Collision Detection

Hands-on Rust — by Herbert Wolverson (57 / 120)

👈 Adding Monsters | TOC | Wrap-Up 👉

If you run around the map, you’ll notice that nothing happens when you hit a monster. Let’s change that by adding collision detection. You’ll write a combat system in Chapter 8, ​Health and Melee Combat​ — for now, walking into a monster will remove it from the dungeon.

Collision detection will be its own system. Add a new file to your project, src/systems/collisions.rs. Don’t forget to add mod collisions; to your src/systems/mod.rs file.

Start collisions.rs with a similar pattern:

EntitiesComponentsAndSystems/dungeonecs/src/systems/collisions.rs

​ ​use​ ​crate​::​prelude​::*;
​ 
​ #[system]
​​①​#[read_component(Point)] 
​ #[read_component(Player)]
​ #[read_component(Enemy)]
​​②​​pub​ ​fn​ ​collisions​(ecs: &​mut​ SubWorld, commands: &​mut​ CommandBuffer) {

​①​
This system requires access to Point, Player, and Enemy.

​②​
Legion can give your system a CommandBuffer. This is a special container to insert instructions for Legion to perform after the system is finished. You’ll use the command buffer to remove entities from the game.

Next, create a variable named player_pos to store the player’s position. You then create the same players query you used in player_input to find just the player’s position. You…