A system for maintaining local affine transforms layered on a hierarchy. More...

#include <transform_hierarchy.h>

Public Types
using	xfn = AffineTransform< T, N >

using	LT = LocalTransform< HTag, T, N, XTag >

Public Member Functions
	TransformSystem (entt::registry &reg, HierarchySystem< HTag > &hierarchy)

	TransformSystem (const TransformSystem &)=delete

TransformSystem &	operator= (const TransformSystem &)=delete

HierarchySystem< HTag > &	hierarchy ()

const HierarchySystem< HTag > &	hierarchy () const

void	set_transform (entt::entity eid, xfn xf)
	Set the local (child-to-parent) transform for an entity.

std::optional< xfn >	get_transform (entt::entity eid) const
	Get the local transform for an entity, or `std::nullopt` if none is set.

std::optional< LT >	remove_transform (entt::entity eid)
	Remove the local transform for an entity. Returns the old component if it existed.

xfn	object_to_world (entt::entity node) const
	Compute the cumulative transform that positions `node` in the space of the root.

xfn	xf_between (entt::entity from_node, entt::entity to_node) const
	Compute the transform from `from_node`'s space to `to_node`'s space.

auto	traverse (entt::entity root, SiblingOrder order) const
	Create a traversal which yields `TransformedNode<NodeEntry,T,N>`.

template<AnyTraversalConcept Traversal, typename GetId >
auto	augment_with_transforms (Traversal &&t, GetId &&get_id) const
	Convert a traversal of `Node` to a traversal of `TransformedNode<Node,T,N>`.

Public Attributes
entt::sigh< void(entt::entity, xfn)>	on_transform_set
	Emitted when a transform is first set on an entity. Args: (entity, new_xf).

entt::sigh< void(entt::entity, xfn)>	on_transform_removed
	Emitted when a transform is removed from an entity. Args: (entity, old_xf).

entt::sigh< void(entt::entity, xfn, xfn)>	on_transform_changed
	Emitted when an existing transform changes. Args: (entity, old_xf, new_xf).

Detailed Description

template<typename HTag, typename T = double, size_t N = 2, typename XTag = HTag>
struct entttree::TransformSystem< HTag, T, N, XTag >

A system for maintaining local affine transforms layered on a hierarchy.

Each entity may optionally have a LocalTransform component representing the transform from the entity's local space to its parent's space. Entities without an explicit transform are assumed to have the identity.

Emits typed signals when transforms are set, changed, or removed.

Template Parameters

HTag	Hierarchy tag type.
T	Scalar type (e.g. `double`).
N	Spatial dimension (e.g. 2 or 3).
XTag	Optional transform-layer tag. Defaults to HTag.

Definition at line 30 of file transform_hierarchy.h.

Member Typedef Documentation

◆ LT

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

using entttree::TransformSystem< HTag, T, N, XTag >::LT = LocalTransform<HTag,T,N,XTag>

Definition at line 33 of file transform_hierarchy.h.

◆ xfn

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

using entttree::TransformSystem< HTag, T, N, XTag >::xfn = AffineTransform<T,N>

Definition at line 32 of file transform_hierarchy.h.

Constructor & Destructor Documentation

◆ TransformSystem()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

entttree::TransformSystem< HTag, T, N, XTag >::TransformSystem	(	entt::registry &	reg,
		HierarchySystem< HTag > &	hierarchy
	)

inline

Definition at line 50 of file transform_hierarchy.h.

Member Function Documentation

◆ augment_with_transforms()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

template<AnyTraversalConcept Traversal, typename GetId >

auto entttree::TransformSystem< HTag, T, N, XTag >::augment_with_transforms	(	Traversal &&	t,
		GetId &&	get_id
	)		const

inline

Convert a traversal of Node to a traversal of TransformedNode<Node,T,N>.

GetId is a callable which takes a Node& and returns the entt::entity of the node, used to look up the LocalTransform component.

The transform for each node is relative to the traversal root.

Definition at line 178 of file transform_hierarchy.h.

References entttree::make_traversal().

Referenced by entttree::TransformSystem< HTag, T, N, XTag >::traverse().

◆ get_transform()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

std::optional< xfn > entttree::TransformSystem< HTag, T, N, XTag >::get_transform ( entt::entity eid ) const

inline

Get the local transform for an entity, or std::nullopt if none is set.

Definition at line 79 of file transform_hierarchy.h.

◆ hierarchy() [1/2]

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

HierarchySystem< HTag > & entttree::TransformSystem< HTag, T, N, XTag >::hierarchy ( )

inline

Definition at line 56 of file transform_hierarchy.h.

◆ hierarchy() [2/2]

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

const HierarchySystem< HTag > & entttree::TransformSystem< HTag, T, N, XTag >::hierarchy ( ) const

inline

Definition at line 57 of file transform_hierarchy.h.

◆ object_to_world()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

xfn entttree::TransformSystem< HTag, T, N, XTag >::object_to_world ( entt::entity node ) const

inline

Compute the cumulative transform that positions node in the space of the root.

Definition at line 100 of file transform_hierarchy.h.

References entttree::HierarchySystem< HTag >::parent_of().

◆ remove_transform()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

std::optional< LT > entttree::TransformSystem< HTag, T, N, XTag >::remove_transform ( entt::entity eid )

inline

Remove the local transform for an entity. Returns the old component if it existed.

Definition at line 86 of file transform_hierarchy.h.

References entttree::TransformSystem< HTag, T, N, XTag >::on_transform_removed.

◆ set_transform()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

void entttree::TransformSystem< HTag, T, N, XTag >::set_transform	(	entt::entity	eid,
		xfn	xf
	)

inline

Set the local (child-to-parent) transform for an entity.

Definition at line 64 of file transform_hierarchy.h.

References entttree::TransformSystem< HTag, T, N, XTag >::on_transform_changed, and entttree::TransformSystem< HTag, T, N, XTag >::on_transform_set.

◆ traverse()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

auto entttree::TransformSystem< HTag, T, N, XTag >::traverse	(	entt::entity	root,
		SiblingOrder	order
	)		const

inline

Create a traversal which yields TransformedNode<NodeEntry,T,N>.

Each node carries a node_to_root transform accumulated from the traversal root. The traversal includes the root itself with identity transform.

Definition at line 161 of file transform_hierarchy.h.

References entttree::TransformSystem< HTag, T, N, XTag >::augment_with_transforms(), and entttree::HierarchySystem< HTag >::traverse().

◆ xf_between()

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

xfn entttree::TransformSystem< HTag, T, N, XTag >::xf_between	(	entt::entity	from_node,
		entt::entity	to_node
	)		const

inline

Compute the transform from from_node's space to to_node's space.

Both nodes must be in the same tree. The transform is computed via their deepest common ancestor.

Definition at line 120 of file transform_hierarchy.h.

References entttree::HierarchySystem< HTag >::path(), and entttree::HierarchySystem< HTag >::size().

Member Data Documentation

◆ on_transform_changed

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

entt::sigh<void(entt::entity, xfn, xfn)> entttree::TransformSystem< HTag, T, N, XTag >::on_transform_changed

Emitted when an existing transform changes. Args: (entity, old_xf, new_xf).

Definition at line 44 of file transform_hierarchy.h.

Referenced by entttree::TransformSystem< HTag, T, N, XTag >::set_transform().

◆ on_transform_removed

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

entt::sigh<void(entt::entity, xfn)> entttree::TransformSystem< HTag, T, N, XTag >::on_transform_removed

Emitted when a transform is removed from an entity. Args: (entity, old_xf).

Definition at line 42 of file transform_hierarchy.h.

Referenced by entttree::TransformSystem< HTag, T, N, XTag >::remove_transform().

◆ on_transform_set

template<typename HTag , typename T = double, size_t N = 2, typename XTag = HTag>

entt::sigh<void(entt::entity, xfn)> entttree::TransformSystem< HTag, T, N, XTag >::on_transform_set

Emitted when a transform is first set on an entity. Args: (entity, new_xf).

Definition at line 40 of file transform_hierarchy.h.

Referenced by entttree::TransformSystem< HTag, T, N, XTag >::set_transform().

The documentation for this struct was generated from the following file:

include/entttree/transform_hierarchy.h

Public Types

Public Member Functions

Public Attributes

Detailed Description

Member Typedef Documentation

◆ LT

◆ xfn

Constructor & Destructor Documentation

◆ TransformSystem()

Member Function Documentation

◆ augment_with_transforms()

◆ get_transform()

◆ hierarchy() [1/2]

◆ hierarchy() [2/2]

◆ object_to_world()

◆ remove_transform()

◆ set_transform()

◆ traverse()

◆ xf_between()

Member Data Documentation

◆ on_transform_changed

◆ on_transform_removed

◆ on_transform_set