96 lines
3.4 KiB
C
96 lines
3.4 KiB
C
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/* vector.h: operations on vectors and points.
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*
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* Copyright (C) 1992 Free Software Foundation, Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef VECTOR_H
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#define VECTOR_H
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#include "types.h"
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/* Our vectors are represented as displacements along the x and y axes. */
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typedef struct
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{
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real dx, dy;
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} vector_type;
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/* Consider a point as a vector from the origin. */
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extern vector_type make_vector (const real_coordinate_type);
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/* And a vector as a point, i.e., a displacement from the origin. */
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extern real_coordinate_type vector_to_point (const vector_type);
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/* Definitions for these common operations can be found in any decent
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linear algebra book, and most calculus books. */
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extern real magnitude (const vector_type);
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extern vector_type normalize (const vector_type);
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extern vector_type Vadd (const vector_type, const vector_type);
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extern real Vdot (const vector_type, const vector_type);
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extern vector_type Vmult_scalar (const vector_type, const real);
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extern real Vangle (const vector_type in, const vector_type out);
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/* These operations could have been named `P..._vector' just as well as
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V..._point, so we may as well allow both names. */
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#define Padd_vector Vadd_point
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extern real_coordinate_type Vadd_point
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(const real_coordinate_type, const vector_type);
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#define Psubtract_vector Vsubtract_point
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extern real_coordinate_type Vsubtract_point
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(const real_coordinate_type, const vector_type);
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/* This returns the rounded sum. */
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#define IPadd_vector Vadd_int_point
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extern coordinate_type Vadd_int_point
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(const coordinate_type, const vector_type);
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/* Take the absolute value of both components. */
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extern vector_type Vabs (const vector_type);
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/* Operations on points with real coordinates. It is not orthogonal,
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but more convenient, to have the subtraction operator return a
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vector, and the addition operator return a point. */
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extern vector_type Psubtract
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(const real_coordinate_type, const real_coordinate_type);
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/* These are heavily used in spline fitting, so we define them as macros
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instead of functions. */
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#define Padd(rc1, rc2) \
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((real_coordinate_type) { (rc1).x + (rc2).x, (rc1).y + (rc2).y })
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#define Pmult_scalar(rc, r) \
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((real_coordinate_type) { (rc).x * (r), (rc).y * (r) })
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/* Similarly, for points with integer coordinates; here, a subtraction
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operator that does return another point is useful. */
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extern vector_type IPsubtract
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(const coordinate_type, const coordinate_type);
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extern coordinate_type IPsubtractP
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(const coordinate_type, const coordinate_type);
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extern coordinate_type IPadd
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(const coordinate_type, const coordinate_type);
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extern coordinate_type IPmult_scalar (const coordinate_type, const int);
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extern real_coordinate_type IPmult_real
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(const coordinate_type, const real);
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extern boolean IPequal (const coordinate_type, const coordinate_type);
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#endif /* not VECTOR_H */
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