/plug-ins/selection-to-path/spline.c
C | 233 lines | 137 code | 57 blank | 39 comment | 16 complexity | 1b50c6c043394b5ed44ed7ff69d9d6fa MD5 | raw file
- /* 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;
- }