How can I manually create meshes in bevy with vertices?

user_15347514 0
Viewed 3743

What do I have to do to to create a mesh for bevy with the following vertices:

let mut vertices : Vec<[f32; 3]> = Vec::new();

    vertices.push([0.0, 0.0, 0.0]);
    vertices.push([1.0, 2.0, 1.0]);
    vertices.push([2.0, 0.0, 0.0]);

I then want to spawn a MeshBundle like so

commands
    .spawn(MeshBundle {
        mesh: mesh,
        transform: Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)),
        ..Default::default()
    });
bevy rust
2 Answers

Your question lacks a lot of details, for example which version of bevy you are using, which shaders you defined, etc.

I am still trying to provide an answer for bevy = 0.4 and the default shaders.

The following code demonstrates how to

  1. Define vertecies for a bevy::render::pipeline::PrimitiveTopology::TriangleList (because I suspect you are trying to do this...)
  2. Assign vertex normals to the positions
  3. Assign uv coordinates to the positions

It is heavily based on the built in shapes in bevy, which can be found here.

use bevy::prelude::*;

fn main() {
    App::build()
        .add_resource(Msaa { samples: 4 })
        .add_plugins(DefaultPlugins)
        .add_startup_system(setup.system())
        .run();
}

/// set up a simple 3D scene
fn setup(
    commands: &mut Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    let vertices = [
        ([0.0, 0.0, 0.0], [0.0, 1.0, 0.0], [1.0, 1.0]),
        ([1.0, 2.0, 1.0], [0.0, 1.0, 0.0], [1.0, 1.0]),
        ([2.0, 0.0, 0.0], [0.0, 1.0, 0.0], [1.0, 1.0]),
    ];

    let indices = bevy::render::mesh::Indices::U32(vec![0, 2, 1, 0, 3, 2]);

    let mut positions = Vec::new();
    let mut normals = Vec::new();
    let mut uvs = Vec::new();
    for (position, normal, uv) in vertices.iter() {
        positions.push(*position);
        normals.push(*normal);
        uvs.push(*uv);
    }

    let mut mesh = Mesh::new(bevy::render::pipeline::PrimitiveTopology::TriangleList);
    mesh.set_indices(Some(indices));
    mesh.set_attribute(Mesh::ATTRIBUTE_POSITION, positions);
    mesh.set_attribute(Mesh::ATTRIBUTE_NORMAL, normals);
    mesh.set_attribute(Mesh::ATTRIBUTE_UV_0, uvs);

    // add entities to the world
    commands
        // plane
        .spawn(PbrBundle {
            mesh: meshes.add(mesh),
            material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
            ..Default::default()
        })
        // light
        .spawn(LightBundle {
            transform: Transform::from_translation(Vec3::new(4.0, 8.0, 4.0)),
            ..Default::default()
        })
        // camera
        .spawn(Camera3dBundle {
            transform: Transform::from_translation(Vec3::new(-2.0, 2.5, 5.0))
                .looking_at(Vec3::default(), Vec3::unit_y()),
            ..Default::default()
        });
}

Obviously you will have to define positions, uvs and normals in such a way, that they make sense for your use case. Apart from that depending on your shader you might not need all of these Mesh attributes.

user_45934330

@frankenapps answer updated for bevy = 0.7

use bevy::prelude::*;
use bevy::render::mesh::{self, PrimitiveTopology};

fn main() {
    App::new()
        .insert_resource(Msaa { samples: 4 })
        .add_plugins(DefaultPlugins)
        .add_startup_system(setup)
        .run();
}

/// set up a simple 3D scene
fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
    ) {
    let vertices = [
        ([0.0, 0.0, 0.0], [0.0, 1.0, 0.0], [1.0, 1.0]),
        ([1.0, 2.0, 1.0], [0.0, 1.0, 0.0], [1.0, 1.0]),
        ([2.0, 0.0, 0.0], [0.0, 1.0, 0.0], [1.0, 1.0]),
    ];

    let indices = mesh::Indices::U32(vec![0, 2, 1, 0, 3, 2]);

    let mut positions = Vec::new();
    let mut normals = Vec::new();
    let mut uvs = Vec::new();
    for (position, normal, uv) in vertices.iter() {
        positions.push(*position);
        normals.push(*normal);
        uvs.push(*uv);
    }

    let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);
    mesh.set_indices(Some(indices));
    mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, positions);
    mesh.insert_attribute(Mesh::ATTRIBUTE_NORMAL, normals);
    mesh.insert_attribute(Mesh::ATTRIBUTE_UV_0, uvs);

    // add entities to the world
    // plane
    commands.spawn_bundle(PbrBundle {
        mesh: meshes.add(mesh),
        material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
        ..default()
    });
    // light
    commands.spawn_bundle(PointLightBundle {
        point_light: PointLight {
            intensity: 1500.0,
            shadows_enabled: true,
            ..default()
        },
        transform: Transform::from_xyz(4.0, 8.0, 4.0),
        ..default()
    });
    // camera
    commands.spawn_bundle(PerspectiveCameraBundle {
        transform: Transform::from_xyz(-2.0, 2.5, 5.0)
            .looking_at(Vec3::ZERO, Vec3::Y),
            ..default()
    });
}
user_98003480
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