Odin/vendor/box2d/id.odin

package vendor_box2d

/**
 * @defgroup id Ids
 * These ids serve as handles to internal Box2D objects.
 * These should be considered opaque data and passed by value.
 * Include this header if you need the id types and not the whole Box2D API.
 * All ids are considered null if initialized to zero.
 *
 * For example in C++:
 *
 * @code{.cxx}
 * b2WorldId worldId = {};
 * @endcode
 *
 * Or in C:
 *
 * @code{.c}
 * b2WorldId worldId = {0};
 * @endcode
 *
 * These are both considered null.
 *
 * @warning Do not use the internals of these ids. They are subject to change. Ids should be treated as opaque objects.
 * @warning You should use ids to access objects in Box2D. Do not access files within the src folder. Such usage is unsupported.
 */

/// World id references a world instance. This should be treated as an opaque handle.
WorldId :: struct {
	index1:   u16,
	revision: u16,
}

/// Body id references a body instance. This should be treated as an opaque handle.
BodyId :: struct {
	index1:   i32,
	world0:   u16,
	revision: u16,
}

/// Shape id references a shape instance. This should be treated as an opaque handle.
ShapeId :: struct {
	index1:   i32,
	world0:   u16,
	revision: u16,
}

/// Joint id references a joint instance. This should be treated as an opaque handle.
JointId :: struct {
	index1:   i32,
	world0:   u16,
	revision: u16,
}

/// Chain id references a chain instances. This should be treated as an opaque handle.
ChainId :: struct {
	index1:   i32,
	world0:   u16,
	revision: u16,
}

/// Use these to make your identifiers null.
/// You may also use zero initialization to get null.
nullWorldId :: WorldId{}
nullBodyId  :: BodyId{}
nullShapeId :: ShapeId{}
nullJointId :: JointId{}
nullChainId :: ChainId{}

/// Macro to determine if any id is null.
IS_NULL :: proc "c" (id: $T) -> bool { return id.index1 == 0 }

/// Macro to determine if any id is non-null.
IS_NON_NULL :: proc "c" (id: $T) -> bool { return id.index1 != 0 }

/// Compare two ids for equality. Doesn't work for b2WorldId.
ID_EQUALS :: proc "c" (id1, id2: $T) -> bool { return id1.index1 == id2.index1 && id1.world0 == id2.world0 && id1.revision == id2.revision }