Struct CenterOfMass

pub struct CenterOfMass(pub Vec3);

The local center of mass of an entity, representing the average position of mass in the object. Applying forces at this point produces no torque.

If CenterOfMass is not present, but the entity has a Collider, its ColliderMassProperties computed based on the shape will be used instead.

The CenterOfMass component does not take into account child entities, and it is never modified by the engine. The total center of mass of a dynamic rigid body that does consider child entities and colliders is stored in the ComputedCenterOfMass component. It is updated automatically when mass properties are changed, or when colliders are added or removed.

Usage

The CenterOfMass component can be used to define the center of mass of a rigid body entity or its descendants:

// An offset of `-0.5` along the Y axis.
commands.spawn((
    RigidBody::Dynamic,
    Collider::capsule(0.5, 1.5),
    CenterOfMass::new(0.0, -0.5, 0.0),
));

If no CenterOfMass is present, the ComputedCenterOfMass will be computed from the collider based on its shape.

// For a capsule, the center of mass is at the local origin.
commands.spawn((RigidBody::Dynamic, Collider::capsule(0.5, 1.5)));

If the rigid body has child colliders, they will contribute to the total ComputedCenterOfMass based on weighted average of their global centers of mass.

// Total center of mass: (10.0 * [0.0, -0.5, 0.0] + 5.0 * [0.0, 4.0, 0.0]) / (10.0 + 5.0) = [0.0, 1.0, 0.0]
commands.spawn((
    RigidBody::Dynamic,
    Collider::capsule(0.5, 1.5),
    Mass(10.0),
    CenterOfMass::new(0.0, -0.5, 0.0),
    Transform::default(),
))
.with_child((
    Collider::sphere(1.0),
    Mass(5.0),
    Transform::from_xyz(0.0, 4.0, 0.0),
));

To prevent the centers of mass of child entities from contributing to the total ComputedCenterOfMass, add the NoAutoCenterOfMass, component. This can be useful when full control over the center of mass is desired.

// Total center of mass: [0.0, -0.5, 0.0]
commands.spawn((
    RigidBody::Dynamic,
    Collider::capsule(0.5, 1.5),
    CenterOfMass::new(0.0, -0.5, 0.0),
    Transform::default(),
))
.with_child((
    Collider::sphere(1.0),
    Mass(5.0),
    Transform::from_xyz(0.0, 4.0, 0.0),
));

Center of Mass Updates

The CenterOfMass component is never modified by the engine, so you can safely update it at any time.

The total ComputedCenterOfMass is updated automatically whenever the mass properties of a rigid body or its descendants change, or when colliders are added, removed, or transformed. This update is triggered by adding the RecomputeMassProperties component, which is removed after the update is performed in MassPropertySystems::UpdateComputedMassProperties.

To immediately perform a manual update of the total mass properties for a specific rigid body entity, you can call MassPropertyHelper::update_mass_properties in a system.

Related Types

• ComputedCenterOfMass stores the total center of mass of a dynamic rigid body that considers child entities and colliders.
• NoAutoCenterOfMass disables the centers of mass of child entities being taken into account for the ComputedCenterOfMass.
• Mass represents resistance to linear acceleration.
• AngularInertia is the rotational equivalent of mass, representing resistance to angular acceleration.
• MassPropertiesBundle is a bundle containing mass properties.
• MassPropertyHelper is a SystemParam with utilities for computing and updating mass properties.

Tuple Fields

0: Vec3

Implementations

impl CenterOfMass

pub const ZERO: Self = _

A center of mass set at the local origin.

pub const fn new(x: f32, y: f32, z: f32) -> Self

Creates a new CenterOfMass at the given local position.

pub fn from_shape<T: ComputeMassProperties>(shape: &T) -> Self

Computes the CenterOfMass of the given shape.

// Compute the center of mass from a collider.
let center_of_mass = CenterOfMass::from_shape(&Collider::sphere(1.0));

// Bevy's primitive shapes can also be used.
let center_of_mass = CenterOfMass::from_shape(&Sphere::new(1.0));

Methods from Deref<Target = VectorF32>

pub const ZERO: Vec3 = _

pub const ONE: Vec3 = _

pub const NEG_ONE: Vec3 = _

pub const MIN: Vec3 = _

pub const MAX: Vec3 = _

pub const NAN: Vec3 = _

pub const INFINITY: Vec3 = _

pub const NEG_INFINITY: Vec3 = _

pub const X: Vec3 = _

pub const Y: Vec3 = _

pub const Z: Vec3 = _

pub const NEG_X: Vec3 = _

pub const NEG_Y: Vec3 = _

pub const NEG_Z: Vec3 = _

pub const AXES: [Vec3; 3] = _

pub fn to_array(&self) -> [f32; 3]

[x, y, z]

pub fn move_towards(&self, rhs: Vec3, d: f32) -> Vec3

Moves towards rhs based on the value d.

When d is 0.0, the result will be equal to self. When d is equal to self.distance(rhs), the result will be equal to rhs. Will not go past rhs.

pub fn any_orthogonal_vector(&self) -> Vec3

Returns some vector that is orthogonal to the given one.

The input vector must be finite and non-zero.

The output vector is not necessarily unit length. For that use Self::any_orthonormal_vector() instead.

pub fn any_orthonormal_vector(&self) -> Vec3

Returns any unit vector that is orthogonal to the given one.

The input vector must be unit length.

Panics

Will panic if self is not normalized when glam_assert is enabled.

pub fn any_orthonormal_pair(&self) -> (Vec3, Vec3)

Given a unit vector return two other vectors that together form an orthonormal basis. That is, all three vectors are orthogonal to each other and are normalized.

Panics

Will panic if self is not normalized when glam_assert is enabled.

pub fn as_dvec3(&self) -> DVec3

Casts all elements of self to f64.

pub fn as_i8vec3(&self) -> I8Vec3

Casts all elements of self to i8.

pub fn as_u8vec3(&self) -> U8Vec3

Casts all elements of self to u8.

pub fn as_i16vec3(&self) -> I16Vec3

Casts all elements of self to i16.

pub fn as_u16vec3(&self) -> U16Vec3

Casts all elements of self to u16.

pub fn as_ivec3(&self) -> IVec3

Casts all elements of self to i32.

pub fn as_uvec3(&self) -> UVec3

Casts all elements of self to u32.

pub fn as_i64vec3(&self) -> I64Vec3

Casts all elements of self to i64.

pub fn as_u64vec3(&self) -> U64Vec3

Casts all elements of self to u64.

Trait Implementations

impl Clone for CenterOfMass

fn clone(&self) -> CenterOfMass

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Component for CenterOfMass

where Self: Send + Sync + 'static,

const STORAGE_TYPE: StorageType = bevy::ecs::component::StorageType::Table

A constant indicating the storage type used for this component.

fn register_required_components( requiree: ComponentId, components: &mut Components, storages: &mut Storages, required_components: &mut RequiredComponents, inheritance_depth: u16, )

Registers required components.

fn register_component_hooks(hooks: &mut ComponentHooks)

Called when registering this component, allowing mutable access to its ComponentHooks.

impl Debug for CenterOfMass

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CenterOfMass

fn default() -> CenterOfMass

Returns the “default value” for a type.

impl Deref for CenterOfMass

type Target = Vec3

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for CenterOfMass

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl From<CenterOfMass> for ComputedCenterOfMass

fn from(center_of_mass: CenterOfMass) -> Self

Converts to this type from the input type.

impl From<ComputedCenterOfMass> for CenterOfMass

fn from(center_of_mass: ComputedCenterOfMass) -> Self

Converts to this type from the input type.

impl From<Vec3> for CenterOfMass

fn from(value: VectorF32) -> Self

Converts to this type from the input type.

impl FromReflect for CenterOfMass

where CenterOfMass: Any + Send + Sync, VectorF32: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn from_reflect(reflect: &dyn PartialReflect) -> Option<Self>

Constructs a concrete instance of Self from a reflected value.

fn take_from_reflect( reflect: Box<dyn PartialReflect>, ) -> Result<Self, Box<dyn PartialReflect>>

Attempts to downcast the given value to Self using, constructing the value using from_reflect if that fails.

impl GetTypeRegistration for CenterOfMass

where CenterOfMass: Any + Send + Sync, VectorF32: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn get_type_registration() -> TypeRegistration

Returns the default TypeRegistration for this type.

fn register_type_dependencies(registry: &mut TypeRegistry)

Registers other types needed by this type.

impl PartialEq for CenterOfMass

fn eq(&self, other: &CenterOfMass) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialReflect for CenterOfMass

where CenterOfMass: Any + Send + Sync, VectorF32: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn get_represented_type_info(&self) -> Option<&'static TypeInfo>

Returns the TypeInfo of the type represented by this value.

fn clone_value(&self) -> Box<dyn PartialReflect>

Clones the value as a Reflect trait object.

fn try_apply(&mut self, value: &dyn PartialReflect) -> Result<(), ApplyError>

Tries to apply a reflected value to this value.

fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type.

fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type.

fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type.

fn reflect_owned(self: Box<Self>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type.

fn try_into_reflect( self: Box<Self>, ) -> Result<Box<dyn Reflect>, Box<dyn PartialReflect>>

Attempts to cast this type to a boxed, fully-reflected value.

fn try_as_reflect(&self) -> Option<&dyn Reflect>

Attempts to cast this type to a fully-reflected value.

fn try_as_reflect_mut(&mut self) -> Option<&mut dyn Reflect>

Attempts to cast this type to a mutable, fully-reflected value.

fn into_partial_reflect(self: Box<Self>) -> Box<dyn PartialReflect>

Casts this type to a boxed, reflected value.

fn as_partial_reflect(&self) -> &dyn PartialReflect

Casts this type to a reflected value.

fn as_partial_reflect_mut(&mut self) -> &mut dyn PartialReflect

Casts this type to a mutable, reflected value.

fn reflect_partial_eq(&self, value: &dyn PartialReflect) -> Option<bool>

Returns a “partial equality” comparison result.

fn debug(&self, f: &mut Formatter<'_>) -> Result

Debug formatter for the value.

fn apply(&mut self, value: &(dyn PartialReflect + 'static))

Applies a reflected value to this value.

fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type).

fn serializable(&self) -> Option<Serializable<'_>>

Returns a serializable version of the value.

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl Reflect for CenterOfMass

where CenterOfMass: Any + Send + Sync, VectorF32: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn into_any(self: Box<Self>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &dyn Any

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut dyn Any

Returns the value as a &mut dyn Any.

fn into_reflect(self: Box<Self>) -> Box<dyn Reflect>

Casts this type to a boxed, fully-reflected value.

fn as_reflect(&self) -> &dyn Reflect

Casts this type to a fully-reflected value.

fn as_reflect_mut(&mut self) -> &mut dyn Reflect

Casts this type to a mutable, fully-reflected value.

fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value.

impl TupleStruct for CenterOfMass

where CenterOfMass: Any + Send + Sync, VectorF32: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn field(&self, index: usize) -> Option<&dyn PartialReflect>

Returns a reference to the value of the field with index index as a &dyn Reflect.

fn field_mut(&mut self, index: usize) -> Option<&mut dyn PartialReflect>

Returns a mutable reference to the value of the field with index index as a &mut dyn Reflect.

fn field_len(&self) -> usize

Returns the number of fields in the tuple struct.

fn iter_fields(&self) -> TupleStructFieldIter<'_>

Returns an iterator over the values of the tuple struct’s fields.

fn clone_dynamic(&self) -> DynamicTupleStruct

Clones the struct into a DynamicTupleStruct.

fn get_represented_tuple_struct_info(&self) -> Option<&'static TupleStructInfo>

Will return None if TypeInfo is not available.

impl TypePath for CenterOfMass

where CenterOfMass: Any + Send + Sync,

fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type.

fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous.

fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous.

fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous.

impl Typed for CenterOfMass

where CenterOfMass: Any + Send + Sync, VectorF32: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.

impl Copy for CenterOfMass

impl StructuralPartialEq for CenterOfMass