Add function for making item projectiles.

LUA_API.rst

@@ -999,6 +999,10 @@ Items module
 
   Move the item to the unit inventory. Returns *false* if impossible.
 
+* ``dfhack.items.makeProjectile(item)``
+
+  Turns the item into a projectile, and returns the new object, or *nil* if impossible.
+
 
 Maps module
 -----------

Lua API.html

@@ -1213,6 +1213,9 @@ Returns <em>false</em> in case of error.</p>
 <li><p class="first"><tt class="docutils literal">dfhack.items.moveToInventory(item,unit,use_mode,body_part)</tt></p>
 <p>Move the item to the unit inventory. Returns <em>false</em> if impossible.</p>
 </li>
+<li><p class="first"><tt class="docutils literal">dfhack.items.makeProjectile(item)</tt></p>
+<p>Turns the item into a projectile, and returns the new object, or <em>nil</em> if impossible.</p>
+</li>
 </ul>
 </div>
 <div class="section" id="maps-module">

library/LuaApi.cpp

@@ -80,6 +80,7 @@ distribution.
 #include "df/region_map_entry.h"
 #include "df/flow_info.h"
 #include "df/unit_misc_trait.h"
+#include "df/proj_itemst.h"
 
 #include <lua.h>
 #include <lauxlib.h>
@@ -885,6 +886,12 @@ static bool items_moveToInventory
     return Items::moveToInventory(mc, item, unit, mode, body_part);
 }
 
+static df::proj_itemst *items_makeProjectile(df::item *item)
+{
+    MapExtras::MapCache mc;
+    return Items::makeProjectile(mc, item);
+}
+
 static const LuaWrapper::FunctionReg dfhack_items_module[] = {
     WRAPM(Items, getGeneralRef),
     WRAPM(Items, getSpecificRef),
@@ -896,6 +903,7 @@ static const LuaWrapper::FunctionReg dfhack_items_module[] = {
     WRAPN(moveToContainer, items_moveToContainer),
     WRAPN(moveToBuilding, items_moveToBuilding),
     WRAPN(moveToInventory, items_moveToInventory),
+    WRAPN(makeProjectile, items_makeProjectile),
     { NULL, NULL }
 };
 

library/include/modules/Items.h

@@ -44,6 +44,7 @@ distribution.
 namespace df
 {
     struct itemdef;
+    struct proj_itemst;
 }
 
 namespace MapExtras {
@@ -155,5 +156,8 @@ DFHACK_EXPORT bool moveToContainer(MapExtras::MapCache &mc, df::item *item, df::
 DFHACK_EXPORT bool moveToBuilding(MapExtras::MapCache &mc, df::item *item, df::building_actual *building,int16_t use_mode);
 DFHACK_EXPORT bool moveToInventory(MapExtras::MapCache &mc, df::item *item, df::unit *unit,
     df::unit_inventory_item::T_mode mode = df::unit_inventory_item::Carried, int body_part = -1);
+
+/// Detaches the items from its current location and turns it into a projectile
+DFHACK_EXPORT df::proj_itemst *makeProjectile(MapExtras::MapCache &mc, df::item *item);
 }
 }

library/modules/Items.cpp

@@ -72,8 +72,11 @@ using namespace std;
 #include "df/general_ref_contains_itemst.h"
 #include "df/general_ref_contained_in_itemst.h"
 #include "df/general_ref_building_holderst.h"
+#include "df/general_ref_projectile.h"
 #include "df/viewscreen_itemst.h"
 #include "df/vermin.h"
+#include "df/proj_itemst.h"
+#include "df/proj_list_link.h"
 
 #include "df/unit_inventory_item.h"
 #include "df/body_part_raw.h"
@@ -88,6 +91,7 @@ using namespace df::enums;
 using df::global::world;
 using df::global::ui;
 using df::global::ui_selected_unit;
+using df::global::proj_next_id;
 
 #define ITEMDEF_VECTORS \
     ITEM(WEAPON, weapons, itemdef_weaponst) \
@@ -866,3 +870,44 @@ bool DFHack::Items::moveToInventory(
 
     return true;
 }
+
+df::proj_itemst *Items::makeProjectile(MapExtras::MapCache &mc, df::item *item)
+{
+    CHECK_NULL_POINTER(item);
+
+    if (!world || !proj_next_id)
+        return NULL;
+
+    auto pos = getPosition(item);
+    if (!pos.isValid())
+        return NULL;
+
+    auto ref = df::allocate<df::general_ref_projectile>();
+    if (!ref)
+        return NULL;
+
+    if (!detachItem(mc, item))
+    {
+        delete ref;
+        return NULL;
+    }
+
+    item->pos = pos;
+    item->flags.bits.in_job = true;
+
+    auto proj = new df::proj_itemst();
+    proj->link = new df::proj_list_link();
+    proj->link->item = proj;
+    proj->id = (*proj_next_id)++;
+
+    proj->origin_pos = proj->target_pos = pos;
+    proj->cur_pos = proj->prev_pos = pos;
+    proj->item = item;
+
+    ref->projectile_id = proj->id;
+    item->itemrefs.push_back(ref);
+
+    linked_list_append(&world->proj_list, proj->link);
+
+    return proj;
+}