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/* spline.c: spline and spline list (represented as arrays) manipulation. */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* Def: HAVE_CONFIG_H */
#include "logreport.h"
#include "types.h"
#include "spline.h"
#include "vector.h"
#include "xstd.h"
#include <assert.h>
/* Print a spline in human-readable form. */
void print_spline(spline_type s)
{
assert(SPLINE_DEGREE(s) == LINEARTYPE || SPLINE_DEGREE(s) == CUBICTYPE);
if (SPLINE_DEGREE(s) == LINEARTYPE)
fprintf(stdout, "(%.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) == CUBICTYPE)
fprintf(stdout, "(%.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);
}
/* Evaluate the spline S at a given T value. This is an implementation
of de Casteljau's algorithm. See Schneider's thesis, p.37.
The variable names are taken from there. */
at_real_coord evaluate_spline(spline_type s, gfloat t)
{
spline_type V[4]; /* We need degree+1 splines, but assert degree <= 3. */
signed i, j;
gfloat one_minus_t = (gfloat) 1.0 - t;
polynomial_degree degree = SPLINE_DEGREE(s);
for (i = 0; i <= degree; i++) {
V[0].v[i].x = s.v[i].x;
V[0].v[i].y = s.v[i].y;
V[0].v[i].z = s.v[i].z;
}
for (j = 1; j <= degree; j++)
for (i = 0; i <= degree - j; i++) {
at_real_coord t1 = Pmult_scalar(V[j - 1].v[i], one_minus_t);
at_real_coord t2 = Pmult_scalar(V[j - 1].v[i + 1], t);
at_real_coord temp = Padd(t1, t2);
V[j].v[i].x = temp.x;
V[j].v[i].y = temp.y;
V[j].v[i].z = temp.z;
}
return V[degree].v[0];
}
/* Return a new, empty, spline list. */
spline_list_type *new_spline_list(void)
{
spline_list_type *answer;
XMALLOC(answer, sizeof(spline_list_type));
*answer = empty_spline_list();
return answer;
}
spline_list_type empty_spline_list(void)
{
spline_list_type answer;
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 *new_spline_list_with_spline(spline_type spline)
{
spline_list_type *answer;
answer = new_spline_list();
XMALLOC(SPLINE_LIST_DATA(*answer), sizeof(spline_type));
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)
{
free(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)++;
XREALLOC(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);
XREALLOC(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));
free(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)++;
XREALLOC(SPLINE_LIST_ARRAY_DATA(*l), SPLINE_LIST_ARRAY_LENGTH(*l) * sizeof(spline_list_type));
LAST_SPLINE_LIST_ARRAY_ELT(*l) = s;
}
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