prevent players from firing through walls

src/pp/pp.c

@@ -1378,7 +1378,8 @@ P_Space P_SpaceFromWalls(Arena *arena, P_Frame *frame)
   {
     Vec2 p0 = VEC2(wall->start.x / P_TilesPerMeter - P_WorldPitch / 2, wall->start.y / P_TilesPerMeter - P_WorldPitch / 2);
     Vec2 p1 = VEC2(wall->end.x / P_TilesPerMeter - P_WorldPitch / 2, wall->end.y / P_TilesPerMeter - P_WorldPitch / 2);
-    P_Shape shape = P_ShapeFromDesc(.count = 2, .points = { p0, p1 }, .radius = 0.01 );
+    // P_Shape shape = P_ShapeFromDesc(.count = 2, .points = { p0, p1 }, .radius = 0.01 );
+    P_Shape shape = P_ShapeFromDesc(.count = 2, .points = { p0, p1 }, .radius = 0.0 );
     Rng2 aabb = P_BoundingBoxFromShape(shape);
     aabb = AddRng2Vec2(aabb, VEC2(P_WorldPitch / 2.0, P_WorldPitch / 2.0));
     aabb.p0 = FloorVec2(aabb.p0);
@@ -1729,6 +1730,7 @@ void P_SpawnEntsFromList(P_Frame *frame, P_EntList ents)
       dst->next_in_bin = old_next_in_bin;
       dst->prev_in_bin = old_prev_in_bin;
       dst->created_at_ns = frame->time_ns;
+      dst->created_at_tick = frame->tick;
       ++frame->ents_count;
     }
   }
@@ -2717,6 +2719,7 @@ void P_StepFrame(P_Frame *frame)
 
         Vec2 fire_pos = Zi;
         Vec2 fire_dir = Zi;
+        Vec2 fire_base = Zi;
         if (can_fire)
         {
           Vec2 look = firer->control.look;
@@ -2764,6 +2767,13 @@ void P_StepFrame(P_Frame *frame)
           SPR_Ray fire_ray = wep.rays[SPR_RayKind_Ap];
           fire_pos = MulAffineVec2(wep_pix_to_world_af, fire_ray.pos);
           fire_dir = NormRot(MulAffineBasisVec2(wep_pix_to_world_af, fire_ray.dir));
+
+          fire_base = MulVec2(PerpVec2(NegVec2(firer->xf.r)), WedgeVec2(firer->xf.r, SubVec2(firer->xf.t, fire_pos)));
+          fire_base = AddVec2(fire_base, firer->xf.t);
+
+          P_DebugDrawLine(fire_base, fire_pos, Color_Yellow);
+          P_DebugDrawPoint(fire_base, Color_Yellow);
+          P_DebugDrawPoint(fire_pos, Color_Red);
         }
 
         // FIXME: Prevent obstructed weapons from firing through walls
@@ -2795,6 +2805,7 @@ void P_StepFrame(P_Frame *frame)
 
               Vec2 dir = Vec2FromAngle(angle);
 
+              bullet->bullet_base = fire_base;
               bullet->bullet_start = fire_pos;
               bullet->bullet_end = AddVec2(bullet->bullet_start, MulVec2(dir, speed));
               bullet->bullet_firer = firer->key;
@@ -2817,30 +2828,56 @@ void P_StepFrame(P_Frame *frame)
     if (bullet->is_bullet)
     {
       bullet->has_hit = 0;
-      Vec2 ray_start = bullet->bullet_start;
+
-      Vec2 ray_end = bullet->bullet_end;
+      Struct(BulletPath)
-      Vec2 ray_dir = SubVec2(ray_end, ray_start);
+      {
+        BulletPath *next;
+        Vec2 start;
+        Vec2 end;
+      };
+      BulletPath *first_bullet_path = 0;
+      BulletPath *last_bullet_path = 0;
+
+      if (bullet->created_at_tick == frame->tick)
+      {
+        // On bullet's first tick, we want to ensure that the firer/weapon
+        // wasn't obstructed (e.g. to prevent shooting through walls), so we
+        // insert a path from the bullet's base to its starting position before
+        // its actual firing path
+        BulletPath *path = PushStruct(scratch.arena, BulletPath);
+        SllQueuePush(first_bullet_path, last_bullet_path, path);
+        path->start = bullet->bullet_base;
+        path->end = bullet->bullet_start;
+      }
+
+      {
+        BulletPath *path = PushStruct(scratch.arena, BulletPath);
+        SllQueuePush(first_bullet_path, last_bullet_path, path);
+        path->start = bullet->bullet_start;
+        path->end = bullet->bullet_end;
+      }
 
       P_DebugDrawLine(bullet->bullet_start, bullet->bullet_end, Color_Red);
 
+      P_EntKey victim_key = Zi;
+      P_RaycastResult victim_raycast = Zi;
+      {
+        for (BulletPath *path = first_bullet_path; path; path = path->next)
+        {
+          Vec2 path_dir = SubVec2(path->end, path->start);
           P_Space *cast_spaces[] = {
             &world->walls_space,
             &post_solve_ents_space,
           };
-
           P_SpaceEntryList cast_entries = Zi;
           P_UniqueSpaceEntriesFromRay(
             scratch.arena,
             &cast_entries,
             countof(cast_spaces),
             cast_spaces,
-        ray_start,
+            path->start,
-        ray_end
+            path->end
           );
-
-      P_EntKey victim_key = Zi;
-      P_RaycastResult victim_raycast = Zi;
-      {
           f32 closest_len_sq = Inf;
           for (P_SpaceEntryNode *entry_node = cast_entries.first; entry_node; entry_node = entry_node->next)
           {
@@ -2849,17 +2886,17 @@ void P_StepFrame(P_Frame *frame)
             if (!P_MatchEntKey(potential_victim_key, bullet->bullet_firer))
             {
               P_Shape potential_victim_shape = entry->shape;
-            P_RaycastResult entrance_raycast = P_RaycastShape(potential_victim_shape, ray_start, ray_dir);
+              P_RaycastResult entrance_raycast = P_RaycastShape(potential_victim_shape, path->start, path_dir);
               Vec2 entrance = entrance_raycast.p;
               if (entrance_raycast.is_intersecting)
               {
-              P_RaycastResult exit_raycast = P_RaycastShape(potential_victim_shape, ray_start, NegVec2(ray_dir));
+                P_RaycastResult exit_raycast = P_RaycastShape(potential_victim_shape, path->start, NegVec2(path_dir));
                 Vec2 exit = exit_raycast.p;
-              f32 da = DotVec2(ray_dir, SubVec2(entrance, ray_start));
+                f32 da = DotVec2(path_dir, SubVec2(entrance, path->start));
-              f32 db = DotVec2(ray_dir, SubVec2(exit, ray_start));
+                f32 db = DotVec2(path_dir, SubVec2(exit, path->start));
-              if (db > 0 && (da <= Vec2LenSq(ray_dir) || da <= 0))
+                if (db > 0 && (da <= Vec2LenSq(path_dir) || da <= 0))
                 {
-                f32 len_sq = Vec2LenSq(SubVec2(entrance_raycast.p, ray_start));
+                  f32 len_sq = Vec2LenSq(SubVec2(entrance_raycast.p, path->start));
                   if (len_sq < closest_len_sq)
                   {
                     closest_len_sq = len_sq;
@@ -2870,7 +2907,14 @@ void P_StepFrame(P_Frame *frame)
               }
             }
           }
+          if (!P_IsEntKeyNil(victim_key))
+          {
+            // No need to check future paths if this path hit
+            break;
           }
+        }
+      }
+
       P_Ent *victim = P_EntFromKey(frame, victim_key);
 
       // TODO: Truncate bullet trail

src/pp/pp.h

@@ -110,6 +110,7 @@ Struct(P_Ent)
   P_EntKey key;
   u64 rand_seq;
   i64 created_at_ns;
+  i64 created_at_tick;
 
   //- Build data
 
@@ -129,6 +130,7 @@ Struct(P_Ent)
 
   P_EntKey bullet_firer;
   b32 is_bullet;
+  Vec2 bullet_base;
   Vec2 bullet_start;
   Vec2 bullet_end;