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boids-rs
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move boid_mesh code

main
Zynh Ludwig 2024-09-01 14:24:22 -07:00
parent e41ff1cf61
commit d9a8896444
2 changed files with 76 additions and 73 deletions
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71
src/boid_mesh.rs Normal file
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@ -0,0 +1,71 @@
use bevy::{
prelude::*,
render::{
mesh::{Indices, PrimitiveTopology},
render_asset::RenderAssetUsages,
},
sprite::Mesh2dHandle,
};
use std::f32::consts::FRAC_PI_2;
#[derive(Resource, Default)]
pub struct BoidMesh(pub Mesh2dHandle);
pub fn build_boid_mesh(mut meshes: ResMut<Assets<Mesh>>, mut boid_mesh: ResMut<BoidMesh>) {
let mesh = Mesh2dHandle(meshes.add(make_boid_mesh()));
boid_mesh.0 = mesh;
}
pub fn make_boid_mesh() -> Mesh {
const TRIANGLE_HEIGHT: f32 = 10.;
const TRIANGLE_WIDTH: f32 = 5.;
const STROKE_WIDTH: f32 = 0.25;
const HALF_HEIGHT: f32 = TRIANGLE_HEIGHT / 2.0;
const HALF_WIDTH: f32 = TRIANGLE_WIDTH / 2.0;
let w2 = (HALF_WIDTH * HALF_WIDTH + TRIANGLE_HEIGHT * TRIANGLE_HEIGHT).sqrt();
let c = STROKE_WIDTH / (HALF_WIDTH / w2);
let alpha: f32 = (TRIANGLE_HEIGHT / HALF_WIDTH).atan();
let b: f32 = STROKE_WIDTH * (FRAC_PI_2 - (alpha / 2.)).tan();
let mut boid_mesh = Mesh::new(
PrimitiveTopology::TriangleList,
RenderAssetUsages::RENDER_WORLD,
);
#[rustfmt::skip]
let verts = vec![
[0.0, HALF_HEIGHT - c, 0.0],
[0.0, HALF_HEIGHT, 0.0],
[
HALF_WIDTH - b,
-HALF_HEIGHT + STROKE_WIDTH,
0.0,
],
[HALF_WIDTH, -HALF_HEIGHT, 0.0],
[
-HALF_WIDTH + b,
-HALF_HEIGHT + STROKE_WIDTH,
0.0,
],
[-HALF_WIDTH, -HALF_HEIGHT, 0.0],
];
boid_mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, verts);
#[rustfmt::skip]
let indices = vec![
0, 1, 5,
0, 2, 1,
1, 2, 3,
0, 5, 4,
3, 4, 5,
2, 4, 3
];
boid_mesh.insert_indices(Indices::U32(indices));
boid_mesh
}

78
src/main.rs
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@ -1,26 +1,17 @@
use bevy::{
color::palettes::tailwind,
prelude::*,
render::{
mesh::{Indices, PrimitiveTopology},
render_asset::RenderAssetUsages,
},
sprite::{MaterialMesh2dBundle, Mesh2dHandle},
};
use std::f32::consts::FRAC_PI_2;
mod boid_mesh;
use bevy::{color::palettes::tailwind, prelude::*, sprite::MaterialMesh2dBundle};
use boid_mesh::BoidMesh;
fn main() {
App::new()
.init_resource::<BoidMesh>()
.add_plugins(DefaultPlugins)
.add_systems(Startup, (build_boid_mesh, setup).chain())
.add_systems(Startup, (boid_mesh::build_boid_mesh, setup).chain())
.add_systems(Update, move_boids)
.run();
}
#[derive(Resource, Default)]
struct BoidMesh(Mesh2dHandle);
#[derive(Component, Default)]
struct Boid;
@ -40,11 +31,6 @@ fn move_boids(mut boids: Query<(&mut Transform, &Velocity), With<Boid>>) {
});
}
fn build_boid_mesh(mut meshes: ResMut<Assets<Mesh>>, mut boid_mesh: ResMut<BoidMesh>) {
let mesh = Mesh2dHandle(meshes.add(make_boid_mesh()));
boid_mesh.0 = mesh;
}
fn setup(
mut commands: Commands,
mut materials: ResMut<Assets<ColorMaterial>>,
@ -65,57 +51,3 @@ fn setup(
..default()
});
}
fn make_boid_mesh() -> Mesh {
const TRIANGLE_HEIGHT: f32 = 10.;
const TRIANGLE_WIDTH: f32 = 5.;
const STROKE_WIDTH: f32 = 0.25;
const HALF_HEIGHT: f32 = TRIANGLE_HEIGHT / 2.0;
const HALF_WIDTH: f32 = TRIANGLE_WIDTH / 2.0;
let w2 = (HALF_WIDTH * HALF_WIDTH + TRIANGLE_HEIGHT * TRIANGLE_HEIGHT).sqrt();
let c = STROKE_WIDTH / (HALF_WIDTH / w2);
let alpha: f32 = (TRIANGLE_HEIGHT / HALF_WIDTH).atan();
let b: f32 = STROKE_WIDTH * (FRAC_PI_2 - (alpha / 2.)).tan();
let mut boid_mesh = Mesh::new(
PrimitiveTopology::TriangleList,
RenderAssetUsages::RENDER_WORLD,
);
#[rustfmt::skip]
let verts = vec![
[0.0, HALF_HEIGHT - c, 0.0],
[0.0, HALF_HEIGHT, 0.0],
[
HALF_WIDTH - b,
-HALF_HEIGHT + STROKE_WIDTH,
0.0,
],
[HALF_WIDTH, -HALF_HEIGHT, 0.0],
[
-HALF_WIDTH + b,
-HALF_HEIGHT + STROKE_WIDTH,
0.0,
],
[-HALF_WIDTH, -HALF_HEIGHT, 0.0],
];
boid_mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, verts);
#[rustfmt::skip]
let indices = vec![
0, 1, 5,
0, 2, 1,
1, 2, 3,
0, 5, 4,
3, 4, 5,
2, 4, 3
];
boid_mesh.insert_indices(Indices::U32(indices));
boid_mesh
}