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GLUI User Interface Toolkit
Copyright (c) 1998 Paul Rademacher
Feb 1998, Paul Rademacher (
Oct 2003, Nigel Stewart - GLUI Code Cleaning
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
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.
This class is used as follows:
- initialize [either in the constructor or with set_params()], the
center position (x,y) of the arcball on the screen, and the radius
- on mouse down, call mouse_down(x,y) with the mouse position
- as the mouse is dragged, repeatedly call mouse_motion() with the
current x and y positions. One can optionally pass in the current
state of the SHIFT, ALT, and CONTROL keys (passing zero if keys
are not pressed, non-zero otherwise), which constrains
the rotation to certain axes (X for CONTROL, Y for ALT).
- when the mouse button is released, call mouse_up()
Axis constraints can also be explicitly set with the
set_constraints() function.
The current rotation is stored in the 4x4 float matrix 'rot'.
It is also stored in the quaternion 'q_now'.
#include "glui_internal.h"
#include "algebra3.h"
#include "quaternion.h"
class Arcball
Arcball(mat4 *mtx);
Arcball(const vec2 &center, float radius);
void set_damping(float d);
void idle();
void mouse_down(int x, int y);
void mouse_up();
void mouse_motion(int x, int y, int shift, int ctrl, int alt);
void mouse_motion(int x, int y);
void set_constraints(bool constrain_x, bool constrain_y);
void set_params(const vec2 &center, float radius);
void reset_mouse();
void init();
vec3 constrain_vector(const vec3 &vector, const vec3 &axis);
vec3 mouse_to_sphere(const vec2 &p);
int is_mouse_down; /* true for down, false for up */
int is_spinning;
quat q_now, q_down, q_drag, q_increment;
vec2 down_pt;
mat4 rot, rot_increment;
mat4 *rot_ptr;
bool constraint_x, constraint_y;
vec2 center;
float radius, damp_factor;
int zero_increment;