Buffer Class Reference

#include <ImFusion/Core/GL/Buffer.h>

Wrapper class for OpenGL Buffer Objects. More...

Inheritance diagram for Buffer:

Detailed Description

Wrapper class for OpenGL Buffer Objects.

OpenGL buffers serve many different purposes of which this base class implements the common interface. However, this class is not meant to be used directly. Instead you should use one of the specializations such as VertexBuffer, ShaderStorageBuffer, etc. instead for improved type safety. Furthermore, each specialization provides an extended API that is tailored to its buffer type.

Note

As with most OpenGL objects, this class is bind-sensitive: You need to call bind() to bind a Buffer to the current OpenGL context before calling any modifying member functions.

See also

https://www.khronos.org/opengl/wiki/Buffer_Object

Public Types
enum class	Target {   Array = 0x8892 , AtomicCounter = 0x92C0 , CopyRead = 0x8F36 , CopyWrite = 0x8F37 ,   DrawIndirect = 0x8F3F , ElementArray = 0x8893 , PixelPack = 0x88EB , PixelUnpack = 0x88EC ,   ShaderStorage = 0x90D2 , Texture = 0x8C2A , TransformFeedback = 0x8C8E , Uniform = 0x8A11 }
	Enumeration of the different OpenGL buffer types. More...
enum class	Usage {   StreamDraw = 0x88E0 , StreamRead = 0x88E1 , StreamCopy = 0x88E2 , StaticDraw = 0x88E4 ,   StaticRead = 0x88E5 , StaticCopy = 0x88E6 , DynamicDraw = 0x88E8 , DynamicRead = 0x88E9 ,   DynamicCopy = 0x88EA }
	Enumeration for usage pattern hints to provide to the GPU when allocating data. More...

Public Member Functions
	Buffer (Target target, Usage usage)
	Creates a new Buffer.
void	bind () const
	Binds the buffer to the target given during construction.
Usage	usageHint () const
	Returns the buffer usage hint passed to OpenGL during allocation.
void	setUsageHint (Usage value)
	Sets the buffer usage hint passed to OpenGL during allocation.
uint32_t	id () const
	Return a handle to the internal OpenGL buffer object.

Static Public Member Functions
static void	unbind (Target target)
	Binds 0 to the specified target.

Protected Member Functions
void	allocateBuffer (int64_t numBytes)
	Allocates storage on the GPU for this buffer object.
template<typename... Ts>
void	setSubData (size_t offset, Utils::Span< Ts >... data)
	Upload data into the buffer starting at the given offset.
template<typename... Ts>
size_t	getBufferSize (Utils::Span< Ts >... data) const
	Compute the total number of bytes used by all provided data together.

Static Protected Member Functions
static void	glBufferSubDataImpl (Target target, int64_t offset, int64_t size, const void *data)
	forwards to OpenGL's glBufferSubData().
static void	glGetBufferSubDataImpl (Target target, int64_t offset, int64_t size, void *data)
	forwards to OpenGL's glGetBufferSubData().

Protected Attributes
const Target	m_target
	Target binding point for the buffer, will never change for a Buffer instance.
Usage	m_usageHint
	Buffer usage hint passed to OpenGL unless explicitly specified otherwise.
uint32_t	m_id = 0
	Internal OpenGL handle to buffer object.
int64_t	m_bufferSize = 0
	Number of bytes allocated on the GPU.

Member Enumeration Documentation

Target

enum class Target

strong

Enumeration of the different OpenGL buffer types.

If you use the specializations of Buffer, you will not need to use these.

Usage

enum class Usage

strong

Enumeration for usage pattern hints to provide to the GPU when allocating data.

Enumerator
StreamDraw	The data is modified once and used at most a few times; it is modified by the application, and used as the source for GL drawing and image specification commands.
StreamRead	The data is modified once and used at most a few times; it is modified by reading data from the GL device, and used to return that data when queried by the application.
StreamCopy	The data is modified once and used at most a few times; it is modified by reading data from the GL device, and used as the source for GL drawing and image specification commands.
StaticDraw	The data is modified once and used many times; the data is modified by the application, and used as the source for GL drawing and image specification commands.
StaticRead	The data is modified once and used many times; it is modified by reading data from the GL device, and used to return that data when queried by the application.
StaticCopy	The data is modified once and used many times; it is modified by reading data from the GL device, and used as the source for GL drawing and image specification commands.
DynamicDraw	The data is modified repeatedly and used many times; it is modified by the application, and used as the source for GL drawing and image specification commands.
DynamicRead	The data is modified repeatedly and used many times; it is modified by reading data from the GL device, and used to return that data when queried by the application.
DynamicCopy	The data is modified repeatedly and used many times; it is modified by reading data from the GL device, and used as the source for GL drawing and image specification commands.

Constructor & Destructor Documentation

Buffer()

Buffer	(	Target	target,
		Usage	usage )

Creates a new Buffer.

Needs a valid OpenGL context.

Exceptions

std::runtime_error

if the corresponding OpenGL buffer object could not be created.

Member Function Documentation

id()

uint32_t id

(

)

const

Return a handle to the internal OpenGL buffer object.

Note

Use with care! Any changes made to the buffer with this handle may not be reflected by this object.

allocateBuffer()

void allocateBuffer ( int64_t numBytes )

protected

Allocates storage on the GPU for this buffer object.

Parameters

numBytes

Number of bytes to allocate.

setSubData()

template<typename... Ts>

void setSubData ( size_t offset, Utils::Span< Ts >... data )

protected

Upload data into the buffer starting at the given offset.

Parameters

offset	Offset in bytes into the buffer object's data store where start writing data.
data	Pack of data arrays that should be copied to the buffer. If you provide multiple spans they will be concatenated and end up next to each other in the buffer without any padding.

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

• ImFusion/Core/GL/Buffer.h