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

Chapter 4 - Geometric Objects / Geometric Objects Reference

Data Structures

Tangents

QuickDraw 3D defines the TQ3Tangent2D and TQ3Tangent3D data structures to represent two- and three-dimensional parametric surface tangents. A surface tangent indicates the directions of changing u, v, and w parameters on a surface.

typedef struct TQ3Tangent2D {
   TQ3Vector3D                uTangent;
   TQ3Vector3D                vTangent;
} TQ3Tangent2D;
typedef struct TQ3Tangent3D {
   TQ3Vector3D                uTangent;
   TQ3Vector3D                vTangent;
   TQ3Vector3D                wTangent;
} TQ3Tangent3D;

Field Description

uTangent

The tangent in the u direction.

vTangent

The tangent in the v direction.

wTangent

The tangent in the w direction.