| OCR Text |
Show trans.y, trans.z), a scale factor for each axis (scale.x, scale.y, seal .z) and a radiu . The quadric contains a pointer to the next quadric, so that all quadri an h stored in a dynamically allocated linked list. Each quadric also contains a point r to a structure that specifies surface attributes. A quadric is stored in the data structure shown in Figure 2. A polygon object is defined as a series of vertices (point.x, point.y, point.z), each with an associated surface normal (normal.x, normal.y, normal.z). The polygon contains a pointer to the next polygon, so that all polygons can be stored in a dynamically allocated linked list. Each polygon also contains a pointer to a structure that specifies surface attributes. An additional requirement for polygons is that all the points must be coplanar and the polygon must be convex. Polygons and vertices are stored in the data structure shown in Figure 3. QUADRIC RECORD surface : attributesptr; trans : vector; scale : vector; radius : real; next : quadricptr; END· ' Figure 2: Representation of a Quadric Object |
