Ellipses

An ellipse is a two-dimensional curve defined by an origin (that is, the center of the ellipse) and two vectors that define the major and minor radii of the ellipse. The origin and the two points at the end of the major and minor radii define the plane in which the ellipse lies. An ellipse is defined by the TQ3EllipseData data type. See "Creating and Editing Ellipses" for a description of the routines you can use to create and edit ellipses. Figure 28 shows an ellipse.

Figure 28 An ellipse

typedef struct TQ3EllipseData {
    TQ3Point3D                          origin;
    TQ3Vector3D                         majorRadius;
    TQ3Vector3D                         minorRadius;
    float                               uMin, uMax;
    TQ3AttributeSet                     ellipseAttributeSet;
} TQ3EllipseData;


origin

The origin (that is, the center) of the ellipse.

majorRadius

The major radius of the ellipse.

minorRadius

The minor radius of the ellipse.

uMin

The minimum value in the u parametric direction of the ellipse. This value should be greater than or equal to 0.0 and less than or equal to 1.0.

uMax

The maximum value in the u parametric direction of the ellipse. This value should be greater than or equal to 0.0 and less than or equal to 1.0.

ellipseAttributeSet

A set of attributes for the ellipse. The value in this field is NULL if no ellipse attributes are defined.

---

© 1997 Apple Computer, Inc.

Previous | QD3D Book | Overview | Chapter Contents | Next |