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
johnp
Hi Brian, Looks like the api for tinydb has changed a little. Noticed while working on chapter 7 that the .purge() call to the db throws...
New
cro
I am working on the “Your Turn” for chapter one and building out the restart button talked about on page 27. It recommends looking into ...
New
adamwoolhether
I’m not quite sure what’s going on here, but I’m unable to have to containers successfully complete the Readiness/Liveness checks. I’m im...
New
brunogirin
When trying to run tox in parallel as explained on page 151, I got the following error: tox: error: argument -p/–parallel: expected one...
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
redconfetti
Docker-Machine became part of the Docker Toolbox, which was deprecated in 2020, long after Docker Desktop supported Docker Engine nativel...
New
mcpierce
@mfazio23 I’ve applied the changes from Chapter 5 of the book and everything builds correctly and runs. But, when I try to start a game,...
New
SlowburnAZ
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
New
dachristenson
@mfazio23 Android Studio will not accept anything I do when trying to use the Transformations class, as described on pp. 140-141. Googl...
New

Other popular topics Top

Devtalk
Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...
1032 17402 381
New
AstonJ
What chair do you have while working… and why? Is there a ‘best’ type of chair or working position for developers?
New
dasdom
No chair. I have a standing desk. This post was split into a dedicated thread from our thread about chairs :slight_smile:
New
DevotionGeo
I know that -t flag is used along with -i flag for getting an interactive shell. But I cannot digest what the man page for docker run com...
New
New
AstonJ
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first: asdf plugin-upd...
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
New
PragmaticBookshelf
Author Spotlight Jamis Buck @jamis This month, we have the pleasure of spotlighting author Jamis Buck, who has written Mazes for Prog...
New
sir.laksmana_wenk
I’m able to do the “artistic” part of game-development; character designing/modeling, music, environment modeling, etc. However, I don’t...
New

Sub Categories: