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Redesign vec_bearing to distinguish all directions.

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It now returns the shortest representable vector parallel to its
argument, so it can be used to distinguish between all possible
directions of vector.  This means that the rest of the code can be
more flexible it what it produces.  This makes no change to the
resulting font.
This commit is contained in:
Ben Harris 2013-12-26 13:58:29 +00:00
parent 921cfe9cd1
commit 702db19779
1 changed files with 28 additions and 14 deletions
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42
bedstead.c
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@ -106,6 +106,7 @@
#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define XSIZE 6
@ -1355,18 +1356,31 @@ vec_sub(vec v1, vec v2)
}
static int
gcd(int a, int b)
{
int t;
while (b != 0) {
t = b;
b = a % b;
a = t;
}
return a;
}
/* Return the shortest representable vector parallel to the argument. */
static vec
vec_bearing(vec v)
{
if (v.x == 0 && v.y > 0) return 0;
if (v.x == v.y && v.x > 0) return 1;
if (v.x > 0 && v.y == 0) return 2;
if (v.x == -v.y && v.x > 0) return 3;
if (v.x == 0 && v.y < 0) return 4;
if (v.x == v.y && v.x < 0) return 5;
if (v.x < 0 && v.y == 0) return 6;
if (v.x == -v.y && v.x < 0) return 7;
return -1;
vec ret;
int d = gcd(abs(v.x), abs(v.y));
if (d != 0) {
ret.x = v.x / d;
ret.y = v.y / d;
} else {
ret.x = 0;
ret.y = 0;
}
return ret;
}
/* If p is identical to its successor, remove p. */
@ -1383,8 +1397,8 @@ static int
vec_inline3(vec a, vec b, vec c)
{
return
vec_bearing(vec_sub(b, a)) == vec_bearing(vec_sub(c, b)) &&
vec_bearing(vec_sub(b, a)) != -1;
vec_eqp(vec_bearing(vec_sub(b, a)), vec_bearing(vec_sub(c, b))) &&
!vec_eqp(vec_bearing(vec_sub(b, a)), zero);
}
/* Are a, b, c, and d distinct collinear points in that order? */
@ -1421,8 +1435,8 @@ fix_edges(point *a0, point *b0)
assert(a1->prev == a0); assert(b1->prev == b0);
assert(a0 != a1); assert(a0 != b0);
assert(a1 != b1); assert(b0 != b1);
if (vec_bearing(vec_sub(a0->v, a1->v)) ==
vec_bearing(vec_sub(b1->v, b0->v)) &&
if (vec_eqp(vec_bearing(vec_sub(a0->v, a1->v)),
vec_bearing(vec_sub(b1->v, b0->v))) &&
(vec_inline4(a0->v, b1->v, a1->v, b0->v) ||
vec_inline4(a0->v, b1->v, b0->v, a1->v) ||
vec_inline4(b1->v, a0->v, b0->v, a1->v) ||