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# openvrml::frustum Class Reference

A view frustum. More...

`#include <openvrml/frustum.h>`

List of all members.

## Public Member Functions

| frustum ()
| Construct a default frustum.
| frustum (float fovy, float aspect, double z_near, double z_far)
| Construct and initialize a frustum.

## Public Attributes

float | fovy
| Vertical field of view.
float | fovx
| Horizontal field of view.
double | z_near
| Distance to the near clipping plane.
double | z_far
| Distance to the far clipping plane.
float | left_plane [4]
| Left (looking down -z) side clip plane.
float | right_plane [4]
| Right clipping plane.
float | top_plane [4]
| Top clipping plane.
float | bot_plane [4]
| Bottom clipping plane.

## Private Member Functions

void | update ()
| Update the plane equations.

## Detailed Description

A view frustum.

A frustum is more or less a truncated pyramid. This class represents frustums with their wide end facing down the -z axis, and their (theoretical) tip at the origin. A frustum is a convenient representation of the volume of virtual space visible through the on-screen window when using a perspective projection.

See also:
  openvrml::appearance_node::render_appearance
  openvrml::child_node::render_child
  openvrml::geometry_node::render_geometry
  openvrml::viewer

## Constructor & Destructor Documentation

openvrml::frustum::frustum | ( |  | ) |

Construct a default frustum.

fovy, fovx, near and far all get set to -1.

openvrml::frustum::frustum | ( | float | fovy,
|  | float | aspect,
|  | double | z_near,
|  | double | z_far |
| ) |  |  |

Construct and initialize a frustum.

The field of view should be less than 180 degrees. Extreme aspect ratios are unlikely to work well. The near and far plane distances are always positive (think distance, not position). anear must be less than afar. This is supposed to look like gluPerspective.

Parameters:

  `[in]` | fovy | vertical field of view in degrees.
  `[in]` | aspect | ratio of view width to height (not the ratio of the horizontal to vertial field-of-views).
  `[in]` | z_near | distance to near clip plane.
  `[in]` | z_far | distance to far clip plane.

## Member Function Documentation

void openvrml::frustum::update | ( |  | ) | `[private]`

Update the plane equations.

The plane equations are derived from the other members.

## Member Data Documentation

openvrml::frustum::fovy

Vertical field of view.

openvrml::frustum::fovx

Horizontal field of view.

openvrml::frustum::z_near

Distance to the near clipping plane.

openvrml::frustum::z_far

Distance to the far clipping plane.

openvrml::frustum::left_plane

Left (looking down -z) side clip plane.

Format is (a,b,c,d) where (a,b,c) is the plane normal and d is the plane offset. For the momement the eyepoint is always the origin, so d is going to be 0.

openvrml::frustum::right_plane

Right clipping plane.

openvrml::frustum::top_plane

Top clipping plane.

openvrml::frustum::bot_plane

Bottom clipping plane.