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// Port of box2d-cpp-reference/include/box2d/id.h
//
// These ids are opaque handles to internal Box2D objects, passed by value. All
// ids are null when zero-initialized. The store/load helpers pack and unpack a
// handle into a plain integer; the bit layout is reproduced exactly so handles
// round-trip identically to the C library.
//
// SPDX-FileCopyrightText: 2023 Erin Catto
// SPDX-License-Identifier: MIT
/// World id references a world instance. Treat as an opaque handle.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub struct WorldId {
pub index1: u16,
pub generation: u16,
}
/// Body id references a body instance. Treat as an opaque handle.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub struct BodyId {
pub index1: i32,
pub world0: u16,
pub generation: u16,
}
/// Shape id references a shape instance. Treat as an opaque handle.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub struct ShapeId {
pub index1: i32,
pub world0: u16,
pub generation: u16,
}
/// Chain id references a chain instance. Treat as an opaque handle.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub struct ChainId {
pub index1: i32,
pub world0: u16,
pub generation: u16,
}
/// Joint id references a joint instance. Treat as an opaque handle.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub struct JointId {
pub index1: i32,
pub world0: u16,
pub generation: u16,
}
/// Contact id references a contact instance. Treat as an opaque handle.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub struct ContactId {
pub index1: i32,
pub world0: u16,
pub padding: i16,
pub generation: u32,
}
impl WorldId {
/// Store a world id into a u32. (b2StoreWorldId)
pub fn store(self) -> u32 {
((self.index1 as u32) << 16) | (self.generation as u32)
}
/// Load a u32 into a world id. (b2LoadWorldId)
pub fn load(x: u32) -> WorldId {
WorldId {
index1: (x >> 16) as u16,
generation: x as u16,
}
}
/// True if this id is null (index1 == 0). (B2_IS_NULL)
pub fn is_null(self) -> bool {
self.index1 == 0
}
/// True if this id is non-null. (B2_IS_NON_NULL)
pub fn is_non_null(self) -> bool {
self.index1 != 0
}
}
// Body, shape, chain, and joint ids share the same 64-bit layout, so a macro
// generates their identical store/load/null helpers.
macro_rules! impl_u64_id {
($ty:ident) => {
impl $ty {
/// Store this id into a u64.
pub fn store(self) -> u64 {
((self.index1 as u64) << 32)
| ((self.world0 as u64) << 16)
| (self.generation as u64)
}
/// Load a u64 into this id type.
pub fn load(x: u64) -> $ty {
$ty {
index1: (x >> 32) as i32,
world0: (x >> 16) as u16,
generation: x as u16,
}
}
/// True if this id is null (index1 == 0). (B2_IS_NULL)
pub fn is_null(self) -> bool {
self.index1 == 0
}
/// True if this id is non-null. (B2_IS_NON_NULL)
pub fn is_non_null(self) -> bool {
self.index1 != 0
}
}
};
}
impl_u64_id!(BodyId);
impl_u64_id!(ShapeId);
impl_u64_id!(ChainId);
impl_u64_id!(JointId);
impl ContactId {
/// Store a contact id into three u32 values. (b2StoreContactId)
pub fn store(self) -> [u32; 3] {
[self.index1 as u32, self.world0 as u32, self.generation]
}
/// Load three u32 values into a contact id. (b2LoadContactId)
pub fn load(values: [u32; 3]) -> ContactId {
ContactId {
index1: values[0] as i32,
world0: values[1] as u16,
padding: 0,
generation: values[2],
}
}
/// True if this id is null (index1 == 0). (B2_IS_NULL)
pub fn is_null(self) -> bool {
self.index1 == 0
}
/// True if this id is non-null. (B2_IS_NON_NULL)
pub fn is_non_null(self) -> bool {
self.index1 != 0
}
}