eliminate a whole slew of unnecessary sqrt() operations

diff --git a/lib/dotgen/dotsplines.c b/lib/dotgen/dotsplines.c
index 1f2cfa1e5dee13b3e5491fae667d2cd66afe4132..c4c7b1a294151118a78de39be214c3fdb455dcee 100644 (file)
--- a/lib/dotgen/dotsplines.c
+++ b/lib/dotgen/dotsplines.c
@@ -87,7 +87,10 @@ static void completeflatpath(path *, pathend_t *, pathend_t *, int, int,
                             int, int, int, box *, box *, int, int);
 static void completeregularpath(path *, Agedge_t *, Agedge_t *,
                                pathend_t *, pathend_t *, box *, int, int);
+#if 0
 static double dist(pointf, pointf);
+#endif
+static double dist2(pointf, pointf);
 static int edgecmp(Agedge_t **, Agedge_t **);
 static Agedge_t *getmainedge(Agedge_t *);
 static box makeflatcomponent(box, box, int, int, int, int, int);
@@ -1325,7 +1328,17 @@ static edge_t *bot_bound(edge_t * e, int side)
     return ans;
 }
 
-static double dist(p, q)
+static double dist2(p, q) /* square of scalar distance between p and q */
+pointf p, q;
+{
+    double d0, d1;
+    d0 = p.x - q.x;
+    d1 = p.y - q.y;
+    return (d0 * d0 + d1 * d1);
+}
+
+#if 0
+static double dist(p, q) /* scalar distance between p and q */
 pointf p, q;
 {
     double d0, d1;
@@ -1333,18 +1346,19 @@ pointf p, q;
     d1 = p.y - q.y;
     return sqrt(d0 * d0 + d1 * d1);
 }
+#endif
 
 point closest(splines * spl, point p)
 {
     int i, j, k, besti, bestj;
-    double bestdist, d, dlow, dhigh;
+    double bestdist2, d2, dlow2, dhigh2;
     double low, high, t;
     pointf c[4], pt2, pt;
     point rv;
     bezier bz;
 
     besti = bestj = -1;
-    bestdist = 1e+38;
+    bestdist2 = 1e+38;
     pt.x = p.x;
     pt.y = p.y;
     for (i = 0; i < spl->size; i++) {
@@ -1354,11 +1368,11 @@ point closest(splines * spl, point p)
 
            b.x = bz.list[j].x;
            b.y = bz.list[j].y;
-           d = dist(b, pt);
-           if ((bestj == -1) || (d < bestdist)) {
+           d2 = dist2(b, pt);
+           if ((bestj == -1) || (d2 < bestdist2)) {
                besti = i;
                bestj = j;
-               bestdist = d;
+               bestdist2 = d2;
            }
        }
     }
@@ -1373,21 +1387,21 @@ point closest(splines * spl, point p)
     }
     low = 0.0;
     high = 1.0;
-    dlow = dist(c[0], pt);
-    dhigh = dist(c[3], pt);
+    dlow2 = dist2(c[0], pt);
+    dhigh2 = dist2(c[3], pt);
     do {
        t = (low + high) / 2.0;
        pt2 = Bezier(c, 3, t, NULL, NULL);
-       if (fabs(dlow - dhigh) < 1.0)
+       if (fabs(dlow2 - dhigh2) < 1.0)
            break;
-       if (low == high)
+       if (high - low < .00001)
            break;
-       if (dlow < dhigh) {
+       if (dlow2 < dhigh2) {
            high = t;
-           dhigh = dist(pt2, pt);
+           dhigh2 = dist2(pt2, pt);
        } else {
            low = t;
-           dlow = dist(pt2, pt);
+           dlow2 = dist2(pt2, pt);
        }
     } while (1);
     rv.x = pt2.x;