Hands-on Rust dungeon crawler bug I can't figure out (Amulet of Yala)

@herbert

Hoping someone can point me in the right direction here: I’m working through the book Hands-On Rust and have just written the code required to spawn the Amulet of Yala in the map at the most accessibly distant tile from where the player spawns. It’s supposed to be added in the corner of some random faraway room, like this:

That image is from the book on pg 180. My code, however, has the amulet spawning not in a room but in one of the four corners of the entire map screen. i.e. completely unreachable:

image

I combed through every line of code and compared it to what’s in the author’s official repo (HandsOnRust/WinningAndLosing/winning at main · thebracket/HandsOnRust · GitHub) but can’t see what my mistake is. I finally just copied the code from all the files I touched for this Amulet of Yala task to ensure it’s identical, but the amulet is still spawning in a screen corner out of reach. The only files I edited for this are winning/src/components.rs winning/src/spawner.rs winning/src/map_builder.rs winning/src/main.rs winning/src/turn_state.rs and 'winning/src/end_turn.rs. I’m pretty sure the error involves map_builder.rs because it’s the Dijkstra map code that is determining the distance/placement of the amulet in relation to the player:

Anyway, I created a Github repository of all my code in case someone is willing, able, and kind enough to have a look. https://github.com/pudgyturtle/dungeoncrawl I’m reluctant to suggest it’s a bug or error with the book because so far every error I’ve had has been my own typo or oversight, but this one has me super stumped. I’d appreciate any suggestions or help!

1 Like

@herbert

I’ll start by saying that I compared your code to my older commit and I didn’t see anything wrong with your code. I verified that mine was working and yours wasn’t. I did some debugging and found that yours is always positioned in one of the 4 corners. Specifically in:
idx [ dist ] point
0 [62]: Point { x: 0, y: 0 }
79 [97]: Point { x: 79, y: 0 }
3920 [31]: Point { x: 0, y: 49 }
3999 [66]: Point { x: 79, y: 49 }

I also verified that all 4 corners are always walls, as they should be since all four edges are walls.

As a test, I added this to the mb.amulet_start function:

                .filter(|(idx, dist)| {
                    match mb.map.tiles[*idx] {
                        TileType::Floor => {
                            true
                        },
                        TileType::Wall => {
                            false
                        },
                    }
                })

This resulted in the amulet being reachable.

That being said, I don’t have that code snippet in mine - but maybe that will help you track it down.

Thank you so much for looking into this! Smart fix. I’m going to add this snippet for now so I can continue with the book.

I’m glad to hear it’s not something obvious though, so I’ll keep investigating and try to see if I can get to the bottom of what the problem is. Maybe some minor change to one of the linked crates being used?

Update here for anyone else running into this issue like me:

Eventually, after continuing with the book, you end up restructuring the way rooms are generated and the amulet is spawned so the code fix above will no longer work. I got to page 259 where you use the amulet code to spawn stairs instead and was finding that they kept ending up in one of the unreachable corners.

After playing around a bit I ended up adding this extra filter method to the map_builder/mod.rs file and it did the trick:

.filter(|(idx, dist)| {
    match self {
        can_enter_tile => {
            true
        }
    }
})

Here’s a screenshot of the code in context so you can find it more easily in the file:
Screenshot 2023-08-17 at 3.17.00 PM