---

ViewModel Class Reference

The ViewModel class implements a camera model, minus the perspective transformation. More...

Public Methods
void	set_distance (float new_distance)
void	set_up (vec3 new_up)
void	set_up (float x, float y, float z)
void	set_eye (vec3 new_eye)
void	set_eye (float x, float y, float z)
void	set_lookat (vec3 new_lookat)
void	set_lookat (float x, float y, float z)
void	roll (float angle)
void	eye_yaw (float angle)
void	eye_yaw_abs (float angle, vec3 axis)
void	eye_pitch (float angle)
void	lookat_yaw (float angle)
void	lookat_pitch (float angle)
void	reset_up (int axis_num)
void	reset_up (void)
void	move (float side_move, float up_move, float forw_move)
void	move (vec3 v)
void	move_by_eye (vec3 new_eye)
void	move_by_lookat (vec3 new_lookat)
void	move_abs (vec3 v)
void	rot_about_eye (mat4 rot)
void	rot_about_lookat (mat4 rot)
void	make_mtx (void)
void	load_to_openGL (void)
void	load_to_openGL_noident (void)
void	reset (void)
	ViewModel (void)
void	update (void)
void	dump (FILE *output)
Data Fields
vec3	eye
	eye point
vec3	lookat
	lookat point
vec3	up
	up vector
vec3	side
	side vector
vec3	forward
	forward vector
mat4	mtx
	modelview matrix
float	distance
	distance between eye and lookat points

---

Detailed Description

The ViewModel class implements a camera model, minus the perspective transformation.

It maintains the coordinate system of the camera as three vectors (forward, up, and side), which are themselves derived from two points (eye and lookat).

Apart from simplifying camera translation, this class provides three rotation methods: yaw (rotation about the up axis), roll (about the forward axis), and pitch (about the side axis). Also, these rotations can take place about the eye (in which case the eye location is fixed but the lookat point changes - like rotating your head), or about the lookat point (in which case your eye rotates around the point of interest).

There is also a routine for rotating the eye about an arbitrary axis, which is quite useful in conjuction with the world up axis.

This class is heavily-dependent on the vec3 class in the file algebra3.h.

The function update() sets the side and forward vectors based on the lookat, eye, and up vectors. Remember to call this function if you change the side or forward directly.

Sample use: ViewModel vm; vm.eye.set( 0.0, 0.0, 20.0 ); vm.lookat.set( 0.0, 0.0, 0.0 ); vm.update(); // updates the three vectors

vm.move( 0.0, 2.0, 0.0 ); // Moves the eye and lookat by 2 units in the world Y direction vm.roll( 5.0 ); // rolls 5 degrees about the forward axis vm.lookat_yaw( -25.0 ); // Yaws about the eye (lookat is fixed) by -25 degrees vm.load_to_openGL(); // Sets OpenGL modelview matrix

.. render ...

---

Constructor & Destructor Documentation

ViewModel::ViewModel (  void    )

Constructor

---

Member Function Documentation

void ViewModel::dump (  FILE *    output )

Prints the contents of this class to a file, typically stdin or stderr

void ViewModel::eye_pitch (  float    angle )

Rotates the eye about the side vector Lookat is unaffected

void ViewModel::eye_yaw (  float    angle )

Rotates the eye about the lookat point, using the up vector Lookat is unaffected

void ViewModel::eye_yaw_abs (  float    angle, vec3    axis )

Rotates the eye about the lookat point, with a specific axis Lookat is unaffected

void ViewModel::load_to_openGL (  void    )

Sets the OpenGL modelview matrix based on the current camera coordinates

void ViewModel::load_to_openGL_noident (  void    )

Multiplies the current camera matrix by the existing openGL modelview matrix. This is same as above function, but does not set the OpenGL matrix to identity first

void ViewModel::lookat_pitch (  float    angle )

Rotates the lookat point about the side vector This assumes the side vector is correct. Eye point is unaffected

void ViewModel::lookat_yaw (  float    angle )

This assumes the up vector is correct. Rotates the lookat about the side vector Eye point is unaffected

void ViewModel::make_mtx (  void    )

Constructs a 4x4 matrix - used by load_to_openGL()

void ViewModel::move (  vec3    v )

Moves a specified distance in the forward, side, and up directions.

void ViewModel::move (  float    side_move, float    up_move, float    forw_move )

Moves a specified distance in the forward, side, and up directions. This function does NOT move by world coordinates. To move by world coords, use the move_abs function.

void ViewModel::move_abs (  vec3    v )

Move the eye and lookat in world coordinates

void ViewModel::move_by_eye (  vec3    new_eye )

Sets the eye point, AND moves the lookat point by the same amount as the eye is moved.

void ViewModel::move_by_lookat (  vec3    new_lookat )

Sets the lookat point, AND moves the eye point by the same amount as the lookat is moved.

void ViewModel::reset (  void    )

Resets the parameters of this class

void ViewModel::reset_up (  void    )

Resets up vector to the Y axis

void ViewModel::reset_up (  int    axis_num )

Resets the up vector to a specified axis (0=X, 1=Y, 2=Z) Also sets the eye point level with the lookat point, along the specified axis

void ViewModel::roll (  float    angle )

Rotates about the forward vector eye and lookat remain unchanged

void ViewModel::rot_about_eye (  mat4    rot )

Rotates the lookat point about the eye, based on a 4x4 (pure) rotation matrix

void ViewModel::rot_about_lookat (  mat4    rot )

Rotates the lookat point about the lookat, based on a 4x4 (pure) rotation matrix

void ViewModel::set_distance (  float    new_distance )

This readjusts the distance from the eye to the lookat (changing the eye point in the process). The lookat point is unaffected.

void ViewModel::set_eye (  float    x, float    y, float    z )

Sets the current eye point

void ViewModel::set_eye (  vec3    new_eye )

Sets the current eye point

void ViewModel::set_lookat (  float    x, float    y, float    z )

Sets the current lookat point

void ViewModel::set_lookat (  vec3    new_lookat )

Sets the current lookat point

void ViewModel::set_up (  float    x, float    y, float    z )

Sets the current up vector

void ViewModel::set_up (  vec3    new_up )

Sets the current up vector

void ViewModel::update (  void    )

updates the view params. Call this after making direct changes to the vectors or points of this class

---

Field Documentation

float ViewModel::distance

distance between eye and lookat points

vec3 ViewModel::eye

eye point

vec3 ViewModel::forward

forward vector

vec3 ViewModel::lookat

lookat point

mat4 ViewModel::mtx

modelview matrix

vec3 ViewModel::side

side vector

vec3 ViewModel::up

up vector

---

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

• viewmodel.h

---