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Patch from James H to make new-Loopy port more easily.

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[originally from svn r8174]
This commit is contained in:
Simon Tatham
2008-09-10 21:44:23 +00:00
parent 018fa4053d
commit acf5c55d35
2 changed files with 38 additions and 26 deletions
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33
grid.c
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@ -50,7 +50,7 @@ void grid_free(grid *g)
/* Used by the other grid generators. Create a brand new grid with nothing
* initialised (all lists are NULL) */
static grid *grid_new()
static grid *grid_new(void)
{
grid *g = snew(grid);
g->faces = NULL;
@ -76,11 +76,11 @@ static grid *grid_new()
*
* Combining gives: distance = determinant / line-length(a,b)
*/
static double point_line_distance(int px, int py,
int ax, int ay,
int bx, int by)
static double point_line_distance(long px, long py,
long ax, long ay,
long bx, long by)
{
int det = ax*by - bx*ay + bx*py - px*by + px*ay - ax*py;
long det = ax*by - bx*ay + bx*py - px*by + px*ay - ax*py;
double len;
det = max(det, -det);
len = sqrt(SQ(ax - bx) + SQ(ay - by));
@ -125,7 +125,7 @@ grid_edge *grid_nearest_edge(grid *g, int x, int y)
for (;;) {
/* Target to beat */
int dist = SQ(cur->x - x) + SQ(cur->y - y);
long dist = SQ((long)cur->x - (long)x) + SQ((long)cur->y - (long)y);
/* Look for nearer dot - if found, store in 'new'. */
grid_dot *new = cur;
int i;
@ -137,10 +137,10 @@ grid_edge *grid_nearest_edge(grid *g, int x, int y)
int j;
if (!f) continue;
for (j = 0; j < f->order; j++) {
int new_dist;
long new_dist;
grid_dot *d = f->dots[j];
if (d == cur) continue;
new_dist = SQ(d->x - x) + SQ(d->y - y);
new_dist = SQ((long)d->x - (long)x) + SQ((long)d->y - (long)y);
if (new_dist < dist) {
new = d;
break; /* found closer dot */
@ -157,23 +157,22 @@ grid_edge *grid_nearest_edge(grid *g, int x, int y)
cur = new;
}
}
/* 'cur' is nearest dot, so find which of the dot's edges is closest. */
best_edge = NULL;
for (i = 0; i < cur->order; i++) {
grid_edge *e = cur->edges[i];
int e2; /* squared length of edge */
int a2, b2; /* squared lengths of other sides */
long e2; /* squared length of edge */
long a2, b2; /* squared lengths of other sides */
double dist;
/* See if edge e is eligible - the triangle must have acute angles
* at the edge's dots.
* Pythagoras formula h^2 = a^2 + b^2 detects right-angles,
* so detect acute angles by testing for h^2 < a^2 + b^2 */
e2 = SQ(e->dot1->x - e->dot2->x) + SQ(e->dot1->y - e->dot2->y);
a2 = SQ(e->dot1->x - x) + SQ(e->dot1->y - y);
b2 = SQ(e->dot2->x - x) + SQ(e->dot2->y - y);
e2 = SQ((long)e->dot1->x - (long)e->dot2->x) + SQ((long)e->dot1->y - (long)e->dot2->y);
a2 = SQ((long)e->dot1->x - (long)x) + SQ((long)e->dot1->y - (long)y);
b2 = SQ((long)e->dot2->x - (long)x) + SQ((long)e->dot2->y - (long)y);
if (a2 >= e2 + b2) continue;
if (b2 >= e2 + a2) continue;
@ -187,9 +186,9 @@ grid_edge *grid_nearest_edge(grid *g, int x, int y)
* Alternatively, we could check that the angle at the point is obtuse.
* That would amount to testing a circular region with the edge as
* diameter. */
dist = point_line_distance(x, y,
e->dot1->x, e->dot1->y,
e->dot2->x, e->dot2->y);
dist = point_line_distance((long)x, (long)y,
(long)e->dot1->x, (long)e->dot1->y,
(long)e->dot2->x, (long)e->dot2->y);
/* Is dist more than half edge length ? */
if (4 * SQ(dist) > e2)
continue;