| OGRE 1.11.1 Object-Oriented Graphics Rendering Engine

Public Types | Public Member Functions | List of all members
Ogre::GL3PlusHardwareShaderStorageBuffer Class Reference

Specialisation of HardwareUniformBuffer for the OpenGL Shader Storage Buffer. More...

`#include <OgreGL3PlusHardwareShaderStorageBuffer.h>`

Inheritance diagram for Ogre::GL3PlusHardwareShaderStorageBuffer:
[legend]

## Public Types
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
| GL3PlusHardwareShaderStorageBuffer (HardwareBufferManagerBase *mgr, size_t bufferSize, HardwareBuffer::Usage usage, bool useShadowBuffer, const String &name)
virtual void | _updateFromShadow (void)
| Updates the real buffer from the shadow buffer, if required. More...
void | copyData (HardwareBuffer &srcBuffer, size_t srcOffset, size_t dstOffset, size_t length, bool discardWholeBuffer=false)
| See HardwareBuffer. More...
virtual void | copyData (HardwareBuffer &srcBuffer)
| Copy all data from another buffer into this one. More...
GLint | getGLBufferBinding (void) const
GLuint | getGLBufferId (void) const
HardwareBufferManagerBase * | getManager () const
| Return the manager of this buffer, if any. More...
const String & | getName () const
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)
| Lock the buffer for (potentially) reading / writing. More...
void * | lock (LockOptions options)
void | readData (size_t offset, size_t length, void *pDest)
| See HardwareBuffer. More...
void | setGLBufferBinding (GLint binding)
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...
void | writeData (size_t offset, size_t length, const void *pSource, bool discardWholeBuffer=false)
| See HardwareBuffer. More...

## Detailed Description

Specialisation of HardwareUniformBuffer for the OpenGL Shader Storage Buffer.

## Member Enumeration Documentation

## ◆ Usage

enum Ogre::HardwareBuffer::Usage
| inherited

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

enum Ogre::HardwareBuffer::LockOptions
| inherited

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

## ◆ GL3PlusHardwareShaderStorageBuffer()

Ogre::GL3PlusHardwareShaderStorageBuffer::GL3PlusHardwareShaderStorageBuffer | ( | HardwareBufferManagerBase * | mgr,
|  | size_t | bufferSize,
|  | HardwareBuffer::Usage | usage,
|  | bool | useShadowBuffer,
|  | const String & | name
| ) |  |

## Member Function Documentation

## ◆ readData()

void Ogre::GL3PlusHardwareShaderStorageBuffer::readData | ( | size_t | offset,
|  | size_t | length,
|  | void * | pDest
| ) |  |
| virtual

See HardwareBuffer.

Implements Ogre::HardwareBuffer.

## ◆ writeData()

void Ogre::GL3PlusHardwareShaderStorageBuffer::writeData | ( | size_t | offset,
|  | size_t | length,
|  | const void * | pSource,
|  | bool | discardWholeBuffer = `false`
| ) |  |
| virtual

See HardwareBuffer.

Implements Ogre::HardwareBuffer.

## ◆ copyData() [1/2]

void Ogre::GL3PlusHardwareShaderStorageBuffer::copyData | ( | HardwareBuffer & | srcBuffer,
|  | size_t | srcOffset,
|  | size_t | dstOffset,
|  | size_t | length,
|  | bool | discardWholeBuffer = `false`
| ) |  |
| virtual

See HardwareBuffer.

Reimplemented from Ogre::HardwareBuffer.

## ◆ getGLBufferId()

GLuint Ogre::GL3PlusHardwareShaderStorageBuffer::getGLBufferId | ( | void |  | ) | const
| inline

References Ogre::GL3PlusHardwareBuffer::getGLBufferId().

## ◆ setGLBufferBinding()

void Ogre::GL3PlusHardwareShaderStorageBuffer::setGLBufferBinding | ( | GLint | binding | ) |

## ◆ getGLBufferBinding()

GLint Ogre::GL3PlusHardwareShaderStorageBuffer::getGLBufferBinding | ( | void |  | ) | const
| inline

## ◆ lock() [1/2]

virtual void* Ogre::HardwareBuffer::lock | ( | size_t | offset,
|  | size_t | length,
|  | LockOptions | options
| ) |  |
| inline virtual inherited

Lock the buffer for (potentially) reading / writing.

Parameters

  offset | The byte offset from the start of the buffer to lock
  length | The size of the area to lock, in bytes
  options | Locking 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().

## ◆ lock() [2/2]

void* Ogre::HardwareBuffer::lock | ( | LockOptions | options | ) |
| inline inherited

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 |  | ) |
| inline virtual inherited

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().

## ◆ copyData() [2/2]

virtual void Ogre::HardwareBuffer::copyData | ( | HardwareBuffer & | srcBuffer | ) |
| inline virtual inherited

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 |  | ) |
| inline virtual inherited

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

Reimplemented in Ogre::D3D11HardwareBuffer, Ogre::GLES2HardwareIndexBuffer, Ogre::GLES2HardwareVertexBuffer, Ogre::GL3PlusHardwareVertexBuffer, Ogre::GL3PlusHardwareIndexBuffer, Ogre::GLHardwareVertexBuffer, and Ogre::GLHardwareIndexBuffer.

## ◆ getSizeInBytes()

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

Returns the size of this buffer in bytes.

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

## ◆ getUsage()

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

Returns the Usage flags with which this buffer was created.

## ◆ isSystemMemory()

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

Returns whether this buffer is held in system memory.

## ◆ hasShadowBuffer()

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

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

## ◆ isLocked()

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

Returns whether or not this buffer is currently locked.

## ◆ suppressHardwareUpdate()

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

Pass true to suppress hardware upload of shadow buffer changes.

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

- OgreGL3PlusHardwareShaderStorageBuffer.h