3D Graphics Programming with QuickDraw 3D 1.5.4

Ellipses

Figure 13 shows an ellipse.

Figure 13 An ellipse

Labels

ASCII: Ellipse
Binary: elps ( = 0x656C7073 )

Data Format



 
Vector3D            majorAxis

Vector3D            minorAxis

Point3D             origin

Float32             uMin

Float32             uMax

majorAxis: The (semi-) major axis of the ellipse.
minorAxis: The (semi-) minor axis of the ellipse.
origin: The center of the ellipse.
uMin: Minimum parametric limit value, assuming parametrization of the angle between the major axis and the vector from origin to the circumference. A value of u = 0 corresponds to 0 radians, and u = 1 corresponds to 2 radians. This is used to create partial ellipses. The basic idea is that only the part of the ellipse between uMin and uMax is drawn. For details, see the QD3D documentation or develop magazine, Dec. 96. Must be 0 in Version 1.5.
uMax: Maximum parametric limit value; see uMin above. Must be 1 in Version 1.5.

DATA SIZE

0 or 44

Description

An ellipse is a two-dimensional object defined by an origin (that is, the center of the ellipse) and two orthogonal vectors that define the major and minor radii of the ellipse. The origin and the two endpoints of the major and minor radii define the plane in which the ellipse lies. Attributes may be assigned only to the entire ellipse.

Default Surface Parameterization

None.

Parent Hierarchy

Shared, shape, geometry.

Parent Objects

None.

Child Objects

Attribute set (optional).

Example



 
Ellipse (

    2   0   0           #majorRadius

    0   1   0           #minorRadius

    0   0   0           #origin

    0                   #uMin

    1                   #uMax

)

Default Size

For objects of size 0, the default is shown in the example above.