zendril

zendril

Hands-on Rust: spawn entities doesn't honor the frequency (page 276)

While converting to data driven spawning the data specifies that an item (like a dungeon map) has a frequency of 1.

However, when they actually get spawned, it is potentially creating many more of them (or none of them). This appears to be because it is leveraging map_builder.spawn_monsters which is hard coded to

const NUM_MONSTERS: usize = 50;

So that means this code is iterating over the 50 Points, rather than over the number of items in the available_entities:

        spawn_points.iter().for_each(|pt| {
            if let Some(entity) = rng.random_slice_entry(&available_entities) {
                self.spawn_entity(pt, entity, &mut commands);
            }
        });

Did I miss something, or is this indeed what is happening?

First Post!

herbert

herbert

Author of Hands-on Rust

Hi!

With hindsight, I should have used the rand crate’s weighted selection, but this seems to work. NUM_MONSTERS is meant to limit the total number of monsters - the actual weighting happens with available_entities.

At the top of spawn_entities (HandsOnRust/template.rs at main · thebracket/HandsOnRust · GitHub), available_entities is created by first filtering on level (so it only sees entities that can be on the level) and then inserting each entity a number of times equal to its frequency. So an orc with a frequency of 3 would be in available_entities 3 times.

So when random_slice_entry comes along and picks a slice entry, it includes all of the slice entries - including the duplicates. That preserves the weighting by template type.

Hope that makes sense?

Where Next?

Popular Pragmatic Bookshelf topics Top

jimschubert
In Chapter 3, the source for index introduces Config on page 31, followed by more code including tests; Config isn’t introduced until pag...
New
simonpeter
When I try the command to create a pair of migration files I get an error. user=> (create-migration "guestbook") Execution error (Ill...
New
gilesdotcodes
In case this helps anyone, I’ve had issues setting up the rails source code. Here were the solutions: In Gemfile, change gem 'rails' t...
New
patoncrispy
I’m new to Rust and am using this book to learn more as well as to feed my interest in game dev. I’ve just finished the flappy dragon exa...
New
jskubick
I found an issue in Chapter 7 regarding android:backgroundTint vs app:backgroundTint. How to replicate: load chapter-7 from zipfile i...
New
brunogirin
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
New
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
mert
AWDWR 7, page 152, page 153: Hello everyone, I’m a little bit lost on the hotwire part. I didn’t fully understand it. On page 152 @rub...
New
dtonhofer
@parrt In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4....
New
roadbike
From page 13: On Python 3.7, you can install the libraries with pip by running these commands inside a Python venv using Visual Studio ...
New

Other popular topics Top

AstonJ
A thread that every forum needs! Simply post a link to a track on YouTube (or SoundCloud or Vimeo amongst others!) on a separate line an...
New
PragmaticBookshelf
Write Elixir tests that you can be proud of. Dive into Elixir’s test philosophy and gain mastery over the terminology and concepts that u...
New
wolf4earth
@AstonJ prompted me to open this topic after I mentioned in the lockdown thread how I started to do a lot more for my fitness. https://f...
New
AstonJ
SpaceVim seems to be gaining in features and popularity and I just wondered how it compares with SpaceMacs in 2020 - anyone have any thou...
New
New
Exadra37
Oh just spent so much time on this to discover now that RancherOS is in end of life but Rancher is refusing to mark the Github repo as su...
New
PragmaticBookshelf
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
AstonJ
Biggest jackpot ever apparently! :upside_down_face: I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
New
DevotionGeo
I have always used antique keyboards like Cherry MX 1800 or Cherry MX 8100 and almost always have modified the switches in some way, like...
New

Sub Categories: