#New to Bevy, Camera2D not showing up, not sure what I'm doing wrong

17 messages · Page 1 of 1 (latest)

hasty nebula
#

Giving Bevy a try for the first time.

https://taintedcoders.com/bevy/tutorials/pong-tutorial#creating-a-camera
Trying to follow Tainted coders Pong tutorial, running into an issue where the camera seemingly isn't being added to the project?

The tutorial describes: "Instead of a completely black window we get a lighter background." But nothing changed for me so I'm doing something wrong

I'm sure this is a very trivial fix or a typo somewhere, but I'm not sure where I'm going wrong.

Help is appreciated!

Code below:

use bevy::{math::VectorSpace, prelude::*};

#[derive(Component, Default)]
#[require(Transform)]
struct Position(Vec2);

#[derive(Component)]
#[require(Position)]
struct Ball;

const BALL_SIZE: f32 = 5.;

fn project_positions(mut positionables: Query<(&mut Transform, &Position)>) {
    for (mut transform, position) in &mut positionables {
        transform.translation = position.0.extend(0.)
    }
}

fn spawn_camera(mut commands: Commands) {
    commands.spawn_empty().insert(Camera2d); // <-- this is the line that is seemingly not working
}

fn spawn_ball(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ColorMaterial>>,
) {
    println!("spawning ball");
    let shape = Circle::new(BALL_SIZE);
    let color = Color::srgb(1., 0., 0.);
    let mesh = meshes.add(shape);
    let material = materials.add(color);
    commands
        .spawn_empty()
        .insert(Position(Vec2::ZERO))
        .insert(Ball);
}

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, (spawn_ball, spawn_camera))
        .add_systems(Update, (project_positions))
        .run();
}
image.png
Tainted Coders
Bevy Tutorial: Pong | Tainted Coders

This tutorial will teach you how to build a simple pong game using Bevy as our only dependency. We will use the simple game of pong to teach every major concept you need to create games with Bevy.

pseudo hamlet
#

I think it's because you didn't add the mesh/material to the ball

#

You've added them as assets, but you need to add them to the ball entity so that Bevy knows how to display it to the screen

#

It seems you're just missing out on this part of the tutorial:

commands.spawn((
    Ball,
    Mesh2d(mesh),
    MeshMaterial2d(material)
  ));
hasty nebula
#

thanks for the help :)

twilit pasture
#

you can spawn with a tuple with up to 16 components, and it is faster than using .insert

hasty nebula
#

so spawn_empty() makes a new entity/ new "row" in the ECS table
and .insert() gives it different components?

pseudo hamlet
#

That seems like a nice tutorial, but I don't get why they're using spawn_empty() and insert instead of just spawn yeah 🤔

#

Yeah, insert "inserts" extra components, overriding if they are already present
spawn_empty creates a new entity without giving it any components, and spawn lets you create a new entity and give it components in one go

copper quiver
#

Say that there are two archetypes (I think this is what you mean by row), one for entities with A, and one for entities with A and B. If you have an entity with component A, and then you add B, it is then moved to the archetype with both A and B

hasty nebula
#

oh okay so bevy groups entities with the same components together?

copper quiver
#

Yeah that's a good way to think about it. The underlying representation gets quite complicated...

twilit pasture
restive plover
#

I will add a note about that though, It's nicer to just use spawn, I rarely am using insert unless I'm adding to existing entities