Add ability to drop items

src/components.rs

@@ -90,3 +90,8 @@ pub struct WantsToPickupItem {
 pub struct WantsToDrinkPotion {
     pub potion: Entity,
 }
+
+#[derive(Component, Debug, Clone)]
+pub struct WantsToDropItem {
+    pub item: Entity,
+}

src/gui.rs

@@ -247,3 +247,90 @@ pub fn show_inventory(gs: &mut State, ctx: &mut Rltk) -> (ItemMenuResult, Option
         },
     }
 }
+
+pub fn drop_item_menu(gs: &mut State, ctx: &mut Rltk) -> (ItemMenuResult, Option<Entity>) {
+    let player_entity = gs.ecs.fetch::<Entity>();
+    let names = gs.ecs.read_storage::<Name>();
+    let backpack = gs.ecs.read_storage::<InBackpack>();
+    let entities = gs.ecs.entities();
+
+    let inventory = (&backpack, &names)
+        .join()
+        .filter(|item| item.0.owner == *player_entity);
+    let count = inventory.count();
+
+    let mut y = (25 - (count / 2)) as i32;
+    ctx.draw_box(
+        15,
+        y - 2,
+        31,
+        (count + 3) as i32,
+        RGB::named(rltk::WHITE),
+        RGB::named(rltk::BLACK),
+    );
+    ctx.print_color(
+        18,
+        y - 2,
+        RGB::named(rltk::YELLOW),
+        RGB::named(rltk::BLACK),
+        "Drop Which Item?",
+    );
+    ctx.print_color(
+        18,
+        y + count as i32 + 1,
+        RGB::named(rltk::YELLOW),
+        RGB::named(rltk::BLACK),
+        "ESCAPE to cancel",
+    );
+
+    let mut equippable: Vec<Entity> = Vec::new();
+    let mut j = 0;
+    for (entity, _pack, name) in (&entities, &backpack, &names)
+        .join()
+        .filter(|item| item.1.owner == *player_entity)
+    {
+        ctx.set(
+            17,
+            y,
+            RGB::named(rltk::WHITE),
+            RGB::named(rltk::BLACK),
+            rltk::to_cp437('('),
+        );
+        ctx.set(
+            18,
+            y,
+            RGB::named(rltk::YELLOW),
+            RGB::named(rltk::BLACK),
+            97 + j as rltk::FontCharType,
+        );
+        ctx.set(
+            19,
+            y,
+            RGB::named(rltk::WHITE),
+            RGB::named(rltk::BLACK),
+            rltk::to_cp437(')'),
+        );
+
+        ctx.print(21, y, &name.name.to_string());
+        equippable.push(entity);
+        y += 1;
+        j += 1;
+    }
+
+    match ctx.key {
+        None => (ItemMenuResult::NoResponse, None),
+        Some(key) => match key {
+            VirtualKeyCode::Escape => (ItemMenuResult::Cancel, None),
+            _ => {
+                let selection = rltk::letter_to_option(key);
+                if selection > -1 && selection < count as i32 {
+                    return (
+                        ItemMenuResult::Selected,
+                        Some(equippable[selection as usize]),
+                    );
+                }
+                (ItemMenuResult::NoResponse, None)
+            }
+        },
+    }
+}

src/inventory_system.rs

@@ -1,6 +1,6 @@
 use crate::{
     gamelog::GameLog, CombatStats, InBackpack, Name, Position, Potion, WantsToDrinkPotion,
-    WantsToPickupItem,
+    WantsToDropItem, WantsToPickupItem,
 };
 use specs::prelude::*;
 
@@ -91,3 +91,59 @@ impl<'a> System<'a> for PotionUseSystem {
         wants_drink.clear();
     }
 }
+
+pub struct ItemDropSystem {}
+
+impl<'a> System<'a> for ItemDropSystem {
+    type SystemData = (
+        ReadExpect<'a, Entity>,
+        WriteExpect<'a, GameLog>,
+        Entities<'a>,
+        WriteStorage<'a, WantsToDropItem>,
+        ReadStorage<'a, Name>,
+        WriteStorage<'a, Position>,
+        WriteStorage<'a, InBackpack>,
+    );
+
+    fn run(&mut self, data: Self::SystemData) {
+        let (
+            player_entity,
+            mut gamelog,
+            entities,
+            mut wants_drop,
+            names,
+            mut positions,
+            mut backpack,
+        ) = data;
+
+        for (entity, to_drop) in (&entities, &wants_drop).join() {
+            let mut dropper_pos: Position = Position { x: 0, y: 0 };
+            {
+                let dropped_pos = positions.get(entity).unwrap();
+                dropper_pos.x = dropped_pos.x;
+                dropper_pos.y = dropped_pos.y;
+            }
+
+            positions
+                .insert(
+                    to_drop.item,
+                    Position {
+                        x: dropper_pos.x,
+                        y: dropper_pos.y,
+                    },
+                )
+                .expect("Unable to drop item to position");
+
+            backpack.remove(to_drop.item);
+
+            if entity == *player_entity {
+                gamelog.entries.push(format!(
+                    "You drop the {}.",
+                    names.get(to_drop.item).unwrap().name
+                ));
+            }
+        }
+
+        wants_drop.clear();
+    }
+}

src/main.rs

@@ -18,7 +18,7 @@ mod visibility_system;
 pub use components::*;
 use damage_system::DamageSystem;
 pub use gamelog::GameLog;
-use inventory_system::{ItemCollectionSystem, PotionUseSystem};
+use inventory_system::{ItemCollectionSystem, ItemDropSystem, PotionUseSystem};
 pub use map::*;
 use map_indexing_system::MapIndexingSystem;
 use melee_combat_system::MeleeCombatSystem;
@@ -36,6 +36,7 @@ pub enum RunState {
     PlayerTurn,
     MonsterTurn,
     ShowInventory,
+    ShowDropItem,
 }
 
 pub struct State {
@@ -65,6 +66,9 @@ impl State {
         let mut potions = PotionUseSystem {};
         potions.run_now(&self.ecs);
 
+        let mut drop_items = ItemDropSystem {};
+        drop_items.run_now(&self.ecs);
+
         self.ecs.maintain();
     }
 }
@@ -118,6 +122,26 @@ impl GameState for State {
                     }
                 }
             }
+            RunState::ShowDropItem => {
+                let result = gui::drop_item_menu(self, ctx);
+
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let item_entity = result.1.unwrap();
+                        let mut intent = self.ecs.write_storage::<WantsToDropItem>();
+                        intent
+                            .insert(
+                                *self.ecs.fetch::<Entity>(),
+                                WantsToDropItem { item: item_entity },
+                            )
+                            .expect("failed to add intent to drop item");
+
+                        newrunstate = RunState::PlayerTurn;
+                    }
+                }
+            }
         }
 
         {
@@ -169,6 +193,7 @@ fn main() -> rltk::BError {
     gs.ecs.register::<InBackpack>();
     gs.ecs.register::<WantsToPickupItem>();
     gs.ecs.register::<WantsToDrinkPotion>();
+    gs.ecs.register::<WantsToDropItem>();
 
     let map: Map = Map::new_map_rooms_and_corridors();
     let (player_x, player_y) = map.rooms[0].center();

src/player.rs

@@ -101,6 +101,9 @@ pub fn player_input(gs: &mut State, ctx: &mut Rltk) -> RunState {
             // Show inventory
             VirtualKeyCode::I => return RunState::ShowInventory,
 
+            // Show item drop screen
+            VirtualKeyCode::D => return RunState::ShowDropItem,
+
             _ => return RunState::AwaitingInput,
         },
     }