Inside Macintosh: 3D Graphics Programming With QuickDraw 3D /

Chapter 4 - Geometric Objects / Geometric Objects Reference

Data Structures

Simple Polygons

A simple polygon is a closed plane figure defined by a list of vertices. (In other words, a simple polygon is a polygon defined by a single contour.) The edges of a simple polygon should not intersect themselves or you will get unpredictable results when operating on the polygon. In addition, a simple polygon must be convex.

The entire simple polygon can have a set of attributes, and any or all of the vertices defining the polygon can have a set of attributes.

A simple polygon is defined by the TQ3PolygonData data type. See "Creating and Editing Simple Polygons," beginning on page 4-81 for a description of the routines you can use to create and edit simple polygons. Figure 4-13 shows a simple polygon.

Figure 4-13 A simple polygon

typedef struct TQ3PolygonData {
   unsigned long              numVertices;
   TQ3Vertex3D                *vertices;
   TQ3AttributeSet            polygonAttributeSet;
} TQ3PolygonData;

Field Description

numVertices

The number of vertices in the simple polygon. The value of this field must be at least 3.

vertices

A pointer to an array of vertices that define the simple polygon.

polygonAttributeSet

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