3D Graphics Programming with QuickDraw 3D 1.5.4

View Angle Aspect Cameras

Labels

ASCII: ViewAngleAspectCamera
Binary: vana ( = 0x76616E61 )

Data Format



 
Float32             fieldOfView

Float32             aspectRatioXtoY

fieldOfView: An angle, specified in radians, that defines the maximum field of view of the camera. The value in this field should lie in the open interval (0, p).
aspectRatioXtoY: The horizontal-to-vertical aspect ratio of the camera. If the value in this field is less than 1.0, the camera's field of view is vertical; otherwise, the camera's field of view is horizontal.

Data Size

Description

A view angle aspect camera is a type of perspective camera defined in terms of a field of view angle and a horizontal-to-vertical aspect ratio. The aspect ratio determines the ratio of the base to the height of the rectangles that define the top and base of the camera's view volume. These rectangles lie in the near and far clipping planes, respectively, are upright in the camera's coordinate system, and are centered at the points of intersection of the line along the camera vector and the clipping planes.

If the aspect ratio is less than 1.0, then the field of view angle is in the x = 0 plane of the camera's coordinate system. Otherwise, the field of view angle is in the y = 0 plane of the camera's coordinate system. In both cases the rays that define the angle intersect in the camera location point, and the field of view angle is bisected by the ray from the camera location defined by the camera vector. The center of projection is the camera location point. The view volume of a view angle aspect camera is symmetrical about its center line. The method of projection determined by a view angle aspect camera has one principal vanishing point, located at the origin of the projection plane.

Parent Hierarchy

Shared, shape, camera.

Parent Objects

View hints (sometimes).

Child Objects

Camera placement, camera view port, camera range (optional). If a camera does not have one of these child objects, then it should be assigned the default values specified in the section on that child object.

Example



 
Container (

    ViewAngleAspectCamera (

        1.7

        1.0

    )

    CameraPlacement ( ... )

    CameraRange ( ... )

    CameraViewPort ( ... )

)