Initial commit, working, but w/ transparency issue

.cargo/config

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+# NOTE: For maximum performance, build using a nightly compiler
+# If you are using rust stable, remove the "-Zshare-generics=y" below.
+
+[target.x86_64-unknown-linux-gnu]
+linker = "/usr/bin/clang"
+rustflags = ["-Clink-arg=-fuse-ld=lld", "-Zshare-generics=y"]
+
+[target.x86_64-apple-darwin]
+rustflags = ["-Zshare-generics=y"]
+
+# NOTE: you must manually install lld on windows. you can easily do this with the "scoop" package manager:
+# `scoop install llvm`
+[target.x86_64-pc-windows-msvc]
+linker = "lld-link.exe"
+rustflags = ["-Clinker=lld", "-Zshare-generics=y"]

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.toml

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+[package]
+name = "bevy-nbody"
+version = "0.1.0"
+authors = ["Tyler Hallada <tyler@hallada.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+bevy = "0.1"
+bigbang = "0.0.9"
+rand = "0.7"

src/main.rs

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+use bevy::{prelude::*, render::pass::ClearColor};
+use bigbang::{Entity, GravTree};
+use rand::Rng;
+
+struct Simulation(GravTree<Entity>);
+
+fn main() {
+    let mut rng = rand::thread_rng();
+    let mut bodies = vec![];
+    for _ in 0..100 {
+        bodies.push(Entity {
+            x: rng.gen_range(-400., 400.),
+            y: rng.gen_range(-400., 400.),
+            z: 0.,
+            vx: rng.gen_range(-20., 20.),
+            vy: rng.gen_range(-20., 20.),
+            vz: 0.,
+            mass: rng.gen_range(1., 20.),
+            radius: rng.gen_range(1., 10.),
+        });
+    }
+    App::build()
+        .add_resource(Msaa { samples: 4 })
+        .add_default_plugins()
+        .add_resource(ClearColor(Color::rgb(0.1, 0.1, 0.1)))
+        .add_resource(Simulation(GravTree::new(&bodies, 0.02)))
+        .add_startup_system(add_bodies.system())
+        .add_system(time_step.system())
+        .add_system(update_bodies.system())
+        .run();
+}
+
+fn add_bodies(
+    mut commands: Commands,
+    mut materials: ResMut<Assets<ColorMaterial>>,
+    mut meshes: ResMut<Assets<Mesh>>,
+    asset_server: Res<AssetServer>,
+    grav_tree: Res<Simulation>,
+) {
+    let texture = asset_server.load("assets/circle.png").unwrap();
+    // TODO: texture transparency not working
+    commands
+        .spawn(Camera2dComponents::default())
+        .spawn(UiCameraComponents::default());
+
+    for body in grav_tree.0.as_vec() {
+        commands
+            .spawn(SpriteComponents {
+                mesh: meshes.add(Mesh::from(shape::Quad::new(Vec2::new(
+                    (body.radius / 100.) as f32,
+                    (body.radius / 100.) as f32,
+                )))),
+                material: materials.add(texture.into()),
+                translation: Translation(Vec3::new(body.x as f32, body.y as f32, body.z as f32)),
+                draw: Draw {
+                    is_transparent: true,
+                    ..Default::default()
+                },
+                ..Default::default()
+            })
+            .with(body);
+    }
+}
+
+fn time_step(mut grav_tree: ResMut<Simulation>) {
+    grav_tree.0 = grav_tree.0.time_step();
+}
+
+fn update_bodies(grav_tree: Res<Simulation>, mut body_query: Query<(&Entity, &mut Translation)>) {
+    let updated_bodies = grav_tree.0.as_vec();
+    // for body in updated_bodies.iter() {
+    //     println!("body: {}", body.as_string());
+    // }
+
+    let mut index = 0;
+    for (_, mut translation) in &mut body_query.iter() {
+        let updated_body = &updated_bodies[index];
+        translation.0.set_x(updated_body.x as f32);
+        translation.0.set_y(updated_body.y as f32);
+        translation.0.set_z(updated_body.z as f32);
+        index += 1;
+    }
+}