HE3D physics — rigid-body dynamics for interactive applications. HE3D 物理 —— 面向交互式应用的刚体动力学。

The crate owns its Bodies through a [BodyId] and knows nothing about rendering: it never sees an ObjectId, a Scene, or a Transform. A Body's placement is a position and an orientation, and the application owns both the link between a Body and whatever draws it and the per-frame copy of that placement. See docs/adr/0001. 本 crate 通过 [BodyId] 拥有自己的 Body，且对渲染一无所知：它永远看不到 ObjectId、Scene 或 Transform。Body 的摆放是位置与朝向；Body 与"画它的东西" 之间的联系、以及每帧复制该摆放的动作，都由应用拥有。见 docs/adr/0001。

Bodies come in three motion modes; the one that needs care is [MotionType::Kinematic], driven by a velocity the application sets and changeable by no Contact. See [MotionType]. Body 有三种运动模式；其中需要留意的是 [MotionType::Kinematic]：它由应用设定的速度驱动，且没有任何 Contact 能改变它。见 [MotionType]。

Example

示例

use he3d_math::Vec3;
use he3d_physics::{BodyDesc, ContactPhase, Shape, World};

let mut world = World::new();

// Static scenery is just a Body that never moves.
// 静态景物就是一个永不移动的 Body。
world.add_body(
   BodyDesc::stationary(Shape::cuboid(Vec3::new(10.0, 0.5, 10.0))).at(Vec3::ZERO),
);
let ball = world.add_body(
   BodyDesc::dynamic(Shape::sphere(0.5), 1.0)
      .at(Vec3::new(0.0, 8.0, 0.0))
      .with_friction(0.45)
      .with_restitution(0.3),
);

// A fixed step; the caller owns the accumulator and the per-frame step cap.
// 固定步长；累加器与每帧步数上限由调用方拥有。
//
// Each step publishes the Contacts it found. Asking that list is the *only* thing
// needed to know whether the ball has touched down: no geometry, no tolerances.
// 每一步都会发布它找到的 Contact。问这个列表就是判断球是否触地所需的**全部**手段：
// 无需几何，无需容差。
let mut touched_down = false;
for _ in 0..240 {
   world.step(1.0 / 120.0);
   touched_down |= world
      .contacts()
      .iter()
      .any(|contact| contact.involves(ball) && contact.phase != ContactPhase::End);
}
assert!(touched_down, "the ball must reach the floor on the way down");

// Let it finish bouncing and settle.
// 让它弹完并稳定下来。
for _ in 0..600 {
   world.step(1.0 / 120.0);
}
let resting = world.position(ball).expect("the ball exists");
assert!((resting.y - 1.0).abs() < 0.05, "resting at {resting:?} instead");

// One thing to know before relying on `contacts()`: a Body that has gone to sleep
// stops producing constraints, so its Contacts disappear with it. Ask while the
// Body is awake, or wake it first with [`World::wake`].
// 依赖 `contacts()` 之前要知道一件事：睡着的 Body 不再产生约束，因此它的 Contact 会随
// 之消失。请在 Body 清醒时询问，或先用 [`World::wake`] 唤醒它。
assert!(!world.is_empty());

he3d-physics 0.3.0

Example