EngineDeterministicComponent Class Reference

#include <EngineDeterministicComponent.h>

Inheritance diagram for EngineDeterministicComponent:

Public Member Functions
	EngineDeterministicComponent ()
virtual	~EngineDeterministicComponent ()
void	restart (int frameTimeMs, RandomEngineType rngType)
void	finish ()
bool	isActive () const

Private Member Functions
virtual int64_t	tickCount () const override
virtual void	swapBuffers () override
virtual void	removeNotify () override
Private Member Functions inherited from ProxyPlatform
	ProxyPlatform (Platform *base=nullptr)
virtual	~ProxyPlatform ()=default
virtual std::unique_ptr< PlatformWindow >	createWindow () override
virtual std::unique_ptr< PlatformEventLoop >	createEventLoop () override
virtual std::vector< PlatformGamepad * >	gamepads () override
virtual void	setCursorShown (bool cursorShown) override
virtual bool	isCursorShown () const override
virtual std::vector< Recti >	displayGeometries () const override
virtual void	showMessageBox (const std::string &title, const std::string &message) const override
virtual int64_t	tickCount () const override
Private Member Functions inherited from ProxyBase< Platform >
	ProxyBase (Platform *base)
Platform *	base () const
void	setBase (Platform *base)
Platform *	nonNullBase () const
Private Member Functions inherited from Platform
virtual	~Platform ()=default
virtual std::unique_ptr< PlatformWindow >	createWindow ()=0
virtual std::unique_ptr< PlatformEventLoop >	createEventLoop ()=0
virtual std::vector< PlatformGamepad * >	gamepads ()=0
virtual void	setCursorShown (bool cursorShown)=0
virtual bool	isCursorShown () const =0
virtual std::vector< Recti >	displayGeometries () const =0
virtual void	showMessageBox (const std::string &title, const std::string &message) const =0
virtual int64_t	tickCount () const =0
Private Member Functions inherited from ProxyOpenGLContext
	ProxyOpenGLContext (PlatformOpenGLContext *base=nullptr)
virtual	~ProxyOpenGLContext ()=default
virtual bool	bind () override
virtual bool	unbind () override
virtual void *	nativeHandle () override
virtual void	swapBuffers () override
virtual void *	getProcAddress (const char *name) override
Private Member Functions inherited from ProxyBase< PlatformOpenGLContext >
	ProxyBase (PlatformOpenGLContext *base)
PlatformOpenGLContext *	base () const
void	setBase (PlatformOpenGLContext *base)
PlatformOpenGLContext *	nonNullBase () const
Private Member Functions inherited from PlatformOpenGLContext
virtual	~PlatformOpenGLContext ()=default
virtual bool	bind ()=0
virtual bool	unbind ()=0
virtual void *	nativeHandle ()=0
virtual void	swapBuffers ()=0
virtual void *	getProcAddress (const char *name)=0
Private Member Functions inherited from PlatformApplicationAware
	~PlatformApplicationAware ()=default
PlatformApplication *	application () const
template<class T >
T *	component () const
virtual void	installNotify ()
virtual void	removeNotify ()

Private Attributes
bool	_active = false
int64_t	_tickCount = 0
int	_frameTimeMs = 0
RandomEngineType	_oldRandomEngineType = RANDOM_ENGINE_MERSENNE_TWISTER

Friends
class	PlatformIntrospection

Additional Inherited Members
Static Private Member Functions inherited from Platform
static std::unique_ptr< Platform >	createStandardPlatform ()

Detailed Description

This component can be used to make the engine more deterministic. It replaces the system timer with a fake one that advances by a fixed number of milliseconds each frame, and also resets the global random number generator.

Note that this component is intentionally very dumb. All the methods just do exactly what you would expect right away, so where you're calling them from becomes very important. E.g. calling restart from an event handler would probably make little sense.

Constructor & Destructor Documentation

EngineDeterministicComponent()

EngineDeterministicComponent::EngineDeterministicComponent ( )

default

~EngineDeterministicComponent()

EngineDeterministicComponent::~EngineDeterministicComponent ( )

virtualdefault

Member Function Documentation

finish()

void EngineDeterministicComponent::finish

(

)

Leaves deterministic mode if currently is in it, does nothing otherwise.

isActive()

bool EngineDeterministicComponent::isActive ( ) const

inline

removeNotify()

void EngineDeterministicComponent::removeNotify ( )

overrideprivatevirtual

Called before removal from a PlatformApplication. application() will return non-null inside this function.

Reimplemented from PlatformApplicationAware.

restart()

void EngineDeterministicComponent::restart	(	int	frameTimeMs,
		RandomEngineType	rngType
	)

Starts a new deterministic segment, resetting all state - rolls the tick count back to zero, and resets grng.

Why we're passing frame time in milliseconds here and not setting the target fps directly? For example, it is possible to target 60fps, but since the platform API is in milliseconds, this will result in staggered frame times, with every 1st and 2nd frame taking 17ms, and every 3rd one taking 16ms. This might result in some non-determinism down the line. Unlikely to really affect anything, but we'd rather not find out.

Parameters

frameTimeMs	Frame time to use inside the segment, in milliseconds.
rngType	Random engine type to use inside the segment.

swapBuffers()

void EngineDeterministicComponent::swapBuffers ( )

overrideprivatevirtual

Reimplemented from ProxyOpenGLContext.

tickCount()

int64_t EngineDeterministicComponent::tickCount ( ) const

overrideprivatevirtual

Returns

Current value of a monotonic clock in milliseconds.

Reimplemented from ProxyPlatform.

Friends And Related Function Documentation

PlatformIntrospection

friend class PlatformIntrospection

friend

Member Data Documentation

_active

bool EngineDeterministicComponent::_active = false

private

_frameTimeMs

int EngineDeterministicComponent::_frameTimeMs = 0

private

_oldRandomEngineType

RandomEngineType EngineDeterministicComponent::_oldRandomEngineType = RANDOM_ENGINE_MERSENNE_TWISTER

private

_tickCount

int64_t EngineDeterministicComponent::_tickCount = 0

private

---

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

• src/Engine/Components/Deterministic/EngineDeterministicComponent.h
• src/Engine/Components/Deterministic/EngineDeterministicComponent.cpp