mirror of https://github.com/GNOME/gimp.git
234 lines
6.0 KiB
C
234 lines
6.0 KiB
C
/* spline.c: spline and spline list (represented as arrays) manipulation.
|
|
*
|
|
* 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 <assert.h>
|
|
|
|
#include <glib.h>
|
|
|
|
#include "global.h"
|
|
#include "bounding-box.h"
|
|
#include "spline.h"
|
|
#include "vector.h"
|
|
|
|
/* Return a new spline structure, initialized with (recognizable)
|
|
garbage. */
|
|
|
|
spline_type
|
|
new_spline (void)
|
|
{
|
|
real_coordinate_type coord = { -100.0, -100.0 };
|
|
spline_type spline;
|
|
|
|
START_POINT (spline)
|
|
= CONTROL1 (spline)
|
|
= CONTROL2 (spline)
|
|
= END_POINT (spline)
|
|
= coord;
|
|
SPLINE_DEGREE (spline) = -1;
|
|
SPLINE_LINEARITY (spline) = 0;
|
|
|
|
return spline;
|
|
}
|
|
|
|
|
|
/* Print a spline in human-readable form. */
|
|
|
|
void
|
|
print_spline (FILE *f, spline_type s)
|
|
{
|
|
if (SPLINE_DEGREE (s) == LINEAR)
|
|
fprintf (f, "(%.3f,%.3f)--(%.3f,%.3f).\n",
|
|
START_POINT (s).x, START_POINT (s).y,
|
|
END_POINT (s).x, END_POINT (s).y);
|
|
|
|
else if (SPLINE_DEGREE (s) == CUBIC)
|
|
fprintf (f, "(%.3f,%.3f)..ctrls(%.3f,%.3f)&(%.3f,%.3f)..(%.3f,%.3f).\n",
|
|
START_POINT (s).x, START_POINT (s).y,
|
|
CONTROL1 (s).x, CONTROL1 (s).y,
|
|
CONTROL2 (s).x, CONTROL2 (s).y,
|
|
END_POINT (s).x, END_POINT (s).y);
|
|
|
|
else
|
|
{
|
|
/* FATAL1 ("print_spline: strange degree (%d)", SPLINE_DEGREE (s)); */
|
|
}
|
|
}
|
|
|
|
/* Evaluate the spline S at a given T value. This is an implementation
|
|
of de Casteljau's algorithm. See Schneider's thesis (reference in
|
|
../limn/README), p.37. The variable names are taken from there. */
|
|
|
|
real_coordinate_type
|
|
evaluate_spline (spline_type s, real t)
|
|
{
|
|
spline_type V[4]; /* We need degree+1 splines, but assert degree <= 3. */
|
|
unsigned i, j;
|
|
real one_minus_t = 1.0 - t;
|
|
polynomial_degree degree = SPLINE_DEGREE (s);
|
|
|
|
for (i = 0; i <= degree; i++)
|
|
V[0].v[i] = s.v[i];
|
|
|
|
for (j = 1; j <= degree; j++)
|
|
for (i = 0; i <= degree - j; i++)
|
|
{
|
|
#if defined (__GNUC__)
|
|
real_coordinate_type t1 = Pmult_scalar (V[j - 1].v[i], one_minus_t);
|
|
real_coordinate_type t2 = Pmult_scalar (V[j - 1].v[i + 1], t);
|
|
V[j].v[i] = Padd (t1, t2);
|
|
#else
|
|
/* HB: the above is really nice, but is there any other compiler
|
|
* supporting this ??
|
|
*/
|
|
real_coordinate_type t1;
|
|
real_coordinate_type t2;
|
|
t1.x = V[j - 1].v[i].x * one_minus_t;
|
|
t1.y = V[j - 1].v[i].y * one_minus_t;
|
|
t2.x = V[j - 1].v[i + 1].x * t;
|
|
t2.y = V[j - 1].v[i + 1].y * t;
|
|
V[j].v[i].x = t1.x + t2.x;
|
|
V[j].v[i].y = t1.y + t2.y;
|
|
#endif
|
|
}
|
|
|
|
return V[degree].v[0];
|
|
}
|
|
|
|
|
|
|
|
/* Return a new, empty, spline list. */
|
|
|
|
spline_list_type *
|
|
new_spline_list (void)
|
|
{
|
|
spline_list_type *answer = g_new (spline_list_type, 1);
|
|
|
|
SPLINE_LIST_DATA (*answer) = NULL;
|
|
SPLINE_LIST_LENGTH (*answer) = 0;
|
|
|
|
return answer;
|
|
}
|
|
|
|
|
|
/* Return a new spline list with SPLINE as the first element. */
|
|
|
|
spline_list_type *
|
|
init_spline_list (spline_type spline)
|
|
{
|
|
spline_list_type *answer = g_new (spline_list_type, 1);
|
|
|
|
SPLINE_LIST_DATA (*answer) = g_new (spline_type, 1);
|
|
SPLINE_LIST_ELT (*answer, 0) = spline;
|
|
SPLINE_LIST_LENGTH (*answer) = 1;
|
|
|
|
return answer;
|
|
}
|
|
|
|
|
|
/* Free the storage in a spline list. We don't have to free the
|
|
elements, since they are arrays in automatic storage. And we don't
|
|
want to free the list if it was empty. */
|
|
|
|
void
|
|
free_spline_list (spline_list_type *spline_list)
|
|
{
|
|
if (SPLINE_LIST_DATA (*spline_list) != NULL)
|
|
safe_free ((address *) &(SPLINE_LIST_DATA (*spline_list)));
|
|
}
|
|
|
|
|
|
/* Append the spline S to the list SPLINE_LIST. */
|
|
|
|
void
|
|
append_spline (spline_list_type *l, spline_type s)
|
|
{
|
|
assert (l != NULL);
|
|
|
|
SPLINE_LIST_LENGTH (*l)++;
|
|
SPLINE_LIST_DATA (*l) = g_realloc (SPLINE_LIST_DATA (*l),
|
|
SPLINE_LIST_LENGTH (*l) * sizeof (spline_type));
|
|
LAST_SPLINE_LIST_ELT (*l) = s;
|
|
}
|
|
|
|
|
|
/* Tack the elements in the list S2 onto the end of S1.
|
|
S2 is not changed. */
|
|
|
|
void
|
|
concat_spline_lists (spline_list_type *s1, spline_list_type s2)
|
|
{
|
|
unsigned this_spline;
|
|
unsigned new_length;
|
|
|
|
assert (s1 != NULL);
|
|
|
|
new_length = SPLINE_LIST_LENGTH (*s1) + SPLINE_LIST_LENGTH (s2);
|
|
|
|
SPLINE_LIST_DATA (*s1) = g_realloc(SPLINE_LIST_DATA (*s1),new_length * sizeof(spline_type));
|
|
|
|
for (this_spline = 0; this_spline < SPLINE_LIST_LENGTH (s2); this_spline++)
|
|
SPLINE_LIST_ELT (*s1, SPLINE_LIST_LENGTH (*s1)++)
|
|
= SPLINE_LIST_ELT (s2, this_spline);
|
|
}
|
|
|
|
|
|
/* Return a new, empty, spline list array. */
|
|
|
|
spline_list_array_type
|
|
new_spline_list_array (void)
|
|
{
|
|
spline_list_array_type answer;
|
|
|
|
SPLINE_LIST_ARRAY_DATA (answer) = NULL;
|
|
SPLINE_LIST_ARRAY_LENGTH (answer) = 0;
|
|
|
|
return answer;
|
|
}
|
|
|
|
|
|
/* Free the storage in a spline list array. We don't
|
|
want to free the list if it is empty. */
|
|
|
|
void
|
|
free_spline_list_array (spline_list_array_type *spline_list_array)
|
|
{
|
|
unsigned this_list;
|
|
|
|
for (this_list = 0;
|
|
this_list < SPLINE_LIST_ARRAY_LENGTH (*spline_list_array);
|
|
this_list++)
|
|
free_spline_list (&SPLINE_LIST_ARRAY_ELT (*spline_list_array, this_list));
|
|
|
|
if (SPLINE_LIST_ARRAY_DATA (*spline_list_array) != NULL)
|
|
safe_free ((address *) &(SPLINE_LIST_ARRAY_DATA (*spline_list_array)));
|
|
}
|
|
|
|
|
|
/* Append the spline S to the list SPLINE_LIST_ARRAY. */
|
|
|
|
void
|
|
append_spline_list (spline_list_array_type *l, spline_list_type s)
|
|
{
|
|
SPLINE_LIST_ARRAY_LENGTH (*l)++;
|
|
|
|
SPLINE_LIST_ARRAY_DATA (*l) = g_realloc(SPLINE_LIST_ARRAY_DATA (*l),(SPLINE_LIST_ARRAY_LENGTH (*l))*sizeof(spline_list_type));
|
|
LAST_SPLINE_LIST_ARRAY_ELT (*l) = s;
|
|
}
|