in the call to jgraphics_transform(), jgraphics_setmatrix(), and jgraphics_pattern_set_matrix for specifying transformations.

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Function Documentation

void jgraphics_matrix_init	(	t_jmatrix *	x,
		double	xx,
		double	yx,
		double	xy,
		double	yy,
		double	x0,
		double	y0
	)

Set a t_jmatrix to an affine transformation.

Parameters:

x
xx
yx
xy
yy
x0
y0

Remarks:

given x,y the matrix specifies the following transformation:

    xnew = xx * x + xy * y + x0; 
    ynew = yx * x + yy * y + y0;

void jgraphics_matrix_init_identity

(

t_jmatrix *

x

)

Modify a matrix to be an identity transform.

Parameters:

x	The t_jmatrix.

void jgraphics_matrix_init_rotate	(	t_jmatrix *	x,
		double	radians
	)

Initialize a t_jmatrix to rotate (offset) a point.

Parameters:

x	The t_jmatrix.
radians	The angle or rotation in radians.

void jgraphics_matrix_init_scale	(	t_jmatrix *	x,
		double	sx,
		double	sy
	)

Initialize a t_jmatrix to scale (offset) a point.

Parameters:

x	The t_jmatrix.
sx	The horizontal scale factor.
sy	The vertical scale factor.

void jgraphics_matrix_init_translate	(	t_jmatrix *	x,
		double	tx,
		double	ty
	)

Initialize a t_jmatrix to translate (offset) a point.

Parameters:

x	The t_jmatrix.
tx	The amount of x-axis translation.
ty	The amount of y-axis translation.

void jgraphics_matrix_invert

(

t_jmatrix *

x

)

Invert an existing matrix.

Parameters:

x	The t_jmatrix.

void jgraphics_matrix_multiply	(	t_jmatrix *	result,
		const t_jmatrix *	a,
		const t_jmatrix *	b
	)

Multiply two matrices: resulting matrix has effect of first applying a and then applying b.

Parameters:

result	The resulting product t_jmatrix.
a	The first operand.
b	The second operand.

void jgraphics_matrix_rotate	(	t_jmatrix *	x,
		double	radians
	)

Apply a rotation to an existing matrix.

Parameters:

x	The t_jmatrix.
radians	The angle or rotation in radians.

void jgraphics_matrix_scale	(	t_jmatrix *	x,
		double	sx,
		double	sy
	)

Apply a scaling to an existing matrix.

Parameters:

x	The t_jmatrix.
sx	The horizontal scale factor.
sy	The vertical scale factor.

void jgraphics_matrix_transform_point	(	const t_jmatrix *	matrix,
		double *	x,
		double *	y
	)

Transform a point using a t_jmatrix transormation.

Parameters:

matrix	The t_jmatrix.
x	The address of the variable holding the x coordinate.
y	The address of the variable holding the y coordinate.

void jgraphics_matrix_translate	(	t_jmatrix *	x,
		double	tx,
		double	ty
	)

Apply a translation to an existing matrix.

Parameters:

x	The t_jmatrix.
tx	The amount of x-axis translation.
ty	The amount of y-axis translation.