OGRE  2.0
Object-Oriented Graphics Rendering Engine
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Ogre::HardwareBuffer Class Referenceabstract

Abstract class defining common features of hardware buffers. More...

#include <OgreHardwareBuffer.h>

+ Inheritance diagram for Ogre::HardwareBuffer:
+ Collaboration diagram for Ogre::HardwareBuffer:

Public Types

enum  LockOptions {
  HBL_NORMAL, HBL_DISCARD, HBL_READ_ONLY, HBL_NO_OVERWRITE,
  HBL_WRITE_ONLY
}
 Locking options. More...
 
enum  UploadOptions { HBU_DEFAULT = 0x0000, HBU_ON_DEMAND = 0x0001 }
 Device load options The following enum is used to controls how data is loaded to devices in a multi device environment This enum only works with the Direct3D 9 render system (5/2013). More...
 
enum  Usage {
  HBU_STATIC = 1, HBU_DYNAMIC = 2, HBU_WRITE_ONLY = 4, HBU_DISCARDABLE = 8,
  HBU_STATIC_WRITE_ONLY = 5, HBU_DYNAMIC_WRITE_ONLY = 6, HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE = 14
}
 Enums describing buffer usage; not mutually exclusive. More...
 

Public Member Functions

 HardwareBuffer (Usage usage, bool systemMemory, bool useShadowBuffer)
 Constructor, to be called by HardwareBufferManager only. More...
 
virtual ~HardwareBuffer ()
 
virtual void _updateFromShadow (void)
 Updates the real buffer from the shadow buffer, if required. More...
 
virtual void copyData (HardwareBuffer &srcBuffer, size_t srcOffset, size_t dstOffset, size_t length, bool discardWholeBuffer=false)
 Copy data from another buffer into this one. More...
 
virtual void copyData (HardwareBuffer &srcBuffer)
 Copy all data from another buffer into this one. More...
 
size_t getSizeInBytes (void) const
 Returns the size of this buffer in bytes. More...
 
Usage getUsage (void) const
 Returns the Usage flags with which this buffer was created. More...
 
bool hasShadowBuffer (void) const
 Returns whether this buffer has a system memory shadow for quicker reading. More...
 
bool isLocked (void) const
 Returns whether or not this buffer is currently locked. More...
 
bool isSystemMemory (void) const
 Returns whether this buffer is held in system memory. More...
 
virtual void * lock (size_t offset, size_t length, LockOptions options, UploadOptions uploadOpt=HBU_DEFAULT)
 Lock the buffer for (potentially) reading / writing. More...
 
void * lock (LockOptions options, UploadOptions uploadOpt=HBU_DEFAULT)
 Lock the entire buffer for (potentially) reading / writing. More...
 
void operator delete (void *ptr)
 
void operator delete (void *ptr, void *)
 
void operator delete (void *ptr, const char *, int, const char *)
 
void operator delete[] (void *ptr)
 
void operator delete[] (void *ptr, const char *, int, const char *)
 
void * operator new (size_t sz, const char *file, int line, const char *func)
 operator new, with debug line info More...
 
void * operator new (size_t sz)
 
void * operator new (size_t sz, void *ptr)
 placement operator new More...
 
void * operator new[] (size_t sz, const char *file, int line, const char *func)
 array operator new, with debug line info More...
 
void * operator new[] (size_t sz)
 
virtual void readData (size_t offset, size_t length, void *pDest)=0
 Reads data from the buffer and places it in the memory pointed to by pDest. More...
 
void suppressHardwareUpdate (bool suppress)
 Pass true to suppress hardware upload of shadow buffer changes. More...
 
virtual void unlock (void)
 Releases the lock on this buffer. More...
 
virtual void writeData (size_t offset, size_t length, const void *pSource, bool discardWholeBuffer=false)=0
 Writes data to the buffer from an area of system memory; note that you must ensure that your buffer is big enough. More...
 

Protected Member Functions

virtual void * lockImpl (size_t offset, size_t length, LockOptions options)=0
 Internal implementation of lock() More...
 
virtual void unlockImpl (void)=0
 Internal implementation of unlock() More...
 

Protected Attributes

bool mIsLocked
 
size_t mLockSize
 
size_t mLockStart
 
UploadOptions mLockUploadOption
 
HardwareBuffermShadowBuffer
 
bool mShadowUpdated
 
size_t mSizeInBytes
 
bool mSuppressHardwareUpdate
 
bool mSystemMemory
 
Usage mUsage
 
bool mUseShadowBuffer
 

Detailed Description

Abstract class defining common features of hardware buffers.

Remarks
A 'hardware buffer' is any area of memory held outside of core system ram, and in our case refers mostly to video ram, although in theory this class could be used with other memory areas such as sound card memory, custom coprocessor memory etc.
This reflects the fact that memory held outside of main system RAM must be interacted with in a more formal fashion in order to promote cooperative and optimal usage of the buffers between the various processing units which manipulate them.
This abstract class defines the core interface which is common to all buffers, whether it be vertex buffers, index buffers, texture memory or framebuffer memory etc.
Buffers have the ability to be 'shadowed' in system memory, this is because the kinds of access allowed on hardware buffers is not always as flexible as that allowed for areas of system memory - for example it is often either impossible, or extremely undesirable from a performance standpoint to read from a hardware buffer; when writing to hardware buffers, you should also write every byte and do it sequentially. In situations where this is too restrictive, it is possible to create a hardware, write-only buffer (the most efficient kind) and to back it with a system memory 'shadow' copy which can be read and updated arbitrarily. Ogre handles synchronising this buffer with the real hardware buffer (which should still be created with the HBU_DYNAMIC flag if you intend to update it very frequently). Whilst this approach does have its own costs, such as increased memory overhead, these costs can often be outweighed by the performance benefits of using a more hardware efficient buffer. You should look for the 'useShadowBuffer' parameter on the creation methods used to create the buffer of the type you require (see HardwareBufferManager) to enable this feature.

Definition at line 74 of file OgreHardwareBuffer.h.

Member Enumeration Documentation

Locking options.

Enumerator
HBL_NORMAL 

Normal mode, ie allows read/write and contents are preserved.

HBL_DISCARD 

Discards the entire buffer while locking; this allows optimisation to be performed because synchronisation issues are relaxed.

Only allowed on buffers created with the HBU_DYNAMIC flag.

HBL_READ_ONLY 

Lock the buffer for reading only.

Not allowed in buffers which are created with HBU_WRITE_ONLY. Mandatory on static buffers, i.e. those created without the HBU_DYNAMIC flag.

HBL_NO_OVERWRITE 

As HBL_DISCARD, except the application guarantees not to overwrite any region of the buffer which has already been used in this frame, can allow some optimisation on some APIs.

HBL_WRITE_ONLY 

Lock the buffer for writing only.

Definition at line 121 of file OgreHardwareBuffer.h.

Device load options The following enum is used to controls how data is loaded to devices in a multi device environment This enum only works with the Direct3D 9 render system (5/2013).

Enumerator
HBU_DEFAULT 
HBU_ON_DEMAND 

Definition at line 146 of file OgreHardwareBuffer.h.

Enums describing buffer usage; not mutually exclusive.

Enumerator
HBU_STATIC 

Static buffer which the application rarely modifies once created.

Modifying the contents of this buffer will involve a performance hit.

HBU_DYNAMIC 

Indicates the application would like to modify this buffer with the CPU fairly often.

Buffers created with this flag will typically end up in AGP memory rather than video memory.

HBU_WRITE_ONLY 

Indicates the application will never read the contents of the buffer back, it will only ever write data.

Locking a buffer with this flag will ALWAYS return a pointer to new, blank memory rather than the memory associated with the contents of the buffer; this avoids DMA stalls because you can write to a new memory area while the previous one is being used.

HBU_DISCARDABLE 

Indicates that the application will be refilling the contents of the buffer regularly (not just updating, but generating the contents from scratch), and therefore does not mind if the contents of the buffer are lost somehow and need to be recreated.

This allows and additional level of optimisation on the buffer. This option only really makes sense when combined with HBU_DYNAMIC_WRITE_ONLY.

HBU_STATIC_WRITE_ONLY 

Combination of HBU_STATIC and HBU_WRITE_ONLY.

HBU_DYNAMIC_WRITE_ONLY 

Combination of HBU_DYNAMIC and HBU_WRITE_ONLY.

If you use this, strongly consider using HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE instead if you update the entire contents of the buffer very regularly.

HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE 

Combination of HBU_DYNAMIC, HBU_WRITE_ONLY and HBU_DISCARDABLE.

Definition at line 79 of file OgreHardwareBuffer.h.

Constructor & Destructor Documentation

Ogre::HardwareBuffer::HardwareBuffer ( Usage  usage,
bool  systemMemory,
bool  useShadowBuffer 
)
inline

Constructor, to be called by HardwareBufferManager only.

Definition at line 179 of file OgreHardwareBuffer.h.

virtual Ogre::HardwareBuffer::~HardwareBuffer ( )
inlinevirtual

Definition at line 194 of file OgreHardwareBuffer.h.

Member Function Documentation

virtual void Ogre::HardwareBuffer::_updateFromShadow ( void  )
inlinevirtual

Updates the real buffer from the shadow buffer, if required.

Reimplemented in Ogre::GL3PlusHardwareVertexBuffer, Ogre::GL3PlusHardwareIndexBuffer, Ogre::GLHardwareVertexBuffer, and Ogre::GLHardwareIndexBuffer.

Definition at line 324 of file OgreHardwareBuffer.h.

virtual void Ogre::HardwareBuffer::copyData ( HardwareBuffer srcBuffer,
size_t  srcOffset,
size_t  dstOffset,
size_t  length,
bool  discardWholeBuffer = false 
)
inlinevirtual

Copy data from another buffer into this one.

Remarks
Note that the source buffer must not be created with the usage HBU_WRITE_ONLY otherwise this will fail.
Parameters
srcBufferThe buffer from which to read the copied data
srcOffsetOffset in the source buffer at which to start reading
dstOffsetOffset in the destination buffer to start writing
lengthLength of the data to copy, in bytes.
discardWholeBufferIf true, will discard the entire contents of this buffer before copying

Reimplemented in Ogre::D3D11HardwareBuffer, Ogre::GL3PlusHardwareUniformBuffer, Ogre::GL3PlusHardwareVertexBuffer, Ogre::GL3PlusHardwareIndexBuffer, Ogre::GLES2HardwareUniformBuffer, Ogre::GL3PlusHardwareShaderStorageBuffer, Ogre::GL3PlusHardwareCounterBuffer, Ogre::D3D11HardwareIndexBuffer, Ogre::D3D11HardwareUniformBuffer, and Ogre::D3D11HardwareVertexBuffer.

Definition at line 303 of file OgreHardwareBuffer.h.

References lock(), and unlock().

virtual void Ogre::HardwareBuffer::copyData ( HardwareBuffer srcBuffer)
inlinevirtual

Copy all data from another buffer into this one.

Remarks
Normally these buffers should be of identical size, but if they're not, the routine will use the smallest of the two sizes.

Definition at line 317 of file OgreHardwareBuffer.h.

References getSizeInBytes(), and Ogre::min().

size_t Ogre::HardwareBuffer::getSizeInBytes ( void  ) const
inline

Returns the size of this buffer in bytes.

Definition at line 349 of file OgreHardwareBuffer.h.

Referenced by copyData().

Usage Ogre::HardwareBuffer::getUsage ( void  ) const
inline

Returns the Usage flags with which this buffer was created.

Definition at line 351 of file OgreHardwareBuffer.h.

bool Ogre::HardwareBuffer::hasShadowBuffer ( void  ) const
inline

Returns whether this buffer has a system memory shadow for quicker reading.

Definition at line 355 of file OgreHardwareBuffer.h.

bool Ogre::HardwareBuffer::isLocked ( void  ) const
inline

Returns whether or not this buffer is currently locked.

Definition at line 357 of file OgreHardwareBuffer.h.

bool Ogre::HardwareBuffer::isSystemMemory ( void  ) const
inline

Returns whether this buffer is held in system memory.

Definition at line 353 of file OgreHardwareBuffer.h.

void* Ogre::HardwareBuffer::lock ( LockOptions  options,
UploadOptions  uploadOpt = HBU_DEFAULT 
)
inline

Lock the entire buffer for (potentially) reading / writing.

Parameters
optionsLocking options
Returns
Pointer to the locked memory

Definition at line 239 of file OgreHardwareBuffer.h.

template<class Alloc >
void Ogre::AllocatedObject< Alloc >::operator delete ( void *  ptr)
inlineinherited

Definition at line 96 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void Ogre::AllocatedObject< Alloc >::operator delete ( void *  ptr,
void *   
)
inlineinherited

Definition at line 102 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void Ogre::AllocatedObject< Alloc >::operator delete ( void *  ptr,
const char *  ,
int  ,
const char *   
)
inlineinherited

Definition at line 108 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void Ogre::AllocatedObject< Alloc >::operator delete[] ( void *  ptr)
inlineinherited

Definition at line 113 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void Ogre::AllocatedObject< Alloc >::operator delete[] ( void *  ptr,
const char *  ,
int  ,
const char *   
)
inlineinherited

Definition at line 119 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void* Ogre::AllocatedObject< Alloc >::operator new ( size_t  sz,
const char *  file,
int  line,
const char *  func 
)
inlineinherited

operator new, with debug line info

Definition at line 68 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void* Ogre::AllocatedObject< Alloc >::operator new ( size_t  sz)
inlineinherited

Definition at line 73 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void* Ogre::AllocatedObject< Alloc >::operator new ( size_t  sz,
void *  ptr 
)
inlineinherited

placement operator new

Definition at line 79 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void* Ogre::AllocatedObject< Alloc >::operator new[] ( size_t  sz,
const char *  file,
int  line,
const char *  func 
)
inlineinherited

array operator new, with debug line info

Definition at line 86 of file OgreMemoryAllocatedObject.h.

template<class Alloc >
void* Ogre::AllocatedObject< Alloc >::operator new[] ( size_t  sz)
inlineinherited

Definition at line 91 of file OgreMemoryAllocatedObject.h.

void Ogre::HardwareBuffer::suppressHardwareUpdate ( bool  suppress)
inline

Pass true to suppress hardware upload of shadow buffer changes.

Definition at line 361 of file OgreHardwareBuffer.h.

virtual void Ogre::HardwareBuffer::unlock ( void  )
inlinevirtual

Releases the lock on this buffer.

Remarks
Locking and unlocking a buffer can, in some rare circumstances such as switching video modes whilst the buffer is locked, corrupt the contents of a buffer. This is pretty rare, but if it occurs, this method will throw an exception, meaning you must re-upload the data.
Note that using the 'read' and 'write' forms of updating the buffer does not suffer from this problem, so if you want to be 100% sure your data will not be lost, use the 'read' and 'write' forms instead.

Reimplemented in Ogre::DefaultHardwareCounterBuffer, Ogre::GL3PlusDefaultHardwareCounterBuffer, Ogre::DefaultHardwareUniformBuffer, Ogre::GL3PlusDefaultHardwareUniformBuffer, Ogre::GLES2DefaultHardwareUniformBuffer, Ogre::DefaultHardwareIndexBuffer, Ogre::GLDefaultHardwareIndexBuffer, Ogre::GL3PlusDefaultHardwareIndexBuffer, Ogre::GLESDefaultHardwareIndexBuffer, Ogre::GLES2DefaultHardwareIndexBuffer, Ogre::DefaultHardwareVertexBuffer, Ogre::GLDefaultHardwareVertexBuffer, Ogre::GL3PlusDefaultHardwareVertexBuffer, Ogre::GLESDefaultHardwareVertexBuffer, Ogre::GLES2DefaultHardwareVertexBuffer, Ogre::D3D11HardwareIndexBuffer, Ogre::D3D11HardwareUniformBuffer, and Ogre::D3D11HardwareVertexBuffer.

Definition at line 255 of file OgreHardwareBuffer.h.

Referenced by copyData().

virtual void Ogre::HardwareBuffer::writeData ( size_t  offset,
size_t  length,
const void *  pSource,
bool  discardWholeBuffer = false 
)
pure virtual

Writes data to the buffer from an area of system memory; note that you must ensure that your buffer is big enough.

Parameters
offsetThe byte offset from the start of the buffer to start writing
lengthThe size of the data to write to, in bytes
pSourceThe source of the data to be written
discardWholeBufferIf true, this allows the driver to discard the entire buffer when writing, such that DMA stalls can be avoided; use if you can.

Implemented in Ogre::DefaultHardwareCounterBuffer, Ogre::GL3PlusDefaultHardwareCounterBuffer, Ogre::DefaultHardwareUniformBuffer, Ogre::HardwarePixelBuffer, Ogre::GL3PlusDefaultHardwareUniformBuffer, Ogre::GLES2DefaultHardwareUniformBuffer, Ogre::DefaultHardwareIndexBuffer, Ogre::GLDefaultHardwareIndexBuffer, Ogre::GL3PlusDefaultHardwareIndexBuffer, Ogre::GLESDefaultHardwareIndexBuffer, Ogre::GLES2DefaultHardwareIndexBuffer, Ogre::D3D11HardwareBuffer, Ogre::GL3PlusHardwareUniformBuffer, Ogre::DefaultHardwareVertexBuffer, Ogre::GL3PlusHardwareVertexBuffer, Ogre::GL3PlusHardwareIndexBuffer, Ogre::GLHardwareVertexBuffer, Ogre::GLES2HardwareUniformBuffer, Ogre::GLDefaultHardwareVertexBuffer, Ogre::GLHardwareIndexBuffer, Ogre::GL3PlusDefaultHardwareVertexBuffer, Ogre::GL3PlusHardwareShaderStorageBuffer, Ogre::GLESDefaultHardwareVertexBuffer, Ogre::GLES2DefaultHardwareVertexBuffer, Ogre::GL3PlusHardwareCounterBuffer, Ogre::D3D11HardwareIndexBuffer, Ogre::D3D11HardwareUniformBuffer, Ogre::D3D11HardwareVertexBuffer, Ogre::D3D9HardwareIndexBuffer, and Ogre::D3D9HardwareVertexBuffer.

Member Data Documentation

bool Ogre::HardwareBuffer::mIsLocked
protected

Definition at line 162 of file OgreHardwareBuffer.h.

size_t Ogre::HardwareBuffer::mLockSize
protected

Definition at line 164 of file OgreHardwareBuffer.h.

size_t Ogre::HardwareBuffer::mLockStart
protected

Definition at line 163 of file OgreHardwareBuffer.h.

UploadOptions Ogre::HardwareBuffer::mLockUploadOption
protected

Definition at line 165 of file OgreHardwareBuffer.h.

HardwareBuffer* Ogre::HardwareBuffer::mShadowBuffer
protected

Definition at line 168 of file OgreHardwareBuffer.h.

bool Ogre::HardwareBuffer::mShadowUpdated
protected

Definition at line 169 of file OgreHardwareBuffer.h.

size_t Ogre::HardwareBuffer::mSizeInBytes
protected

Definition at line 160 of file OgreHardwareBuffer.h.

bool Ogre::HardwareBuffer::mSuppressHardwareUpdate
protected

Definition at line 170 of file OgreHardwareBuffer.h.

bool Ogre::HardwareBuffer::mSystemMemory
protected

Definition at line 166 of file OgreHardwareBuffer.h.

Usage Ogre::HardwareBuffer::mUsage
protected

Definition at line 161 of file OgreHardwareBuffer.h.

bool Ogre::HardwareBuffer::mUseShadowBuffer
protected

Definition at line 167 of file OgreHardwareBuffer.h.


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