New targetting code; for now for reaching and Fire Storm.

directn.cc tried to assume everything is a beam, this make it impossible
to properly visualise spells/effects with different rules, like reaching,
clouds, IOOD, shotgun-targetted spells, cones, etc.  This interface lets
every spell come with an object that answers the question: if I aim at X,
will location Y be affected?

There are three levels of aiming effect now:
* tracer only
* might be affected
* will be affected unless you miss

This means we can show spells that have randomized area: Freezing Cloud,
Fire Storm's radius, etc.

TODO: display in tiles.

The old targetter has a great number of special cases, I did not replace
it yet since it would be a large amount of work.  The new code allows for
showing explosions and bounces, but I'd start with clouds and such first.
Fire Storm is a good sample.

Also, this commit fixes the targetter not allowing you to reach sqrt(8) via
'f' or '.'; you had to use '!' to do that.  A number of places in the code
assumed that, with a special distinction for two modes of reaching.

1 files changed, 73 insertions, 0 deletions

diff --git a/crawl-ref/source/target.h b/crawl-ref/source/target.h
new file mode 100644
index 0000000000..998c4abcca
--- /dev/null
+++ b/crawl-ref/source/target.h
@@ -0,0 +1,73 @@
+#ifndef TARGET_H
+#define TARGET_H
+
+#include "beam.h"
+
+enum aff_type // sign and non-zeroness matters
+{
+    AFF_TRACER = -1,
+    AFF_NO      = 0,
+    AFF_MAYBE   = 1, // can possibly affect
+    AFF_YES,         // intended/likely to affect
+    // If you want to extend this to pass the probability somehow, feel free to,
+    // just keep AFF_YES the minimal "bright" value.
+};
+
+class targetter
+{
+public:
+    virtual ~targetter() {};
+
+    coord_def origin;
+    coord_def aim;
+    const actor* agent;
+
+    virtual bool set_aim(coord_def a);
+    virtual bool valid_aim(coord_def a) = 0;
+
+    virtual aff_type is_affected(coord_def loc) = 0;
+};
+
+class targetter_beam : public targetter
+{
+public:
+    targetter_beam(const actor *act, int range, beam_type flavour, bool stop);
+    bolt beam;
+    bool set_aim(coord_def a);
+    bool valid_aim(coord_def a);
+    aff_type is_affected(coord_def loc);
+};
+
+class targetter_view : public targetter
+{
+public:
+    targetter_view();
+    bool valid_aim(coord_def a);
+    aff_type is_affected(coord_def loc);
+};
+
+class targetter_smite : public targetter
+{
+public:
+    targetter_smite(const actor *act, int range = LOS_RADIUS,
+                    int exp_min = 0, int exp_max = 0);
+    bool set_aim(coord_def a);
+    bool valid_aim(coord_def a);
+    aff_type is_affected(coord_def loc);
+private:
+    int range2;
+    // assumes exp_map is valid only if >0, so let's keep it private
+    int exp_range_min, exp_range_max;
+    explosion_map exp_map_min, exp_map_max;
+};
+
+class targetter_reach : public targetter
+{
+public:
+    targetter_reach(const actor* act, reach_type ran = REACH_NONE);
+    reach_type range;
+    bool valid_aim(coord_def a);
+    aff_type is_affected(coord_def loc);
+};
+
+#endif