plCollectionResource Class Reference

An plCollectionResource is used to tell the engine about resources that it should preload in the background. More...

#include <CollectionResource.h>

Inheritance diagram for plCollectionResource:

Public Member Functions
void	RegisterNames ()
	Registers the named resources in the collection with the plResourceManager, such that they can be loaded by those names.
void	UnregisterNames ()
	Removes the registered names from the plResourceManager.
bool	PreloadResources (plUInt32 uiNumResourcesToPreload=plMath::MaxValue< plUInt32 >())
	Puts up to the given number of resources for which a resource type could be found into the preload queue of the plResourceManager.
bool	IsLoadingFinished (float *out_pProgress=nullptr) const
	Returns true if all resources added for preloading via PreloadResources have finished loading. if out_progress is defined:
const plCollectionResourceDescriptor &	GetDescriptor () const
	Returns the resource descriptor for this resource.
plArrayPtr< const plTypelessResourceHandle >	GetPreloadedResources () const
	Returns the current list of resources that have already been added to the preload list. See PreloadResources().
Public Member Functions inherited from plResource
PL_ALWAYS_INLINE const plString &	GetResourceID () const
	Returns the unique ID that identifies this resource. On a file resource this might be a path. Can also be a GUID or any other scheme that uniquely identifies the resource.
PL_ALWAYS_INLINE plUInt64	GetResourceIDHash () const
	Returns the hash of the unique ID.
void	SetResourceDescription (plStringView sDescription)
	The resource description allows to store an additional string that might be more descriptive during debugging, than the unique ID.
const plString &	GetResourceDescription () const
	The resource description allows to store an additional string that might be more descriptive during debugging, than the unique ID.
const plString &	GetResourceIdOrDescription () const
	The returns the resource description, if available, otherwise the resource ID.
PL_ALWAYS_INLINE plResourceState	GetLoadingState () const
	Returns the current state in which this resource is in.
PL_ALWAYS_INLINE plUInt8	GetNumQualityLevelsDiscardable () const
	Returns the current maximum quality level that the resource could have.
PL_ALWAYS_INLINE plUInt8	GetNumQualityLevelsLoadable () const
	Returns how many quality levels the resource may additionally load.
float	GetLoadingPriority (plTime now) const
	Returns the priority that is used by the resource manager to determine which resource to load next.
plResourcePriority	GetPriority () const
	Returns the current resource priority.
void	SetPriority (plResourcePriority priority)
	Changes the current resource priority.
PL_ALWAYS_INLINE const plBitflags< plResourceFlags > &	GetBaseResourceFlags () const
	Returns the basic flags for the resource type. Mostly used the resource manager.
PL_ALWAYS_INLINE const MemoryUsage &	GetMemoryUsage () const
	Returns the information about the current memory usage of the resource.
PL_ALWAYS_INLINE plTime	GetLastAcquireTime () const
	Returns the time at which the resource was (tried to be) acquired last. If a resource is acquired using plResourceAcquireMode::PointerOnly, this does not update the last acquired time, since the resource is not acquired for full use.
PL_ALWAYS_INLINE plInt32	GetReferenceCount () const
	Returns the reference count of this resource.
PL_ALWAYS_INLINE const plTimestamp &	GetLoadedFileModificationTime () const
	Returns the modification date of the file from which this resource was loaded.
PL_ALWAYS_INLINE plUInt32	GetCurrentResourceChangeCounter () const
	Returns the current value of the resource change counter. Can be used to detect whether the resource has changed since using it last time.
PL_ALWAYS_INLINE void	IncResourceChangeCounter ()
	Allows to manually increase the resource change counter to signal that dependent code might need to update.
virtual void	ResetResource ()
	If the resource has modifications from the original state, it should reset itself to that state now (or force a reload on itself).
void	PrintHandleStackTraces ()
	Prints the stack-traces for all handles that currently reference this resource.
Public Member Functions inherited from plReflectedClass
virtual const plRTTI *	GetDynamicRTTI () const
bool	IsInstanceOf (const plRTTI *pType) const
	Returns whether the type of this instance is of the given type or derived from it.
template<typename T >
PL_ALWAYS_INLINE bool	IsInstanceOf () const
	Returns whether the type of this instance is of the given type or derived from it.

Private Member Functions
virtual plResourceLoadDesc	UnloadData (Unload WhatToUnload) override
	Requests the resource to unload another quality level. If bFullUnload is true, the resource should unload all data, because it is going to be deleted afterwards.
virtual plResourceLoadDesc	UpdateContent (plStreamReader *Stream) override
	Called whenever more data for the resource is available. The resource must read the stream to update it's data.
virtual void	UpdateMemoryUsage (MemoryUsage &out_NewMemoryUsage) override
	This function must be overridden by all resource types.

Additional Inherited Members
Static Public Member Functions inherited from plNoBase
static const plRTTI *	GetStaticRTTI ()
Public Attributes inherited from plResource
plEvent< const plResourceEvent &, plMutex >	m_ResourceEvents
Protected Types inherited from plResource
enum class	DoUpdate { OnMainThread , OnAnyThread }
enum class	Unload { AllQualityLevels , OneQualityLevel }
Protected Member Functions inherited from plResource
	plResource (DoUpdate ResourceUpdateThread, plUInt8 uiQualityLevelsLoadable)
	Default constructor.
virtual	~plResource ()
	virtual destructor.
MemoryUsage &	ModifyMemoryUsage ()
	Non-const version for resources that want to write this variable directly.
void	SetIsReloadable (bool bIsReloadable)
	Call this to specify whether a resource is reloadable.
void	SetHasLoadingFallback (bool bHasLoadingFallback)
	Used internally by the code injection macros.

Detailed Description

An plCollectionResource is used to tell the engine about resources that it should preload in the background.

Collection resources can be used to improve the user experience by ensuring data is already (more likely) available when it is needed. For instance when a player walks into a longer corridor, a collection resource can be triggered to preload the data that will be needed when he reaches the door at the end of the corridor. In scenes this can be achieved using an plCollectionComponent.

Collection resources can also be used to query how much percent of the references resources are already loaded, which enables building progress bars or allowing functionality only after all necessary data is available.

Finally, collections can also be used to register resources with a nice name, such that it can be referenced in code by that name. This is useful if you want to reference some asset in code with a readable resource ID, and may want to change which resource is referenced at a later time. For example the nice name "Avatar" could point to some dummy mesh at the beginning of the project, and be updated to point to something else later, without the need to change the code.

Note

Once plCollectionResource::PreloadResources() has been triggered, the resource will hold a handle to all referenced resources, meaning those resources cannot get unloaded anymore. Make sure to discard the collection resource if the data it references should get freed up.

Member Function Documentation

IsLoadingFinished()

bool plCollectionResource::IsLoadingFinished

(

float *

out_pProgress = nullptr

)

const

Returns true if all resources added for preloading via PreloadResources have finished loading. if out_progress is defined:

• Assigns a value between 0.0 and 1.0 representing how many of the collection's resources are in a loaded state at the moment.
• Always assigns 1.0 if all resources are in a loaded state.
• Always assigns 1.0 if the collection contains no resources, or PreloadResources() was not triggered previously. Note: the progress can reach at maximum the fraction of resources that have been queued for preloading via PreloadResources. The progress will only reach 1.0 if all resources of this collection have been queued via PreloadResources and finished loading.

PreloadResources()

bool plCollectionResource::PreloadResources

(

plUInt32

uiNumResourcesToPreload = plMath::MaxValue<plUInt32>()

)

Puts up to the given number of resources for which a resource type could be found into the preload queue of the plResourceManager.

This has to be called manually. It will return false if no more resources can be queued for preloading. This can be used as a workflow where PreloadResources and IsLoadingFinished are called repeadedly in tandem, so only a smaller fraction of resources gets queued and waited for, to allow simple resource load-balancing.

RegisterNames()

void plCollectionResource::RegisterNames

(

)

Registers the named resources in the collection with the plResourceManager, such that they can be loaded by those names.

Note

This has to be called MANUALLY on collection resources, they do NOT do this automatically when loaded. Since resources are streamed, there is no guaranteed point in time when those names would be registered, which would introduce timing issues, where sometimes the name is registered when it is used and sometimes not. By calling this manually, the point in time where this is done is fixed and guaranteed.

Calling this twice has no effect.

UnloadData()

plResourceLoadDesc plCollectionResource::UnloadData ( Unload WhatToUnload )

overrideprivatevirtual

Requests the resource to unload another quality level. If bFullUnload is true, the resource should unload all data, because it is going to be deleted afterwards.

Implements plResource.

UnregisterNames()

void plCollectionResource::UnregisterNames

(

)

Removes the registered names from the plResourceManager.

Calling this twice has no effect.

UpdateContent()

plResourceLoadDesc plCollectionResource::UpdateContent ( plStreamReader * pStream )

overrideprivatevirtual

Called whenever more data for the resource is available. The resource must read the stream to update it's data.

pStream may be nullptr in case the resource data could not be found.

Implements plResource.

UpdateMemoryUsage()

void plCollectionResource::UpdateMemoryUsage ( MemoryUsage & out_NewMemoryUsage )

overrideprivatevirtual

This function must be overridden by all resource types.

It has to compute the memory used by this resource. It is called by the resource manager whenever the resource's data has been loaded or unloaded.

Implements plResource.

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The documentation for this class was generated from the following files:

• Code/Engine/Core/Collection/CollectionResource.h
• Code/Engine/Core/Collection/Implementation/CollectionResource.cpp