Implement ranged item attacks

src/components.rs

@@ -108,6 +108,7 @@ pub struct WantsToPickupItem {
 #[derive(Component, Debug)]
 pub struct WantsToUseItem {
     pub item: Entity,
+    pub target: Option<rltk::Point>,
 }
 
 #[derive(Component, Debug, Clone)]
@@ -117,3 +118,13 @@ pub struct WantsToDropItem {
 
 #[derive(Component, Debug)]
 pub struct Consumable {}
+
+#[derive(Component, Debug)]
+pub struct Ranged {
+    pub range: i32,
+}
+
+#[derive(Component, Debug)]
+pub struct InflictsDamage {
+    pub damage: i32,
+}

src/gui.rs

@@ -1,4 +1,6 @@
-use crate::{game_log::GameLog, CombatStats, InBackpack, Map, Name, Player, Position, State};
+use crate::{
+    game_log::GameLog, CombatStats, InBackpack, Map, Name, Player, Position, State, Viewshed,
+};
 use rltk::{Point, Rltk, VirtualKeyCode, RGB};
 use specs::prelude::*;
 
@@ -334,3 +336,62 @@ pub fn drop_item_menu(gs: &mut State, ctx: &mut Rltk) -> (ItemMenuResult, Option
         },
     }
 }
+
+pub fn ranged_target(
+    gs: &mut State,
+    ctx: &mut Rltk,
+    range: i32,
+) -> (ItemMenuResult, Option<Point>) {
+    let player_entity = gs.ecs.fetch::<Entity>();
+    let player_pos = gs.ecs.fetch::<Point>();
+    let viewsheds = gs.ecs.read_storage::<Viewshed>();
+
+    ctx.print_color(
+        5,
+        0,
+        RGB::named(rltk::YELLOW),
+        RGB::named(rltk::BLACK),
+        "Select Target:",
+    );
+
+    // Highlight available target cells
+    let mut available_cells = Vec::new();
+    let visible = viewsheds.get(*player_entity);
+    if let Some(visible) = visible {
+        for idx in visible.visible_tiles.iter() {
+            let distance = rltk::DistanceAlg::Pythagoras.distance2d(*player_pos, *idx);
+            if distance <= range as f32 {
+                ctx.set_bg(idx.x, idx.y, RGB::named(rltk::BLUE));
+                available_cells.push(idx);
+            }
+        }
+    } else {
+        return (ItemMenuResult::Cancel, None);
+    }
+
+    // Draw mouse cursor
+    let mouse_pos = ctx.mouse_pos();
+    let mut valid_target = false;
+    for idx in available_cells.iter() {
+        if idx.x == mouse_pos.0 && idx.y == mouse_pos.1 {
+            valid_target = true;
+        }
+    }
+
+    if valid_target {
+        ctx.set_bg(mouse_pos.0, mouse_pos.1, RGB::named(rltk::CYAN));
+        if ctx.left_click {
+            return (
+                ItemMenuResult::Selected,
+                Some(Point::new(mouse_pos.0, mouse_pos.1)),
+            );
+        }
+    } else {
+        ctx.set_bg(mouse_pos.0, mouse_pos.1, RGB::named(rltk::RED));
+        if ctx.left_click {
+            return (ItemMenuResult::Cancel, None);
+        }
+    }
+
+    (ItemMenuResult::NoResponse, None)
+}

src/inventory_system.rs

@@ -1,6 +1,6 @@
 use crate::{
-    game_log::GameLog, CombatStats, Consumable, InBackpack, Map, Name, Position, ProvidesHealing,
-    WantsToDropItem, WantsToPickupItem, WantsToUseItem,
+    game_log::GameLog, CombatStats, Consumable, InBackpack, InflictsDamage, Map, Name, Position,
+    ProvidesHealing, SufferDamage, WantsToDropItem, WantsToPickupItem, WantsToUseItem,
 };
 use specs::prelude::*;
 
@@ -57,7 +57,9 @@ impl<'a> System<'a> for ItemUseSystem {
         ReadStorage<'a, Name>,
         ReadStorage<'a, Consumable>,
         ReadStorage<'a, ProvidesHealing>,
+        ReadStorage<'a, InflictsDamage>,
         WriteStorage<'a, CombatStats>,
+        WriteStorage<'a, SufferDamage>,
     );
 
     fn run(&mut self, data: Self::SystemData) {
@@ -70,13 +72,20 @@ impl<'a> System<'a> for ItemUseSystem {
             names,
             consumables,
             healing,
+            inflict_damage,
             mut combat_stats,
+            mut suffer_damage,
         ) = data;
 
         for (entity, useitem, stats) in (&entities, &wants_use, &mut combat_stats).join() {
+            let mut used_item = true;
+
+            // If the item heals, apply the healing
             match healing.get(useitem.item) {
                 None => {}
                 Some(healer) => {
+                    used_item = false;
+
                     stats.hp = i32::min(stats.max_hp, stats.hp + healer.heal_amount);
                     if entity == *player_entity {
                         gamelog.entries.push(format!(
@@ -85,9 +94,38 @@ impl<'a> System<'a> for ItemUseSystem {
                             healer.heal_amount
                         ));
                     }
+
+                    used_item = true;
                 }
             }
 
+            // If it inflicts damage, apply it to the target cell
+            match inflict_damage.get(useitem.item) {
+                None => {}
+                Some(damage) => {
+                    let target_point = useitem.target.unwrap();
+                    let idx = map.xy_idx(target_point.x, target_point.y);
+                    used_item = false;
+
+                    for mob in map.tile_content[idx].iter() {
+                        SufferDamage::new_damage(&mut suffer_damage, *mob, damage.damage);
+                        if entity == *player_entity {
+                            let mob_name = names.get(*mob).unwrap();
+                            let item_name = names.get(useitem.item).unwrap();
+
+                            gamelog.entries.push(format!(
+                                "You use {} on {}, inflicting {} hp.",
+                                item_name.name, mob_name.name, damage.damage
+                            ));
+                        }
+
+                        used_item = true;
+                    }
+                }
+            }
+
+            // If it's a consumable, delete it on use
+            if used_item {
                 let consumable = consumables.get(useitem.item);
                 match consumable {
                     None => {}
@@ -98,6 +136,7 @@ impl<'a> System<'a> for ItemUseSystem {
                     }
                 }
             }
+        }
 
         wants_use.clear();
     }

src/main.rs

@@ -48,6 +48,7 @@ pub enum RunState {
     MonsterTurn,
     ShowInventory,
     ShowDropItem,
+    ShowTargeting { range: i32, item: Entity },
 }
 
 pub struct State {
@@ -144,12 +145,22 @@ impl GameState for State {
                     gui::ItemMenuResult::NoResponse => {}
                     gui::ItemMenuResult::Selected => {
                         let item_entity = result.1.unwrap();
+                        let is_ranged = self.ecs.read_storage::<Ranged>();
+                        let is_item_ranged = is_ranged.get(item_entity);
+
+                        if let Some(is_item_ranged) = is_item_ranged {
+                            newrunstate = RunState::ShowTargeting {
+                                range: is_item_ranged.range,
+                                item: item_entity,
+                            };
+                        } else {
                             let mut intent = self.ecs.write_storage::<WantsToUseItem>();
                             intent
                                 .insert(
                                     *self.ecs.fetch::<Entity>(),
                                     WantsToUseItem {
                                         item: item_entity,
+                                        target: None,
                                     },
                                 )
                                 .expect("failed to add intent to use item");
@@ -158,6 +169,7 @@ impl GameState for State {
                         }
                     }
                 }
+            }
             RunState::ShowDropItem => {
                 let result = gui::drop_item_menu(self, ctx);
 
@@ -178,6 +190,28 @@ impl GameState for State {
                     }
                 }
             }
+            RunState::ShowTargeting { range, item } => {
+                let result = gui::ranged_target(self, ctx, range);
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let mut intent = self.ecs.write_storage::<WantsToUseItem>();
+
+                        intent
+                            .insert(
+                                *self.ecs.fetch::<Entity>(),
+                                WantsToUseItem {
+                                    item,
+                                    target: result.1,
+                                },
+                            )
+                            .expect("failed to add intent to use item");
+
+                        newrunstate = RunState::PlayerTurn;
+                    }
+                }
+            }
         }
 
         {
@@ -217,6 +251,8 @@ fn main() -> rltk::BError {
         WantsToUseItem,
         WantsToDropItem,
         Consumable,
+        Ranged,
+        InflictsDamage,
     );
 
     let map = Map::new_map_rooms_and_corridors();

src/spawner.rs

@@ -1,6 +1,6 @@
 use crate::{
-    BlocksTile, CombatStats, Consumable, Item, Monster, Name, Player, Position, ProvidesHealing,
-    Rect, Renderable, Viewshed, MAP_WIDTH,
+    BlocksTile, CombatStats, Consumable, InflictsDamage, Item, Monster, Name, Player, Position,
+    ProvidesHealing, Ranged, Rect, Renderable, Viewshed, MAP_WIDTH,
 };
 use rltk::{RandomNumberGenerator, RGB};
 use specs::prelude::*;
@@ -126,12 +126,12 @@ pub fn spawn_room(ecs: &mut World, room: &Rect) {
         random_monster(ecs, x as i32, y as i32);
     }
 
-    // Actually spawn the potions
+    // Actually spawn the items
     for idx in item_spawn_points.iter() {
         let x = *idx % MAP_WIDTH;
         let y = *idx / MAP_WIDTH;
 
-        health_potion(ecs, x as i32, y as i32);
+        random_item(ecs, x as i32, y as i32);
     }
 }
 
@@ -144,11 +144,39 @@ fn health_potion(ecs: &mut World, x: i32, y: i32) {
             bg: RGB::named(rltk::BLACK),
             render_order: 2,
         })
-        .with(Name {
-            name: "Health Potion".to_string(),
-        })
+        .with(Name::new("Health Potion"))
         .with(Item {})
         .with(Consumable {})
         .with(ProvidesHealing { heal_amount: 8 })
         .build();
 }
+
+fn magic_missile_scroll(ecs: &mut World, x: i32, y: i32) {
+    ecs.create_entity()
+        .with(Position { x, y })
+        .with(Renderable {
+            glyph: rltk::to_cp437(')'),
+            fg: RGB::named(rltk::CYAN),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 2,
+        })
+        .with(Name::new("Magic Missile Scroll"))
+        .with(Item {})
+        .with(Consumable {})
+        .with(Ranged { range: 6 })
+        .with(InflictsDamage { damage: 8 })
+        .build();
+}
+
+fn random_item(ecs: &mut World, x: i32, y: i32) {
+    let roll: i32;
+    {
+        let mut rng = ecs.write_resource::<RandomNumberGenerator>();
+        roll = rng.roll_dice(1, 2);
+    }
+
+    match roll {
+        1 => health_potion(ecs, x, y),
+        _ => magic_missile_scroll(ecs, x, y),
+    }
+}