GEO::ArcBall Class Reference

Enables to interactively define a rotation. More...

#include <geogram_gfx/gui/arc_ball.h>

Public Member Functions
	ArcBall ()
	ArcBall constructor.
const mat4 &	get_value () const
	Gets the value of the rotation. More...
void	set_value (const mat4 &value)
	Sets the value of the rotation. More...
bool	get_x_constraint () const
	Tests whether the X axis is constrained. More...
void	set_x_constraint (bool value)
	Specifies whether the X axis is constrained. More...
bool	get_y_constraint () const
	Tests whether the Y axis is constrained. More...
void	set_y_constraint (bool value)
	Specifies whether the Y axis is constrained. More...
void	grab (const vec2 &value)
	Callback called when the mouse is clicked. More...
void	drag (const vec2 &value)
	Callback called when the mouse is moved. More...
void	release (const vec2 &value)
	Callback called when the mouse button is released. More...
void	reset ()
	Resets this ArcBall to the default value.
bool	grabbed () const
	Tests whether this ArcBall is grabbed. More...

Protected Member Functions
vec3	constrain_vector (const vec3 &vector, const vec3 &axis) const
	Discards the component of a vector that is along another vector. More...
vec3	mouse_to_sphere (const vec2 &p)
	Lifts a 2d screen coordinate to 3d sphere coordinates, and applies the X or Y axis constraints. More...

Detailed Description

Enables to interactively define a rotation.

This class is inspired by an implementation written by Paul Rademacher, in his glui library. Initial documentation by Paul Rademacher: A C++ class that implements the Arcball, as described by Ken Shoemake in Graphics Gems IV. This class takes as input mouse events (mouse down, mouse drag, mouse up), and creates the appropriate quaternions and 4x4 matrices to represent the rotation given by the mouse.

Definition at line 66 of file arc_ball.h.

Member Function Documentation

constrain_vector()

vec3 GEO::ArcBall::constrain_vector ( const vec3 &  vector, const vec3 &  axis  ) const

protected

Discards the component of a vector that is along another vector.

Parameters

[in]	vector	the input vector
[in]	axis	the axis along which the component should be discarded

Returns

the projection of vector onto the plane perpendicular to axis

drag()

void GEO::ArcBall::drag

(

const vec2 &

value

)

Callback called when the mouse is moved.

Parameters

[in]

value

the point under the mouse pointer, in normalized device coordinates (x and y both in [-1.0, 1.0]).

get_value()

const mat4& GEO::ArcBall::get_value ( ) const

inline

Gets the value of the rotation.

Returns

the computed rotation, as a 4x4 matrix (with a zero translational component).

Definition at line 78 of file arc_ball.h.

get_x_constraint()

bool GEO::ArcBall::get_x_constraint ( ) const

inline

Tests whether the X axis is constrained.

Return values

true	if the X axis is constrained
false	otherwise

Definition at line 94 of file arc_ball.h.

get_y_constraint()

bool GEO::ArcBall::get_y_constraint ( ) const

inline

Tests whether the Y axis is constrained.

Return values

true	if the Y axis is constrained
false	otherwise

Definition at line 112 of file arc_ball.h.

grab()

void GEO::ArcBall::grab

(

const vec2 &

value

)

Callback called when the mouse is clicked.

Parameters

[in]

value

the picked point, in normalized device coordinates (x and y both in [-1.0, 1.0]).

grabbed()

bool GEO::ArcBall::grabbed ( ) const

inline

Tests whether this ArcBall is grabbed.

Return values

true	if this ArcBall is grabbed.
false	otherwise.

Definition at line 156 of file arc_ball.h.

mouse_to_sphere()

vec3 GEO::ArcBall::mouse_to_sphere ( const vec2 &  p )

protected

Lifts a 2d screen coordinate to 3d sphere coordinates, and applies the X or Y axis constraints.

Parameters

[in]

p

the point, in normalized device coordinates (both X and Y coordinates in [-1.0, 1.0])

Returns

the point lifted on the 3d sphere. X or Y can be constrained to zero according to the status of get_x_constraint() and get_y_constraint() respectively.

release()

void GEO::ArcBall::release

(

const vec2 &

value

)

Callback called when the mouse button is released.

Parameters

[in]

value

the point under the mouse pointer, in normalized device coordinates (x and y both in [-1.0, 1.0]).

set_value()

void GEO::ArcBall::set_value

(

const mat4 &

value

)

Sets the value of the rotation.

Parameters

[in]

value

the rotation, as a 4x4 matrix (with a zero translational component).

set_x_constraint()

void GEO::ArcBall::set_x_constraint ( bool  value )

inline

Specifies whether the X axis is constrained.

Parameters

[in]

value

true if the X axis should be constrained, false otherwise

Definition at line 103 of file arc_ball.h.

set_y_constraint()

void GEO::ArcBall::set_y_constraint ( bool  value )

inline

Specifies whether the Y axis is constrained.

Parameters

[in]

value

true if the Y axis should be constrained, false otherwise

Definition at line 121 of file arc_ball.h.

---

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

• geogram_gfx/gui/arc_ball.h