OGRE  1.12.3
Object-Oriented Graphics Rendering Engine
Ogre::HardwareIndexBuffer Class Referenceabstract

Specialisation of HardwareBuffer for vertex index buffers, still abstract. More...

#include <OgreHardwareIndexBuffer.h>

+ Inheritance diagram for Ogre::HardwareIndexBuffer:

Public Types

enum  IndexType { IT_16BIT, IT_32BIT }
 
enum  LockOptions {
  HBL_NORMAL, HBL_DISCARD, HBL_READ_ONLY, HBL_NO_OVERWRITE,
  HBL_WRITE_ONLY
}
 Locking options. More...
 
enum  Usage {
  HBU_STATIC = 1, HBU_DYNAMIC = 2, HBU_WRITE_ONLY = 4, HBU_DISCARDABLE = 8,
  HBU_STATIC_WRITE_ONLY = HBU_STATIC | HBU_WRITE_ONLY, HBU_DYNAMIC_WRITE_ONLY = HBU_DYNAMIC | HBU_WRITE_ONLY, HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE = HBU_DYNAMIC_WRITE_ONLY | HBU_DISCARDABLE
}
 Enums describing buffer usage; not mutually exclusive. More...
 

Public Member Functions

 HardwareIndexBuffer (HardwareBufferManagerBase *mgr, IndexType idxType, size_t numIndexes, HardwareBuffer::Usage usage, bool useSystemMemory, bool useShadowBuffer)
 Should be called by HardwareBufferManager. More...
 
 ~HardwareIndexBuffer ()
 
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 getIndexSize (void) const
 Get the size in bytes of each index. More...
 
HardwareBufferManagerBasegetManager () const
 Return the manager of this buffer, if any. More...
 
size_t getNumIndexes (void) const
 Get the number of indexes in this buffer. More...
 
size_t getSizeInBytes (void) const
 Returns the size of this buffer in bytes. More...
 
IndexType getType (void) const
 Get the type of indexes used in this buffer. 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)
 Lock the buffer for (potentially) reading / writing. More...
 
void * lock (LockOptions options)
 
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...
 

Detailed Description

Specialisation of HardwareBuffer for vertex index buffers, still abstract.

Member Enumeration Documentation

◆ IndexType

Enumerator
IT_16BIT 
IT_32BIT 

◆ Usage

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.

This is the least optimal buffer setting.

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.

However, you may read from it’s shadow buffer if you set one up

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 This is the optimal buffer usage setting.

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 This means that you expect to replace the entire contents of the buffer on an extremely regular basis, most likely every frame.

By selecting this option, you free the system up from having to be concerned about losing the existing contents of the buffer at any time, because if it does lose them, you will be replacing them next frame anyway. On some platforms this can make a significant performance difference, so you should try to use this whenever you have a buffer you need to update regularly. Note that if you create a buffer this way, you should use the HBL_DISCARD flag when locking the contents of it for writing.

◆ LockOptions

Locking options.

Enumerator
HBL_NORMAL 

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

This kind of lock allows reading and writing from the buffer - it’s also the least optimal because basically you’re telling the card you could be doing anything at all. If you’re not using a shadow buffer, it requires the buffer to be transferred from the card and back again. If you’re using a shadow buffer the effect is minimal.

HBL_DISCARD 

Discards the entire buffer while locking.

This means you are happy for the card to discard the entire current contents of the buffer. Implicitly this means you are not going to read the data - it also means that the card can avoid any stalls if the buffer is currently being rendered from, because it will actually give you an entirely different one. Use this wherever possible when you are locking a buffer which was not created with a shadow buffer. If you are using a shadow buffer it matters less, although with a shadow buffer it’s preferable to lock the entire buffer at once, because that allows the shadow buffer to use HBL_DISCARD when it uploads the updated contents to the real buffer. 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.

This is only useful on buffers with no shadow buffer.

HBL_WRITE_ONLY 

Lock the buffer for writing only.

Constructor & Destructor Documentation

◆ HardwareIndexBuffer()

Ogre::HardwareIndexBuffer::HardwareIndexBuffer ( HardwareBufferManagerBase mgr,
IndexType  idxType,
size_t  numIndexes,
HardwareBuffer::Usage  usage,
bool  useSystemMemory,
bool  useShadowBuffer 
)

Should be called by HardwareBufferManager.

◆ ~HardwareIndexBuffer()

Ogre::HardwareIndexBuffer::~HardwareIndexBuffer ( )

Member Function Documentation

◆ getManager()

HardwareBufferManagerBase* Ogre::HardwareIndexBuffer::getManager ( ) const
inline

Return the manager of this buffer, if any.

◆ getType()

IndexType Ogre::HardwareIndexBuffer::getType ( void  ) const
inline

Get the type of indexes used in this buffer.

Referenced by Ogre::Lod0Stripifier::~Lod0Stripifier().

◆ getNumIndexes()

size_t Ogre::HardwareIndexBuffer::getNumIndexes ( void  ) const
inline

Get the number of indexes in this buffer.

◆ getIndexSize()

size_t Ogre::HardwareIndexBuffer::getIndexSize ( void  ) const
inline

Get the size in bytes of each index.

Referenced by Ogre::Lod0Stripifier::~Lod0Stripifier().

◆ lock() [1/2]

virtual void* Ogre::HardwareBuffer::lock ( size_t  offset,
size_t  length,
LockOptions  options 
)
inlinevirtualinherited

Lock the buffer for (potentially) reading / writing.

Parameters
offsetThe byte offset from the start of the buffer to lock
lengthThe size of the area to lock, in bytes
optionsLocking options
Returns
Pointer to the locked memory

Reimplemented in Ogre::DefaultHardwareCounterBuffer, Ogre::DefaultHardwareUniformBuffer, Ogre::HardwarePixelBuffer, Ogre::DefaultHardwareIndexBuffer, Ogre::DefaultHardwareVertexBuffer, Ogre::D3D11HardwareUniformBuffer, Ogre::D3D11HardwareVertexBuffer, and Ogre::D3D11HardwareIndexBuffer.

References Ogre::Exception::ERR_INVALIDPARAMS, and OGRE_EXCEPT.

Referenced by Ogre::HardwareBuffer::copyData(), Ogre::HardwareBufferLockGuard::lock(), and Ogre::Lod0Stripifier::~Lod0Stripifier().

◆ lock() [2/2]

void* Ogre::HardwareBuffer::lock ( LockOptions  options)
inlineinherited

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ unlock()

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

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::DefaultHardwareUniformBuffer, Ogre::DefaultHardwareIndexBuffer, Ogre::DefaultHardwareVertexBuffer, Ogre::D3D11HardwareUniformBuffer, Ogre::D3D11HardwareVertexBuffer, and Ogre::D3D11HardwareIndexBuffer.

Referenced by Ogre::HardwareBuffer::copyData(), and Ogre::Lod0Stripifier::~Lod0Stripifier().

◆ readData()

virtual void Ogre::HardwareBuffer::readData ( size_t  offset,
size_t  length,
void *  pDest 
)
pure virtualinherited

◆ writeData()

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

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::DefaultHardwareUniformBuffer, Ogre::HardwarePixelBuffer, Ogre::DefaultHardwareIndexBuffer, Ogre::D3D11HardwareBuffer, Ogre::DefaultHardwareVertexBuffer, Ogre::GLES2HardwareIndexBuffer, Ogre::GLES2HardwareVertexBuffer, Ogre::GL3PlusHardwareShaderStorageBuffer, Ogre::GLHardwareVertexBuffer, Ogre::GL3PlusHardwareUniformBuffer, Ogre::GLES2HardwareUniformBuffer, Ogre::GLHardwareIndexBuffer, Ogre::GL3PlusHardwareCounterBuffer, Ogre::GL3PlusHardwareIndexBuffer, Ogre::GL3PlusHardwareVertexBuffer, Ogre::D3D11HardwareUniformBuffer, Ogre::D3D11HardwareVertexBuffer, Ogre::D3D11HardwareIndexBuffer, Ogre::D3D9HardwareIndexBuffer, and Ogre::D3D9HardwareVertexBuffer.

◆ copyData() [1/2]

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

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::GLES2HardwareIndexBuffer, Ogre::GLES2HardwareVertexBuffer, Ogre::GL3PlusHardwareShaderStorageBuffer, Ogre::GL3PlusHardwareUniformBuffer, Ogre::GLES2HardwareUniformBuffer, Ogre::GL3PlusHardwareCounterBuffer, Ogre::GL3PlusHardwareVertexBuffer, Ogre::GL3PlusHardwareIndexBuffer, Ogre::D3D11HardwareUniformBuffer, Ogre::D3D11HardwareVertexBuffer, and Ogre::D3D11HardwareIndexBuffer.

References Ogre::HardwareBuffer::lock(), and Ogre::HardwareBuffer::unlock().

◆ copyData() [2/2]

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

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.

References Ogre::HardwareBuffer::getSizeInBytes().

◆ _updateFromShadow()

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

◆ getSizeInBytes()

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

Returns the size of this buffer in bytes.

Referenced by Ogre::HardwareBuffer::copyData().

◆ getUsage()

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

Returns the Usage flags with which this buffer was created.

Referenced by Ogre::Lod0Stripifier::~Lod0Stripifier().

◆ isSystemMemory()

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

Returns whether this buffer is held in system memory.

◆ hasShadowBuffer()

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

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

Referenced by Ogre::Lod0Stripifier::~Lod0Stripifier().

◆ isLocked()

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

Returns whether or not this buffer is currently locked.

◆ suppressHardwareUpdate()

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

Pass true to suppress hardware upload of shadow buffer changes.


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