add an example for creating convex shapes

examples/test_convex_shapes.rs

@@ -0,0 +1,156 @@
+mod common;
+
+use bevy::prelude::*;
+use bevy::render::mesh::Indices;
+use bevy::render::render_resource::PrimitiveTopology;
+use bevy_mod_physx::assets::GeometryInner;
+use bevy_mod_physx::physx_extras::ConvexMeshExtras;
+use bevy_mod_physx::prelude::{self as bpx, *};
+
+fn main() {
+ App::new()
+ .add_plugins(DefaultPlugins)
+ .add_plugins(PhysicsPlugins)
+ .add_plugins(common::DemoUtils) // optional
+ .add_systems(Startup, (
+ spawn_scene,
+ spawn_camera_and_light,
+ ))
+ .run();
+}
+
+// generates bevy mesh from physx convex mesh
+fn create_bevy_mesh_from_geometry(geometry: &Geometry) -> Mesh {
+ let mut positions = vec![];
+ let mut indices = vec![];
+ let mut normals = vec![];
+
+ match &geometry.obj {
+ GeometryInner::ConvexMesh { mesh, scale, .. } => {
+ let mesh = mesh.lock().unwrap();
+
+ let mut vertices = vec![];
+ // arbitrary axis rotation not implemented
+ assert_eq!(scale.rotation.to_bevy(), Quat::IDENTITY);
+ for vertex in mesh.get_vertices() {
+ vertices.push(vertex.to_bevy() * scale.scale.to_bevy());
+ }
+
+ let index_buffer = mesh.get_index_buffer();
+ for idx in 0..mesh.get_nb_polygons() {
+ let polygon = mesh.get_polygon_data(idx).unwrap();
+ for i in polygon.index_base+1..polygon.index_base+polygon.nb_verts-1 {
+ let a = vertices[index_buffer[polygon.index_base as usize] as usize];
+ let b = vertices[index_buffer[i as usize] as usize];
+ let c = vertices[index_buffer[i as usize + 1] as usize];
+
+ indices.push(indices.len() as u32);
+ indices.push(indices.len() as u32);
+ indices.push(indices.len() as u32);
+
+ positions.push(a);
+ positions.push(b);
+ positions.push(c);
+
+ let normal = (b - a).cross(c - a).normalize();
+ normals.push(normal);
+ normals.push(normal);
+ normals.push(normal);
+ }
+ }
+ },
+
+ // see https://github.com/rlidwka/bevy_mod_physx/blob/2cfc2e55db7509fa881c3687800472fa73310361/src/render.rs
+ // for inspiration how to implement other shapes
+ _ => unimplemented!()
+ }
+
+ let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);
+ mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, positions);
+ mesh.insert_attribute(Mesh::ATTRIBUTE_NORMAL, normals);
+ mesh.set_indices(Some(Indices::U32(indices)));
+ mesh
+}
+
+pub fn spawn_scene(
+ mut commands: Commands,
+ mut meshes: ResMut<Assets<Mesh>>,
+ mut materials: ResMut<Assets<StandardMaterial>>,
+ mut physics: ResMut<Physics>,
+ mut px_geometries: ResMut<Assets<bpx::Geometry>>,
+) {
+ // plane
+ commands.spawn((
+ RigidBody::Static,
+ bpx::Shape {
+ geometry: px_geometries.add(bpx::Geometry::halfspace(Vec3::Y)),
+ ..default()
+ },
+ PbrBundle {
+ mesh: meshes.add(shape::Plane::from_size(1000.0).into()),
+ material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
+ ..default()
+ }
+ ));
+
+ // cylinder (it's a helper for convex shape, physx doesn't have native cylinders)
+ let geometry = bpx::Geometry::cylinder(&mut physics, 0.5, 0.5, 10).unwrap();
+ let mesh = create_bevy_mesh_from_geometry(&geometry);
+ commands.spawn((
+ PbrBundle {
+ mesh: meshes.add(mesh),
+ material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
+ transform: Transform::from_xyz(-2.0, 7.0, 0.0).with_rotation(Quat::from_rotation_z(-1.)),
+ ..default()
+ },
+ RigidBody::Dynamic,
+ bpx::Shape {
+ geometry: px_geometries.add(geometry),
+ ..default()
+ },
+ ));
+
+ // arbitrary convex shape
+ let vertices = vec![
+ Vec3::new(0., 1., 0.),
+ Vec3::new(0., -1., 0.),
+ Vec3::new(1., 0., 0.),
+ Vec3::new(-1., 0., 0.),
+ Vec3::new(0., 0., 1.),
+ Vec3::new(0., 0., -1.),
+ ];
+
+ let geometry = bpx::Geometry::convex_mesh(&mut physics, &vertices).unwrap()
+ .with_scale(Vec3::splat(0.8), Quat::IDENTITY);
+ let mesh = create_bevy_mesh_from_geometry(&geometry);
+ commands.spawn((
+ PbrBundle {
+ mesh: meshes.add(mesh),
+ material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
+ transform: Transform::from_xyz(2.0, 7.0, 0.0).with_rotation(Quat::from_rotation_z(-1.)),
+ ..default()
+ },
+ RigidBody::Dynamic,
+ bpx::Shape {
+ geometry: px_geometries.add(geometry),
+ ..default()
+ },
+ ));
+}
+
+fn spawn_camera_and_light(mut commands: Commands) {
+ commands
+ .spawn(SpatialBundle::from_transform(Transform::from_xyz(0., 2.5, 0.)))
+ .with_children(|builder| {
+ builder.spawn(Camera3dBundle {
+ transform: Transform::from_xyz(0.0, 2.5, 10.0).looking_at(Vec3::ZERO, Vec3::Y),
+ ..default()
+ });
+ })
+ .insert(Name::new("Camera"));
+
+ commands.spawn(DirectionalLightBundle {
+ transform: Transform::from_rotation(Quat::from_rotation_x(-std::f32::consts::FRAC_PI_4)),
+ ..default()
+ }).insert(Name::new("Light"));
+}