A rewrite of losight() to allow future generalization.

Parameters relevant to the LOS calculation are now passed as
an object los_param that takes care of coordinate translation,
bounds checking, opacity of cells and what is written to the
output array.

A check for in_bounds was changed to map_bounds for simlicity;
this should not have any effect.

Special casing for arena was removed from losight; instead
calc_show_los now calls the new losight_permissive.

1 files changed, 88 insertions, 0 deletions

diff --git a/crawl-ref/source/losparam.cc b/crawl-ref/source/losparam.cc
new file mode 100644
index 0000000000..dc22990ee0
--- /dev/null
+++ b/crawl-ref/source/losparam.cc
@@ -0,0 +1,88 @@
+/*
+ *  File:       losparam.h
+ *  Summary:    Parameters for the LOS algorithm 
+ */
+
+#include "AppHdr.h"
+REVISION("$Rev$");
+
+#include "losparam.h"
+
+#include "cloud.h"
+#include "externs.h"
+#include "stuff.h"
+#include "terrain.h"
+
+los_param_trans::los_param_trans(const coord_def& c)
+    : center(c)
+{
+}
+
+coord_def los_param_trans::trans(const coord_def& p) const
+{
+    return p + center;
+}
+
+bool los_param_trans::map_bounds(const coord_def& p) const
+{
+    return ::map_bounds(trans(p));
+}
+
+los_param_base::los_param_base(const coord_def& c)
+    : los_param_trans(c)
+{
+}
+
+dungeon_feature_type los_param_base::feature(const coord_def& p) const
+{
+    return env.grid(trans(p));
+}
+
+unsigned los_param_base::appearance(const coord_def& p) const
+{
+    return grid_appearance(trans(p));
+}
+
+unsigned short los_param_base::cloud_idx(const coord_def& p) const
+{
+    return env.cgrid(trans(p));
+}
+
+opacity_type los_param_base::opacity(const coord_def& p) const
+{
+    dungeon_feature_type f = feature(p);
+    if (grid_is_opaque(f))
+        return OPC_OPAQUE;
+    else if (is_opaque_cloud(cloud_idx(p)))
+        return OPC_HALF;
+    else
+        return OPC_CLEAR;
+}
+
+los_param_compat::los_param_compat(const feature_grid& gr, const coord_def& c,
+                                   bool sb, bool ic)
+    : los_param_base(c), grid(gr), solid_blocks(sb), ignore_clouds(ic)
+{
+}
+
+dungeon_feature_type los_param_compat::feature(const coord_def& p) const
+{
+    return grid(trans(p));
+}
+
+unsigned los_param_compat::appearance(const coord_def& p) const
+{
+    return grid_appearance(grid, trans(p));
+}
+
+opacity_type los_param_compat::opacity(const coord_def& p) const
+{
+    dungeon_feature_type f = feature(p);
+    if (grid_is_opaque(f) || solid_blocks && grid_is_solid(f))
+        return OPC_OPAQUE;
+    else if (!ignore_clouds && is_opaque_cloud(cloud_idx(p)))
+        return OPC_HALF;
+    else
+        return OPC_CLEAR;
+}
+