Use floor() instead of static_cast<int> for rounding.

This way the code is less likely to fall over with negative
coordinates.

2 files changed, 28 insertions, 8 deletions

diff --git a/crawl-ref/source/ray.cc b/crawl-ref/source/ray.cc
index d57a8e4058..604d448c80 100644
--- a/crawl-ref/source/ray.cc
+++ b/crawl-ref/source/ray.cc
@@ -8,16 +8,36 @@ REVISION("$Rev$");
 
 #include "ray.h"
 
-#include <cmath>
+#include <math.h>
 
 #include "los.h"
 #include "terrain.h"
 
+int ifloor(double d)
+{
+    return static_cast<int>(floor(d));
+}
+
 ray_def::ray_def(double ax, double ay, double s, int q, int idx)
     : accx(ax), accy(ay), slope(s), quadrant(q), fullray_idx(idx)
 {
 }
 
+int ray_def::x() const
+{
+    return ifloor(accx);
+}
+
+int ray_def::y() const
+{
+    return ifloor(accy);
+}
+
+coord_def ray_def::pos() const
+{
+    return coord_def(x(), y());
+}
+
 double ray_def::reflect(double p, double c) const
 {
     return (c + c - p);
@@ -195,7 +215,7 @@ int ray_def::advance(bool shortest_possible, const coord_def *target)
     // If we want to minimise the number of moves on the ray, look one
     // step ahead and see if we can get a diagonal.
 
-    const coord_def old(static_cast<int>(accx), static_cast<int>(accy));
+    const coord_def old = pos();
     const int ret = raw_advance();
 
     if (ret == 2 || (target && pos() == *target))
@@ -204,7 +224,7 @@ int ray_def::advance(bool shortest_possible, const coord_def *target)
     const double maccx = accx, maccy = accy;
     if (raw_advance() != 2)
     {
-        const coord_def second(static_cast<int>(accx), static_cast<int>(accy));
+        const coord_def second = pos();
         // If we can convert to a diagonal, do so.
         if ((second - old).abs() == 2)
             return (2);
@@ -235,8 +255,8 @@ int ray_def::_find_next_intercept()
         return 1;
     }
 
-    const double xtarget = static_cast<int>(accx) + 1;
-    const double ytarget = static_cast<int>(accy) + 1;
+    const double xtarget = ifloor(accx) + 1;
+    const double ytarget = ifloor(accy) + 1;
     const double xdistance = xtarget - accx;
     const double ydistance = ytarget - accy;
     double distdiff = xdistance * slope - ydistance;
diff --git a/crawl-ref/source/ray.h b/crawl-ref/source/ray.h
index 03e8fc4749..1500f39cfc 100644
--- a/crawl-ref/source/ray.h
+++ b/crawl-ref/source/ray.h
@@ -22,9 +22,9 @@ public:
 public:
     ray_def(double accx = 0.0, double accy = 0.0, double slope = 0.0,
             int quadrant = 0, int fullray_idx = -1);
-    int x() const { return static_cast<int>(accx); }
-    int y() const { return static_cast<int>(accy); }
-    coord_def pos() const { return coord_def(x(), y()); }
+    int x() const;
+    int y() const;
+    coord_def pos() const;
 
     // returns the direction taken (0,1,2)
     int advance(bool shorten = false, const coord_def *p = NULL);