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/* spline.c: spline and spline list (represented as arrays) manipulation. */
#include <assert.h>
#include "mallocvar.h"
#include "message.h"
#include "point.h"
#include "spline.h"
#include "vector.h"
/* Print a spline in human-readable form. */
void
print_spline (FILE *f, spline_type s)
{
assert(SPLINE_DEGREE (s) == LINEARTYPE || SPLINE_DEGREE (s) == CUBICTYPE);
if (SPLINE_DEGREE (s) == LINEARTYPE)
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) == CUBICTYPE)
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);
}
/* 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. */
float_coord
evaluate_spline (spline_type s, float t)
{
spline_type V[4]; /* We need degree+1 splines, but assert degree <= 3. */
signed i, j;
float one_minus_t = (float) 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++)
{
float_coord t1 = Pmult_scalar (V[j - 1].v[i], one_minus_t);
float_coord t2 = Pmult_scalar (V[j - 1].v[i + 1], t);
float_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;
MALLOCVAR(answer);
*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();
MALLOCVAR(SPLINE_LIST_DATA(*answer));
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)
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)++;
REALLOCARRAY(SPLINE_LIST_DATA(*l), SPLINE_LIST_LENGTH(*l));
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);
REALLOCARRAY_NOFAIL(SPLINE_LIST_DATA(*s1), new_length);
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)
free (SPLINE_LIST_ARRAY_DATA (*spline_list_array));
flush_log_output ();
}
/* 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)++;
REALLOCARRAY_NOFAIL(SPLINE_LIST_ARRAY_DATA(*l),
SPLINE_LIST_ARRAY_LENGTH(*l));
LAST_SPLINE_LIST_ARRAY_ELT (*l) = s;
}
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