gimp/plug-ins/selection-to-path/vector.c

250 lines
4.0 KiB
C

/* vector.c: vector/point operations.
*
* 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 <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <glib.h>
#include <math.h>
#include <assert.h>
#include "global.h"
#include "config.h"
#include "vector.h"
/* Given the point COORD, return the corresponding vector. */
vector_type
make_vector (const real_coordinate_type c)
{
vector_type v;
v.dx = c.x;
v.dy = c.y;
return v;
}
/* And the converse: given a vector, return the corresponding point. */
real_coordinate_type
vector_to_point (const vector_type v)
{
real_coordinate_type coord;
coord.x = v.dx;
coord.y = v.dy;
return coord;
}
real
magnitude (const vector_type v)
{
return hypot (v.dx, v.dy);
}
vector_type
normalize (const vector_type v)
{
vector_type new_v;
real m = magnitude (v);
assert (m > 0.0);
new_v.dx = v.dx / m;
new_v.dy = v.dy / m;
return new_v;
}
vector_type
Vadd (const vector_type v1, const vector_type v2)
{
vector_type new_v;
new_v.dx = v1.dx + v2.dx;
new_v.dy = v1.dy + v2.dy;
return new_v;
}
real
Vdot (const vector_type v1, const vector_type v2)
{
return v1.dx * v2.dx + v1.dy * v2.dy;
}
vector_type
Vmult_scalar (const vector_type v, const real r)
{
vector_type new_v;
new_v.dx = v.dx * r;
new_v.dy = v.dy * r;
return new_v;
}
/* Given the IN_VECTOR and OUT_VECTOR, return the angle between them in
degrees, in the range zero to 180. */
real
Vangle (const vector_type in_vector, const vector_type out_vector)
{
vector_type v1 = normalize (in_vector);
vector_type v2 = normalize (out_vector);
return my_acosd (Vdot (v2, v1));
}
real_coordinate_type
Vadd_point (const real_coordinate_type c, const vector_type v)
{
real_coordinate_type new_c;
new_c.x = c.x + v.dx;
new_c.y = c.y + v.dy;
return new_c;
}
real_coordinate_type
Vsubtract_point (const real_coordinate_type c, const vector_type v)
{
real_coordinate_type new_c;
new_c.x = c.x - v.dx;
new_c.y = c.y - v.dy;
return new_c;
}
coordinate_type
Vadd_int_point (const coordinate_type c, const vector_type v)
{
coordinate_type a;
a.x = SROUND ((real) c.x + v.dx);
a.y = SROUND ((real) c.y + v.dy);
return a;
}
vector_type
Vabs (const vector_type v)
{
vector_type new_v;
new_v.dx = fabs (v.dx);
new_v.dy = fabs (v.dy);
return new_v;
}
/* Operations on points. */
vector_type
Psubtract (const real_coordinate_type c1, const real_coordinate_type c2)
{
vector_type v;
v.dx = c1.x - c2.x;
v.dy = c1.y - c2.y;
return v;
}
/* Operations on integer points. */
vector_type
IPsubtract (const coordinate_type coord1, const coordinate_type coord2)
{
vector_type v;
v.dx = coord1.x - coord2.x;
v.dy = coord1.y - coord2.y;
return v;
}
coordinate_type
IPsubtractP (const coordinate_type c1, const coordinate_type c2)
{
coordinate_type c;
c.x = c1.x - c2.x;
c.y = c1.y - c2.y;
return c;
}
coordinate_type
IPadd (const coordinate_type c1, const coordinate_type c2)
{
coordinate_type c;
c.x = c1.x + c2.x;
c.y = c1.y + c2.y;
return c;
}
coordinate_type
IPmult_scalar (const coordinate_type c, const int i)
{
coordinate_type a;
a.x = c.x * i;
a.y = c.y * i;
return a;
}
real_coordinate_type
IPmult_real (const coordinate_type c, const real r)
{
real_coordinate_type a;
a.x = c.x * r;
a.y = c.y * r;
return a;
}
boolean
IPequal (const coordinate_type c1, const coordinate_type c2)
{
return c1.x == c2.x && c1.y == c2.y;
}