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/* vector.h: operations on vectors and points. */
#ifndef VECTOR_H
#define VECTOR_H
#include "point.h"
#include "exception.h"
/* Our vectors are represented as displacements along the x and y axes. */
typedef struct
{
float dx, dy, dz;
} vector_type;
/* Consider a point as a vector from the origin. */
vector_type
make_vector(float_coord const);
/* And a vector as a point, i.e., a displacement from the origin. */
float_coord
vector_to_point(vector_type const);
/* Definitions for these common operations can be found in any decent
linear algebra book, and most calculus books. */
float
magnitude(vector_type const);
vector_type
normalize(vector_type const);
vector_type
Vadd(vector_type const,
vector_type const);
float
Vdot(vector_type const,
vector_type const);
vector_type
Vmult_scalar(vector_type const,
float const);
float
Vangle(vector_type const in,
vector_type const out,
at_exception_type * const exP);
/* These operations could have been named `P..._vector' just as well as
V..._point, so we may as well allow both names. */
#define Padd_vector Vadd_point
float_coord
Vadd_point(float_coord const,
vector_type const);
#define Psubtract_vector Vsubtract_point
float_coord
Vsubtract_point(float_coord const,
vector_type const);
vector_type
Pdirection(float_coord const final,
float_coord const initial);
/* This returns the rounded sum. */
#define IPadd_vector Vadd_int_point
pm_pixelcoord
Vadd_int_point(pm_pixelcoord const c,
vector_type const v);
/* Take the absolute value of both components. */
vector_type
Vabs(vector_type const);
/* Operations on points with real coordinates. It is not orthogonal,
but more convenient, to have the subtraction operator return a
vector, and the addition operator return a point. */
vector_type
Psubtract(float_coord const,
float_coord const);
vector_type
IPsubtract(pm_pixelcoord const coord1,
pm_pixelcoord const coord2);
/* These are heavily used in spline fitting. */
float_coord
Padd(float_coord const,
float_coord const);
float_coord
Pmult_scalar(float_coord const,
float const);
#endif
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