Rational Points

QuickDraw 3D 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. You'll use the TQ3RationalPoint3D data type to define control points of NURB trim curves.

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.

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© 1997 Apple Computer, Inc.

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