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use std::ops::Mul;
use super::Transform;
#[cfg(feature = "bevy-support")]
use bevy_ecs::{component::Component, reflect::ReflectComponent};
use bevy_math::{Affine3A, Dir3, Mat4, Quat, Vec3, Vec3A};
#[cfg(feature = "bevy-support")]
use bevy_reflect::{std_traits::ReflectDefault, Reflect};
/// Describe the position of an entity relative to the reference frame.
///
/// * To place or move an entity, you should set its [`Transform`].
/// * [`GlobalTransform`] is fully managed by bevy, you cannot mutate it, use
/// [`Transform`] instead.
/// * To get the global transform of an entity, you should get its [`GlobalTransform`].
/// * For transform hierarchies to work correctly, you must have both a [`Transform`] and a [`GlobalTransform`].
/// * You may use the [`TransformBundle`](crate::TransformBundle) to guarantee this.
///
/// ## [`Transform`] and [`GlobalTransform`]
///
/// [`Transform`] is the position of an entity relative to its parent position, or the reference
/// frame if it doesn't have a [`Parent`](bevy_hierarchy::Parent).
///
/// [`GlobalTransform`] is the position of an entity relative to the reference frame.
///
/// [`GlobalTransform`] is updated from [`Transform`] by systems in the system set
/// [`TransformPropagate`](crate::TransformSystem::TransformPropagate).
///
/// This system runs during [`PostUpdate`](bevy_app::PostUpdate). If you
/// update the [`Transform`] of an entity in this schedule or after, you will notice a 1 frame lag
/// before the [`GlobalTransform`] is updated.
///
/// # Examples
///
/// - [`transform`][transform_example]
///
/// [transform_example]: https://github.com/bevyengine/bevy/blob/latest/examples/transforms/transform.rs
#[derive(Debug, PartialEq, Clone, Copy)]
#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(
feature = "bevy-support",
derive(Component, Reflect),
reflect(Component, Default, PartialEq)
)]
pub struct GlobalTransform(Affine3A);
macro_rules! impl_local_axis {
($pos_name: ident, $neg_name: ident, $axis: ident) => {
#[doc=std::concat!("Return the local ", std::stringify!($pos_name), " vector (", std::stringify!($axis) ,").")]
#[inline]
pub fn $pos_name(&self) -> Dir3 {
Dir3::new_unchecked((self.0.matrix3 * Vec3::$axis).normalize())
}
#[doc=std::concat!("Return the local ", std::stringify!($neg_name), " vector (-", std::stringify!($axis) ,").")]
#[inline]
pub fn $neg_name(&self) -> Dir3 {
-self.$pos_name()
}
};
}
impl GlobalTransform {
/// An identity [`GlobalTransform`] that maps all points in space to themselves.
pub const IDENTITY: Self = Self(Affine3A::IDENTITY);
#[doc(hidden)]
#[inline]
pub fn from_xyz(x: f32, y: f32, z: f32) -> Self {
Self::from_translation(Vec3::new(x, y, z))
}
#[doc(hidden)]
#[inline]
pub fn from_translation(translation: Vec3) -> Self {
GlobalTransform(Affine3A::from_translation(translation))
}
#[doc(hidden)]
#[inline]
pub fn from_rotation(rotation: Quat) -> Self {
GlobalTransform(Affine3A::from_rotation_translation(rotation, Vec3::ZERO))
}
#[doc(hidden)]
#[inline]
pub fn from_scale(scale: Vec3) -> Self {
GlobalTransform(Affine3A::from_scale(scale))
}
/// Returns the 3d affine transformation matrix as a [`Mat4`].
#[inline]
pub fn compute_matrix(&self) -> Mat4 {
Mat4::from(self.0)
}
/// Returns the 3d affine transformation matrix as an [`Affine3A`].
#[inline]
pub fn affine(&self) -> Affine3A {
self.0
}
/// Returns the transformation as a [`Transform`].
///
/// The transform is expected to be non-degenerate and without shearing, or the output
/// will be invalid.
#[inline]
pub fn compute_transform(&self) -> Transform {
let (scale, rotation, translation) = self.0.to_scale_rotation_translation();
Transform {
translation,
rotation,
scale,
}
}
/// Returns the [`Transform`] `self` would have if it was a child of an entity
/// with the `parent` [`GlobalTransform`].
///
/// This is useful if you want to "reparent" an [`Entity`](bevy_ecs::entity::Entity).
/// Say you have an entity `e1` that you want to turn into a child of `e2`,
/// but you want `e1` to keep the same global transform, even after re-parenting. You would use:
///
/// ```
/// # use bevy_transform::prelude::{GlobalTransform, Transform};
/// # use bevy_ecs::prelude::{Entity, Query, Component, Commands};
/// # use bevy_hierarchy::{prelude::Parent, BuildChildren};
/// #[derive(Component)]
/// struct ToReparent {
/// new_parent: Entity,
/// }
/// fn reparent_system(
/// mut commands: Commands,
/// mut targets: Query<(&mut Transform, Entity, &GlobalTransform, &ToReparent)>,
/// transforms: Query<&GlobalTransform>,
/// ) {
/// for (mut transform, entity, initial, to_reparent) in targets.iter_mut() {
/// if let Ok(parent_transform) = transforms.get(to_reparent.new_parent) {
/// *transform = initial.reparented_to(parent_transform);
/// commands.entity(entity)
/// .remove::<ToReparent>()
/// .set_parent(to_reparent.new_parent);
/// }
/// }
/// }
/// ```
///
/// The transform is expected to be non-degenerate and without shearing, or the output
/// will be invalid.
#[inline]
pub fn reparented_to(&self, parent: &GlobalTransform) -> Transform {
let relative_affine = parent.affine().inverse() * self.affine();
let (scale, rotation, translation) = relative_affine.to_scale_rotation_translation();
Transform {
translation,
rotation,
scale,
}
}
/// Extracts `scale`, `rotation` and `translation` from `self`.
///
/// The transform is expected to be non-degenerate and without shearing, or the output
/// will be invalid.
#[inline]
pub fn to_scale_rotation_translation(&self) -> (Vec3, Quat, Vec3) {
self.0.to_scale_rotation_translation()
}
impl_local_axis!(right, left, X);
impl_local_axis!(up, down, Y);
impl_local_axis!(back, forward, Z);
/// Get the translation as a [`Vec3`].
#[inline]
pub fn translation(&self) -> Vec3 {
self.0.translation.into()
}
/// Get the translation as a [`Vec3A`].
#[inline]
pub fn translation_vec3a(&self) -> Vec3A {
self.0.translation
}
/// Get an upper bound of the radius from the given `extents`.
#[inline]
pub fn radius_vec3a(&self, extents: Vec3A) -> f32 {
(self.0.matrix3 * extents).length()
}
/// Transforms the given `point`, applying shear, scale, rotation and translation.
///
/// This moves `point` into the local space of this [`GlobalTransform`].
#[inline]
pub fn transform_point(&self, point: Vec3) -> Vec3 {
self.0.transform_point3(point)
}
/// Multiplies `self` with `transform` component by component, returning the
/// resulting [`GlobalTransform`]
#[inline]
pub fn mul_transform(&self, transform: Transform) -> Self {
Self(self.0 * transform.compute_affine())
}
}
impl Default for GlobalTransform {
fn default() -> Self {
Self::IDENTITY
}
}
impl From<Transform> for GlobalTransform {
fn from(transform: Transform) -> Self {
Self(transform.compute_affine())
}
}
impl From<Affine3A> for GlobalTransform {
fn from(affine: Affine3A) -> Self {
Self(affine)
}
}
impl From<Mat4> for GlobalTransform {
fn from(world_from_local: Mat4) -> Self {
Self(Affine3A::from_mat4(world_from_local))
}
}
impl Mul<GlobalTransform> for GlobalTransform {
type Output = GlobalTransform;
#[inline]
fn mul(self, global_transform: GlobalTransform) -> Self::Output {
GlobalTransform(self.0 * global_transform.0)
}
}
impl Mul<Transform> for GlobalTransform {
type Output = GlobalTransform;
#[inline]
fn mul(self, transform: Transform) -> Self::Output {
self.mul_transform(transform)
}
}
impl Mul<Vec3> for GlobalTransform {
type Output = Vec3;
#[inline]
fn mul(self, value: Vec3) -> Self::Output {
self.transform_point(value)
}
}
#[cfg(test)]
mod test {
use super::*;
use bevy_math::EulerRot::XYZ;
fn transform_equal(left: GlobalTransform, right: Transform) -> bool {
left.0.abs_diff_eq(right.compute_affine(), 0.01)
}
#[test]
fn reparented_to_transform_identity() {
fn reparent_to_same(t1: GlobalTransform, t2: GlobalTransform) -> Transform {
t2.mul_transform(t1.into()).reparented_to(&t2)
}
let t1 = GlobalTransform::from(Transform {
translation: Vec3::new(1034.0, 34.0, -1324.34),
rotation: Quat::from_euler(XYZ, 1.0, 0.9, 2.1),
scale: Vec3::new(1.0, 1.0, 1.0),
});
let t2 = GlobalTransform::from(Transform {
translation: Vec3::new(0.0, -54.493, 324.34),
rotation: Quat::from_euler(XYZ, 1.9, 0.3, 3.0),
scale: Vec3::new(1.345, 1.345, 1.345),
});
let retransformed = reparent_to_same(t1, t2);
assert!(
transform_equal(t1, retransformed),
"t1:{:#?} retransformed:{:#?}",
t1.compute_transform(),
retransformed,
);
}
#[test]
fn reparented_usecase() {
let t1 = GlobalTransform::from(Transform {
translation: Vec3::new(1034.0, 34.0, -1324.34),
rotation: Quat::from_euler(XYZ, 0.8, 1.9, 2.1),
scale: Vec3::new(10.9, 10.9, 10.9),
});
let t2 = GlobalTransform::from(Transform {
translation: Vec3::new(28.0, -54.493, 324.34),
rotation: Quat::from_euler(XYZ, 0.0, 3.1, 0.1),
scale: Vec3::new(0.9, 0.9, 0.9),
});
// goal: find `X` such as `t2 * X = t1`
let reparented = t1.reparented_to(&t2);
let t1_prime = t2 * reparented;
assert!(
transform_equal(t1, t1_prime.into()),
"t1:{:#?} t1_prime:{:#?}",
t1.compute_transform(),
t1_prime.compute_transform(),
);
}
}