losglobal.cc: A start at tracking LOS globally.

1 files changed, 89 insertions, 0 deletions

diff --git a/crawl-ref/source/losglobal.cc b/crawl-ref/source/losglobal.cc
new file mode 100644
index 0000000000..bd2bb147a4
--- /dev/null
+++ b/crawl-ref/source/losglobal.cc
@@ -0,0 +1,89 @@
+#include "AppHdr.h"
+
+#include "losglobal.h"
+
+#include "coord.h"
+#include "coordit.h"
+#include "fixedarray.h"
+#include "los_def.h"
+
+typedef unsigned char losfield_t;
+typedef FixedArray<losfield_t, LOS_MAX_RANGE+1, 2*LOS_MAX_RANGE+1> halflos_t;
+const coord_def o_half(0, LOS_MAX_RANGE);
+typedef FixedArray<halflos_t, GXM, GYM> globallos_t;
+
+globallos_t globallos;
+
+static losfield_t* _lookup_globallos(const coord_def& p, const coord_def& q)
+{
+    if (!map_bounds(p) || !map_bounds(q))
+        return (NULL);
+    coord_def diff = q - p;
+    if (diff.rdist() > LOS_MAX_RANGE)
+        return (NULL);
+    // p < q iff p.x < q.x || p.x == q.x && p.y < q.y
+    if (diff < coord_def(0, 0))
+        return (&globallos(q)(-diff+o_half));
+    else
+        return (&globallos(p)(diff+o_half));
+}
+
+static void _save_los(los_def* los, los_type l)
+{
+    const coord_def o = los->get_center();
+    for (radius_iterator ri(o, LOS_MAX_RANGE, C_SQUARE); ri; ++ri)
+    {
+        losfield_t* flags = _lookup_globallos(o, *ri);
+        if (!flags)
+            continue;
+        // XXX: we're assuming that if one type of LOS is updated,
+        //      all will be.
+        *flags &= ~LOS_FLAG_INVALID;
+        if (los->see_cell(*ri))
+            *flags |= l;
+        else
+            *flags &= ~l;
+    }
+}
+
+// Opacity at p has changed.
+void invalidate_los_around(const coord_def& p)
+{
+    const coord_def tl = p - coord_def(LOS_MAX_RANGE, LOS_MAX_RANGE);
+    const coord_def br = p + coord_def(0, LOS_MAX_RANGE);
+    // We're wiping out a little more than required here.
+    for (rectangle_iterator ri(tl, br); ri; ++ri)
+        if (map_bounds(*ri))
+            globallos(*ri).init(LOS_FLAG_INVALID);
+}
+
+void invalidate_los()
+{
+    for (rectangle_iterator ri(0); ri; ++ri)
+        globallos(*ri).init(LOS_FLAG_INVALID);
+}
+
+static void _update_globallos_at(const coord_def& p)
+{
+    los_def los(p, opc_default);
+    los.update();
+    _save_los(&los, LOS_DEFAULT);
+    los.set_opacity(opc_no_trans);
+    los.update();
+    _save_los(&los, LOS_NO_TRANS);
+}
+
+bool cell_see_cell(const coord_def& p, const coord_def& q, los_type l)
+{
+    losfield_t* flags = _lookup_globallos(p, q);
+
+    if (!flags)
+        return (false); // outside range
+
+    if (*flags & LOS_FLAG_INVALID)
+        _update_globallos_at(p);
+
+    ASSERT(!(*flags & LOS_FLAG_INVALID));
+
+    return (*flags & l);
+}