4 Data Structures

4 Rational Points

QuickDraw3D defines three- and four-dimensional rational points as pairs and triples of floating-point numbers, together with a floating-point weight. You'll use the TQ3RationalPoint4D data type for defining control points of rational surfaces and solids. The TQ3RationalPoint4D data type represents homogeneous points in four-dimensional space. To get the equivalent three-dimensional point, divide the point's x, y, and z components by the w component.

typedef struct TQ3RationalPoint3D {
 float    x;
 float    y;
 float    w;
} TQ3RationalPoint3D;
typedef struct TQ3RationalPoint4D {
 float    x;
 float    y;
 float    z;
 float    w;
} TQ3RationalPoint4D;
x The x coordinate (abscissa) of a rational point.
y The y coordinate (ordinate) of a rational point.
z The z coordinate of a rational point.
w The weight of a rational point.

3D Graphics Programming with QuickDraw 3D - 21 OCT 1995

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