fp: Add projectile attack

feely_pona_game.h

@@ -22,6 +22,7 @@ enum FP_GameEntityFlag
     FP_GameEntityFlag_PointOfInterestHeart                = 1 << 11,
     FP_GameEntityFlag_CameraTracking                      = 1 << 14,
     FP_GameEntityFlag_BuildZone                           = 1 << 15,
+    FP_GameEntityFlag_TTL                                 = 1 << 16,
 };
 
 enum FP_GameShapeType
@@ -150,6 +151,7 @@ struct FP_GameEntity
     FP_Meters                             sprite_height;
     FP_GameEntityAction                   action;
     FP_Meters                             base_acceleration_per_s;
+    Dqn_V2                                constant_acceleration_per_s;
     Dqn_V2                                velocity;
 
     // Extra animations that are to be executed, but, don't affect the state
@@ -189,6 +191,8 @@ struct FP_GameEntity
     Dqn_V2                                local_pos;
     Dqn_f64                               alive_time_s;
     Dqn_FArray<FP_GameShape, 4>           shapes;
+    Dqn_FArray<FP_GameEntityHandle, 4>    projectiles;
+    uint64_t                              ttl_end_timestamp;
 };
 
 struct FP_GameEntityIterator