Quaternions are used to perform linear algebra rotations. More...

Data Structures
struct	_EPhysics_Quaternion
	Quaternion coordinates and rotation (w, x, y, z) More...

Typedefs
typedef struct _EPhysics_Quaternion	EPhysics_Quaternion
	Quaternion handle, represents a quaternion to be used to rotate bodies.

Functions
EAPI EPhysics_Quaternion *	ephysics_quaternion_new (void)
	Create a new quaternion.

EAPI void	ephysics_quaternion_get (const EPhysics_Quaternion quat, double x, double y, double z, double *w)
	Get quaternion values.

EAPI void	ephysics_quaternion_axis_angle_get (const EPhysics_Quaternion quat, double nx, double ny, double nz, double *a)
	Get quaternion axis and angle.

EAPI void	ephysics_quaternion_set (EPhysics_Quaternion *quat, double x, double y, double z, double w)
	Set quaternion values.

EAPI void	ephysics_quaternion_axis_angle_set (EPhysics_Quaternion *quat, double nx, double ny, double nz, double a)
	Set quaternion using axis angle notation.

EAPI void	ephysics_quaternion_euler_set (EPhysics_Quaternion *quat, double yaw, double pitch, double roll)
	Set quaternion using Euler angles.

EAPI void	ephysics_quaternion_normalize (EPhysics_Quaternion *quat)
	Normalize the quaternion.

EAPI void	ephysics_quaternion_invert (EPhysics_Quaternion *quat)
	Invert the quaternion.

EAPI void	ephysics_quaternion_scale (EPhysics_Quaternion *quat, double scale)
	Scale the quaternion.

EAPI void	ephysics_quaternion_inverse_scale (EPhysics_Quaternion *quat, double scale)
	Inversely scale the quaternion.

EAPI EPhysics_Quaternion *	ephysics_quaternion_sum (const EPhysics_Quaternion quat1, const EPhysics_Quaternion quat2, EPhysics_Quaternion *result)
	Returns a sum of two quaternions.

EAPI EPhysics_Quaternion *	ephysics_quaternion_diff (const EPhysics_Quaternion quat1, const EPhysics_Quaternion quat2, EPhysics_Quaternion *result)
	Returns a difference between two quaternions.

EAPI EPhysics_Quaternion *	ephysics_quaternion_multiply (const EPhysics_Quaternion quat1, const EPhysics_Quaternion quat2, EPhysics_Quaternion *result)
	Multiply two quaternions.

EAPI EPhysics_Quaternion *	ephysics_quaternion_slerp (const EPhysics_Quaternion quat1, const EPhysics_Quaternion quat2, double ratio, EPhysics_Quaternion *result)
	Return the quaternion which is the result of Spherical Linear Interpolation between two quaternions.

EAPI double	ephysics_quaternion_dot (const EPhysics_Quaternion quat1, const EPhysics_Quaternion quat2)
	Return the dot product between two quaternions.

EAPI double	ephysics_quaternion_angle_get (const EPhysics_Quaternion quat1, const EPhysics_Quaternion quat2)
	Return the angle between two quaternions.

EAPI double	ephysics_quaternion_length_get (const EPhysics_Quaternion *quat)
	Return the length of the quaternion.

EAPI double	ephysics_quaternion_length2_get (const EPhysics_Quaternion *quat)
	Return the length squared of the quaternion.

Detailed Description

Quaternions are used to perform linear algebra rotations.

Functions regarding rotation, like ephysics_body_rotation_set() and ephysics_body_rotation_get() would need that. Quaternions can be used to rotate evas maps as well, with evas_map_util_quat_rotate(), but in this case quaternion values need to be get with ephysics_quaternion_get(), since evas don't accept EPhysics_Quaternion type.

A quaternion can be created with ephysics_quaternion_new(), and many operations can be performed with that, as:

Sum: ephysics_quaternion_sum()
Difference: ephysics_quaternion_diff()
Multiple by another quaternion: ephysics_quaternion_multiply()
Multiply by scalar: ephysics_quaternion_scale()
Divide by scalar: ephysics_quaternion_inverse_scale()
Calculate length: ephysics_quaternion_length_get()
Calculate angle between quaternions: ephysics_quaternion_angle_get()

Typedef Documentation

◆ EPhysics_Quaternion

EPhysics_Quaternion

Quaternion handle, represents a quaternion to be used to rotate bodies.

Created with ephysics_quaternion_new() and deleted with free().

Function Documentation

◆ ephysics_quaternion_new()

EAPI EPhysics_Quaternion * ephysics_quaternion_new ( void )

Create a new quaternion.

By default a quaternion is created as identity (w = 1, x = 0, y = 0, z = 0). This values can be modified later by quaternion operations or set directly.

Returns: The created quaternion or NULL on error.

Note: It should be deleted with free() after usage is concluded.

See also: ephysics_quaternion_set();; ephysics_quaternion_axis_angle_set();; ephysics_quaternion_euler_set();; ephysics_quaternion_scale();; ephysics_quaternion_sum();

◆ ephysics_quaternion_get()

EAPI void ephysics_quaternion_get	(	const EPhysics_Quaternion *	quat,
		double *	x,
		double *	y,
		double *	z,
		double *	w
	)

Get quaternion values.

Parameters

quat	Quaternion to get values from.
x	The x coordinate.
y	The y coordinate.
z	The z coordinate.
w	The rotation.

See also: ephysics_quaternion_set();

Examples: test_rotating_forever.c.

◆ ephysics_quaternion_axis_angle_get()

EAPI void ephysics_quaternion_axis_angle_get	(	const EPhysics_Quaternion *	quat,
		double *	nx,
		double *	ny,
		double *	nz,
		double *	a
	)

Get quaternion axis and angle.

Parameters

quat	Quaternion to get values from.
nx	The x component of the axis of rotation.
ny	The y component of the axis of rotation.
nz	The z component of the axis of rotation.
a	The angle of rotation.

See also: ephysics_quaternion_axis_angle_set();; ephysics_quaternion_get();; ephysics_quaternion_set();

◆ ephysics_quaternion_set()

EAPI void ephysics_quaternion_set	(	EPhysics_Quaternion *	quat,
		double	x,
		double	y,
		double	z,
		double	w
	)

Set quaternion values.

Parameters

quat	Quaternion to be set.
x	The x coordinate.
y	The y coordinate.
z	The z coordinate.
w	The rotation.

See also: ephysics_quaternion_get();; ephysics_quaternion_euler_set();

Examples: test_rotating_forever.c.

◆ ephysics_quaternion_axis_angle_set()

EAPI void ephysics_quaternion_axis_angle_set	(	EPhysics_Quaternion *	quat,
		double	nx,
		double	ny,
		double	nz,
		double	a
	)

Set quaternion using axis angle notation.

[w, x, y, z] = [cos(a/2), sin(a/2) * nx, sin(a/2)* ny, sin(a/2) * nz]

Parameters

quat	Quaternion to be set.
nx	The x component of the axis of rotation.
ny	The y component of the axis of rotation.
nz	The z component of the axis of rotation.
a	The angle of rotation.

See also: ephysics_quaternion_axis_angle_get();; ephysics_quaternion_set();; ephysics_quaternion_euler_set();

◆ ephysics_quaternion_euler_set()

EAPI void ephysics_quaternion_euler_set	(	EPhysics_Quaternion *	quat,
		double	yaw,
		double	pitch,
		double	roll
	)

Set quaternion using Euler angles.

It's an alternative to ephysics_quaternion_set() usage. Euler angles will be converted.

Parameters

quat	Quaternion to be set.
yaw	The angle around Y axis.
pitch	The angle around X axis.
roll	The angle around Z axis.

See also: ephysics_quaternion_get();; ephysics_quaternion_set();

◆ ephysics_quaternion_normalize()

EAPI void ephysics_quaternion_normalize ( EPhysics_Quaternion * quat )

Normalize the quaternion.

A normalized quaternion is such that x^2 + y^2 + z^2 + w^2 = 1.

Parameters

quat	Quaternion to be normalized.

Examples: test_rotating_forever.c.

◆ ephysics_quaternion_invert()

EAPI void ephysics_quaternion_invert ( EPhysics_Quaternion * quat )

Invert the quaternion.

Parameters

quat	Quaternion to be inverted.

◆ ephysics_quaternion_scale()

EAPI void ephysics_quaternion_scale	(	EPhysics_Quaternion *	quat,
		double	scale
	)

Scale the quaternion.

Parameters

quat	Quaternion to be scaled.
scale	The scale factor.

See also: ephysics_quaternion_inverse_scale()

◆ ephysics_quaternion_inverse_scale()

EAPI void ephysics_quaternion_inverse_scale	(	EPhysics_Quaternion *	quat,
		double	scale
	)

Inversely scale the quaternion.

Parameters

quat	Quaternion to be scaled.
scale	The scale factor.

See also: ephysics_quaternion_scale()

◆ ephysics_quaternion_sum()

EAPI EPhysics_Quaternion * ephysics_quaternion_sum	(	const EPhysics_Quaternion *	quat1,
		const EPhysics_Quaternion *	quat2,
		EPhysics_Quaternion *	result
	)

Returns a sum of two quaternions.

Parameters

quat1	First quaternion to sum.
quat2	Second quaternion to sum.
result	Quaternion used to store the result. If it's `NULL`, a new quaternion will be allocated (and should be freed after usage).

Returns: The sum quaternion or NULL on error.

◆ ephysics_quaternion_diff()

EAPI EPhysics_Quaternion * ephysics_quaternion_diff	(	const EPhysics_Quaternion *	quat1,
		const EPhysics_Quaternion *	quat2,
		EPhysics_Quaternion *	result
	)

Returns a difference between two quaternions.

Parameters

quat1	First quaternion.
quat2	Second quaternion.
result	Quaternion used to store the result. If it's `NULL`, a new quaternion will be allocated (and should be freed after usage).

Returns: The difference between quat1 and quat2, or NULL on error.

◆ ephysics_quaternion_multiply()

EAPI EPhysics_Quaternion * ephysics_quaternion_multiply	(	const EPhysics_Quaternion *	quat1,
		const EPhysics_Quaternion *	quat2,
		EPhysics_Quaternion *	result
	)

Multiply two quaternions.

Parameters

quat1	First quaternion.
quat2	Second quaternion.
result	Quaternion used to store the result. If it's `NULL`, a new quaternion will be allocated (and should be freed after usage).

Returns: The quat1 multiplied by quat2 on the right, or NULL on error.

Examples: test_rotating_forever.c.

◆ ephysics_quaternion_slerp()

EAPI EPhysics_Quaternion * ephysics_quaternion_slerp	(	const EPhysics_Quaternion *	quat1,
		const EPhysics_Quaternion *	quat2,
		double	ratio,
		EPhysics_Quaternion *	result
	)

Return the quaternion which is the result of Spherical Linear Interpolation between two quaternions.

Slerp interpolates assuming constant velocity.

Parameters

quat1	First quaternion.
quat2	Second quaternion.
ratio	The ratio between `quat1` and `quat2` to interpolate. If `ratio` = 0, the result is `quat1`, if `ratio` = 1, the result is `quat2`.
result	Quaternion used to store the result. If it's `NULL`, a new quaternion will be allocated (and should be freed after usage).

Returns: The result of slerp between quat1 and quat2, or NULL on error.

◆ ephysics_quaternion_dot()

EAPI double ephysics_quaternion_dot	(	const EPhysics_Quaternion *	quat1,
		const EPhysics_Quaternion *	quat2
	)

Return the dot product between two quaternions.

Parameters

quat1	First quaternion.
quat2	Second quaternion.

Returns: The dot product between quat1 and quat2 or 0 on error.

◆ ephysics_quaternion_angle_get()

EAPI double ephysics_quaternion_angle_get	(	const EPhysics_Quaternion *	quat1,
		const EPhysics_Quaternion *	quat2
	)

Return the angle between two quaternions.

Parameters

quat1	First quaternion.
quat2	Second quaternion.

Returns: The angle between quat1 and quat2 or 0 on error.

◆ ephysics_quaternion_length_get()

EAPI double ephysics_quaternion_length_get ( const EPhysics_Quaternion * quat )

Return the length of the quaternion.

Parameters

quat	Quaternion to get length of.

Returns: The length of quat or 0 on error.

◆ ephysics_quaternion_length2_get()

EAPI double ephysics_quaternion_length2_get ( const EPhysics_Quaternion * quat )

Return the length squared of the quaternion.

Parameters

quat	Quaternion to get length of.

Returns: The length of quat or 0 on error.

Data Structures

Typedefs

Functions

Detailed Description

Typedef Documentation

◆ EPhysics_Quaternion

Function Documentation

◆ ephysics_quaternion_new()

◆ ephysics_quaternion_get()

◆ ephysics_quaternion_axis_angle_get()

◆ ephysics_quaternion_set()

◆ ephysics_quaternion_axis_angle_set()

◆ ephysics_quaternion_euler_set()

◆ ephysics_quaternion_normalize()

◆ ephysics_quaternion_invert()

◆ ephysics_quaternion_scale()

◆ ephysics_quaternion_inverse_scale()

◆ ephysics_quaternion_sum()

◆ ephysics_quaternion_diff()

◆ ephysics_quaternion_multiply()

◆ ephysics_quaternion_slerp()

◆ ephysics_quaternion_dot()

◆ ephysics_quaternion_angle_get()

◆ ephysics_quaternion_length_get()

◆ ephysics_quaternion_length2_get()