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Diffstat (limited to 'plug-ins/selection-to-path/vector.h')
| -rw-r--r-- | plug-ins/selection-to-path/vector.h | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/plug-ins/selection-to-path/vector.h b/plug-ins/selection-to-path/vector.h new file mode 100644 index 0000000..bc6c213 --- /dev/null +++ b/plug-ins/selection-to-path/vector.h @@ -0,0 +1,95 @@ +/* vector.h: operations on vectors and points. + * + * Copyright (C) 1992 Free Software Foundation, Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ + +#ifndef VECTOR_H +#define VECTOR_H + +#include "types.h" + +/* Our vectors are represented as displacements along the x and y axes. */ + +typedef struct +{ + real dx, dy; +} vector_type; + + +/* Consider a point as a vector from the origin. */ +extern vector_type make_vector (const real_coordinate_type); + +/* And a vector as a point, i.e., a displacement from the origin. */ +extern real_coordinate_type vector_to_point (const vector_type); + + +/* Definitions for these common operations can be found in any decent + linear algebra book, and most calculus books. */ + +extern real magnitude (const vector_type); +extern vector_type normalize (const vector_type); + +extern vector_type Vadd (const vector_type, const vector_type); +extern real Vdot (const vector_type, const vector_type); +extern vector_type Vmult_scalar (const vector_type, const real); +extern real Vangle (const vector_type in, const vector_type out); + +/* 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 +extern real_coordinate_type Vadd_point + (const real_coordinate_type, const vector_type); + +#define Psubtract_vector Vsubtract_point +extern real_coordinate_type Vsubtract_point + (const real_coordinate_type, const vector_type); + +/* This returns the rounded sum. */ +#define IPadd_vector Vadd_int_point +extern coordinate_type Vadd_int_point + (const coordinate_type, const vector_type); + +/* Take the absolute value of both components. */ +extern vector_type Vabs (const vector_type); + + +/* 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. */ +extern vector_type Psubtract + (const real_coordinate_type, const real_coordinate_type); + +/* These are heavily used in spline fitting, so we define them as macros + instead of functions. */ +#define Padd(rc1, rc2) \ + ((real_coordinate_type) { (rc1).x + (rc2).x, (rc1).y + (rc2).y }) +#define Pmult_scalar(rc, r) \ + ((real_coordinate_type) { (rc).x * (r), (rc).y * (r) }) + +/* Similarly, for points with integer coordinates; here, a subtraction + operator that does return another point is useful. */ +extern vector_type IPsubtract + (const coordinate_type, const coordinate_type); +extern coordinate_type IPsubtractP + (const coordinate_type, const coordinate_type); +extern coordinate_type IPadd + (const coordinate_type, const coordinate_type); +extern coordinate_type IPmult_scalar (const coordinate_type, const int); +extern real_coordinate_type IPmult_real + (const coordinate_type, const real); +extern boolean IPequal (const coordinate_type, const coordinate_type); + +#endif /* not VECTOR_H */ |