Add grenade trajectory, RPG armour priority, empty chargers, mega gravity gun

- Projectiles gets a "Grenade trajectory" toggle. While a frag grenade is
  held, simulate the weapon_frag throw (1200 u/s forward + 120 z, player
  velocity, gravity 600) and trace each step with a new
  trace_solid_segment(); reflect on impact, stop on a slow upward-normal hit,
  and draw the path, landing cross and a 300-unit blast ring. Verified on :99
  (arcs, bounces off the tunnel wall, lands).
- With the RPG equipped, armoured NPCs (striders, gunships, dropships,
  hunter-choppers) sort before normal enemies during target acquisition.
  Added helicopter/chopper to the ARMORED model list.
- Empty health/suit chargers are hidden: read m_iJuice from the server
  datamap (0 = depleted, -1 = unreadable/fail open).
- The citadel supercharged gravity gun (d3_citadel_03, d3_citadel_04,
  d3_breen_01 via IVEngineClient::GetLevelName) is treated as a normal
  weapon, so the melee aimbot no longer restricts it to VULNERABLE NPCs.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/vischeck.cpp b/src/vischeck.cpp
index c8c0942..6b531b9 100644
--- a/src/vischeck.cpp
+++ b/src/vischeck.cpp
@@ -232,6 +232,27 @@ void *trace_entity(const Vector &start, const Vector &end, void *ignore) {
   return tr.ent;
 }
 
+// First solid/world hit along a segment, for grenade bounce prediction.
+// Returns false on a clear path; otherwise fills the impact point and normal.
+bool trace_solid_segment(const Vector &start, const Vector &end, void *ignore,
+                         Vector &out_end, Vector &out_normal) {
+  if (!g_iface.enginetrace)
+    return false;
+  RayCompat ray;
+  make_ray(ray, start, end);
+  GameTraceCompat tr{};
+  EntityFilter filter(ignore);
+  using TraceRayFn = void (*)(void *, const RayCompat *, unsigned, void *,
+                              GameTraceCompat *);
+  vfunc<TraceRayFn>(g_iface.enginetrace, 4)(g_iface.enginetrace, &ray,
+                                            MASK_PLAYERSOLID, &filter, &tr);
+  if (tr.startsolid || tr.fraction >= 1.0f)
+    return false;
+  out_end = tr.endpos;
+  out_normal = tr.normal;
+  return true;
+}
+
 // True when a downward point trace from just above `point` finds a standable
 // surface. Used by edge jump: a ledge has no floor within the probe, slopes and
 // stairs do.