Just set proper projectile flags

changelog.txt

@@ -38,7 +38,7 @@ Template for new versions:
 - `prioritize`: fix incorrect loading of persisted data on some OS types
 - `list-waves`: no longer gets confused by units that leave the map and then return (e.g. squads who go out on raids)
 - `fix/dead-units`: fix error when removing dead units from burrows and the unit with the greatest ID was dead
-- `gui/autodump`: fix dumping into invalid tiles, creating item projectiles that get destroyed
+- `gui/autodump`: prevent dumping into walls or invalid map area, set proper projectile flags to prevent items from being destroyed
 
 ## Misc Improvements
 - `build-now`: if `suspendmanager` is running, run an unsuspend cycle immediately before scanning for buildings to build

docs/gui/autodump.rst

@@ -11,9 +11,7 @@ you draw boxes around items on the map, it will act on the selected items
 instead. Double-click anywhere on the map to teleport the items there. Be wary
 (or excited) that if you teleport the items into an unsupported position
 (e.g., mid-air), then they will become projectiles and fall. Items may not be
-teleported into walls or fortifications. They may also not be teleported into
-projectile-blocking mid-air buildings (such as water wheels), as this can
-result in unintended item destruction.
+teleported into walls or fortifications.
 
 There are options to include or exclude forbidden items, items that are
 currently tagged as being used by an active job, and items dropped by traders.

gui/autodump.lua

@@ -306,31 +306,6 @@ function Autodump:onRenderFrame(dc, rect)
     end
 end
 
-local function tile_props(pos, tt) --Returns is_ground, is_open_air
-    local shape_attrs = df.tiletype_shape.attrs[df.tiletype.attrs[tt].shape]
-    if shape_attrs.walkable then
-        return true, false --Floor, stair, or ramp
-    elseif shape_attrs.basic_shape == df.tiletype_shape_basic.Wall then
-        return false, false --Wall or fortification
-    end
-
-    local _, occ = dfhack.maps.getTileFlags(pos)
-    if occ.building == df.tile_building_occ.None or
-      occ.building == df.tile_building_occ.Planned or
-      occ.building == df.tile_building_occ.Passable or
-      occ.building == df.tile_building_occ.Well then
-        return false, true --Item can fall safely through; any other may delete item projectile
-    elseif occ.building == df.tile_building_occ.Floored then
-        return true, false --Lowered bridge, forbidden hatch, etc.
-    elseif occ.building == df.tile_building_occ.Dynamic then
-        local bld = dfhack.buildings.findAtTile(pos) --Unforbidden hatch, etc.
-        return (bld and (bld._type == df.building_hatchst or
-            bld._type == df.building_grate_floorst or
-            bld._type == df.building_bars_floorst)), false
-    end
-    return false, false --Don't trust it
-end
-
 function Autodump:do_dump(pos)
     pos = pos or dfhack.gui.getMousePos()
     if not pos then
@@ -344,9 +319,12 @@ function Autodump:do_dump(pos)
         return
     end
 
-    local on_ground, in_air = tile_props(pos, tt)
-    if not (on_ground or in_air) then
-        dfhack.printerr('Dump tile blocked! Can\'t dump on walls, fortifications, or certain mid-air buildings.')
+    local on_ground
+    local shape_attrs = df.tiletype_shape.attrs[df.tiletype.attrs[tt].shape]
+    if shape_attrs.walkable then
+        on_ground = true --Floor, stair, or ramp
+    elseif shape_attrs.basic_shape == df.tiletype_shape_basic.Wall then
+        dfhack.printerr('Dump tile blocked! Can\'t dump on walls or fortifications.')
         return
     end
 
@@ -366,8 +344,14 @@ function Autodump:do_dump(pos)
             if mark_as_forbidden then
                 item.flags.forbid = true
             end
-            if in_air then
-                dfhack.items.makeProjectile(item)
+            if not on_ground then
+                local proj = dfhack.items.makeProjectile(item)
+                proj.flags.no_impact_destroy = true
+                proj.flags.bouncing = true
+                proj.flags.piercing = true
+                proj.flags.parabolic = true
+                proj.flags.no_adv_pause = true
+                proj.flags.no_collide = true
             end
         else
             print(('Could not move item: %s from (%d, %d, %d)'):format(