sf::VertexBuffer Class Reference

Vertex buffer storage for one or more 2D primitives. More...

#include <SFML/Graphics/VertexBuffer.hpp>

Inheritance diagram for sf::VertexBuffer:

Public Types
enum	Usage { Stream , Dynamic , Static }
	Usage specifiers. More...

Public Member Functions
	VertexBuffer ()
	Default constructor.
	VertexBuffer (PrimitiveType type)
	Construct a VertexBuffer with a specific PrimitiveType.
	VertexBuffer (Usage usage)
	Construct a VertexBuffer with a specific usage specifier.
	VertexBuffer (PrimitiveType type, Usage usage)
	Construct a VertexBuffer with a specific PrimitiveType and usage specifier.
	VertexBuffer (const VertexBuffer &copy)
	Copy constructor.
	~VertexBuffer ()
	Destructor.
bool	create (std::size_t vertexCount)
	Create the vertex buffer.
std::size_t	getVertexCount () const
	Return the vertex count.
bool	update (const Vertex *vertices)
	Update the whole buffer from an array of vertices.
bool	update (const Vertex *vertices, std::size_t vertexCount, unsigned int offset)
	Update a part of the buffer from an array of vertices.
bool	update (const VertexBuffer &vertexBuffer)
	Copy the contents of another buffer into this buffer.
VertexBuffer &	operator= (const VertexBuffer &right)
	Overload of assignment operator.
void	swap (VertexBuffer &right)
	Swap the contents of this vertex buffer with those of another.
unsigned int	getNativeHandle () const
	Get the underlying OpenGL handle of the vertex buffer.
void	setPrimitiveType (PrimitiveType type)
	Set the type of primitives to draw.
PrimitiveType	getPrimitiveType () const
	Get the type of primitives drawn by the vertex buffer.
void	setUsage (Usage usage)
	Set the usage specifier of this vertex buffer.
Usage	getUsage () const
	Get the usage specifier of this vertex buffer.

Static Public Member Functions
static void	bind (const VertexBuffer *vertexBuffer)
	Bind a vertex buffer for rendering.
static bool	isAvailable ()
	Tell whether or not the system supports vertex buffers.

Detailed Description

Vertex buffer storage for one or more 2D primitives.

sf::VertexBuffer is a simple wrapper around a dynamic buffer of vertices and a primitives type.

Unlike sf::VertexArray, the vertex data is stored in graphics memory.

In situations where a large amount of vertex data would have to be transferred from system memory to graphics memory every frame, using sf::VertexBuffer can help. By using a sf::VertexBuffer, data that has not been changed between frames does not have to be re-transferred from system to graphics memory as would be the case with sf::VertexArray. If data transfer is a bottleneck, this can lead to performance gains.

Using sf::VertexBuffer, the user also has the ability to only modify a portion of the buffer in graphics memory. This way, a large buffer can be allocated at the start of the application and only the applicable portions of it need to be updated during the course of the application. This allows the user to take full control of data transfers between system and graphics memory if they need to.

In special cases, the user can make use of multiple threads to update vertex data in multiple distinct regions of the buffer simultaneously. This might make sense when e.g. the position of multiple objects has to be recalculated very frequently. The computation load can be spread across multiple threads as long as there are no other data dependencies.

Simultaneous updates to the vertex buffer are not guaranteed to be carried out by the driver in any specific order. Updating the same region of the buffer from multiple threads will not cause undefined behaviour, however the final state of the buffer will be unpredictable.

Simultaneous updates of distinct non-overlapping regions of the buffer are also not guaranteed to complete in a specific order. However, in this case the user can make sure to synchronize the writer threads at well-defined points in their code. The driver will make sure that all pending data transfers complete before the vertex buffer is sourced by the rendering pipeline.

It inherits sf::Drawable, but unlike other drawables it is not transformable.

Example:

sf::Vertex vertices[15];
...
sf::VertexBuffer triangles(sf::Triangles);
triangles.create(15);
triangles.update(vertices);
...
window.draw(triangles);

See also

sf::Vertex, sf::VertexArray

Definition at line 46 of file VertexBuffer.hpp.

Member Enumeration Documentation

Usage

enum sf::VertexBuffer::Usage

Usage specifiers.

If data is going to be updated once or more every frame, set the usage to Stream. If data is going to be set once and used for a long time without being modified, set the usage to Static. For everything else Dynamic should be a good compromise.

Enumerator
Stream	Constantly changing data.
Dynamic	Occasionally changing data.
Static	Rarely changing data.

Definition at line 60 of file VertexBuffer.hpp.

Constructor & Destructor Documentation

VertexBuffer() [1/5]

sf::VertexBuffer::VertexBuffer

(

)

Default constructor.

Creates an empty vertex buffer.

VertexBuffer() [2/5]

sf::VertexBuffer::VertexBuffer ( PrimitiveType  type )

explicit

Construct a VertexBuffer with a specific PrimitiveType.

Creates an empty vertex buffer and sets its primitive type to type.

Parameters

type	Type of primitive

VertexBuffer() [3/5]

sf::VertexBuffer::VertexBuffer ( Usage  usage )

explicit

Construct a VertexBuffer with a specific usage specifier.

Creates an empty vertex buffer and sets its usage to usage.

Parameters

usage

Usage specifier

VertexBuffer() [4/5]

sf::VertexBuffer::VertexBuffer	(	PrimitiveType	type,
		Usage	usage
	)

Construct a VertexBuffer with a specific PrimitiveType and usage specifier.

Creates an empty vertex buffer and sets its primitive type to type and usage to usage.

Parameters

type	Type of primitive
usage	Usage specifier

VertexBuffer() [5/5]

sf::VertexBuffer::VertexBuffer

(

const VertexBuffer &

copy

)

Copy constructor.

Parameters

copy	instance to copy

~VertexBuffer()

sf::VertexBuffer::~VertexBuffer

(

)

Destructor.

Member Function Documentation

bind()

static void sf::VertexBuffer::bind ( const VertexBuffer *  vertexBuffer )

static

Bind a vertex buffer for rendering.

This function is not part of the graphics API, it mustn't be used when drawing SFML entities. It must be used only if you mix sf::VertexBuffer with OpenGL code.

sf::VertexBuffer vb1, vb2;
...
sf::VertexBuffer::bind(&vb1);
// draw OpenGL stuff that use vb1...
sf::VertexBuffer::bind(&vb2);
// draw OpenGL stuff that use vb2...
sf::VertexBuffer::bind(NULL);
// draw OpenGL stuff that use no vertex buffer...

Parameters

vertexBuffer

Pointer to the vertex buffer to bind, can be null to use no vertex buffer

create()

bool sf::VertexBuffer::create

(

std::size_t

vertexCount

)

Create the vertex buffer.

Creates the vertex buffer and allocates enough graphics memory to hold vertexCount vertices. Any previously allocated memory is freed in the process.

In order to deallocate previously allocated memory pass 0 as vertexCount. Don't forget to recreate with a non-zero value when graphics memory should be allocated again.

Parameters

vertexCount

Number of vertices worth of memory to allocate

Returns

True if creation was successful

getNativeHandle()

unsigned int sf::VertexBuffer::getNativeHandle

(

)

const

Get the underlying OpenGL handle of the vertex buffer.

You shouldn't need to use this function, unless you have very specific stuff to implement that SFML doesn't support, or implement a temporary workaround until a bug is fixed.

Returns

OpenGL handle of the vertex buffer or 0 if not yet created

getPrimitiveType()

PrimitiveType sf::VertexBuffer::getPrimitiveType

(

)

const

Get the type of primitives drawn by the vertex buffer.

Returns

Primitive type

getUsage()

Usage sf::VertexBuffer::getUsage

(

)

const

Get the usage specifier of this vertex buffer.

Returns

Usage specifier

getVertexCount()

std::size_t sf::VertexBuffer::getVertexCount

(

)

const

Return the vertex count.

Returns

Number of vertices in the vertex buffer

isAvailable()

static bool sf::VertexBuffer::isAvailable ( )

static

Tell whether or not the system supports vertex buffers.

This function should always be called before using the vertex buffer features. If it returns false, then any attempt to use sf::VertexBuffer will fail.

Returns

True if vertex buffers are supported, false otherwise

operator=()

VertexBuffer & sf::VertexBuffer::operator=

(

const VertexBuffer &

right

)

Overload of assignment operator.

Parameters

right

Instance to assign

Returns

Reference to self

setPrimitiveType()

void sf::VertexBuffer::setPrimitiveType

(

PrimitiveType

type

)

Set the type of primitives to draw.

This function defines how the vertices must be interpreted when it's time to draw them.

The default primitive type is sf::Points.

Parameters

type	Type of primitive

setUsage()

void sf::VertexBuffer::setUsage

(

Usage

usage

)

Set the usage specifier of this vertex buffer.

This function provides a hint about how this vertex buffer is going to be used in terms of data update frequency.

After changing the usage specifier, the vertex buffer has to be updated with new data for the usage specifier to take effect.

The default primitive type is sf::VertexBuffer::Stream.

Parameters

usage

Usage specifier

swap()

void sf::VertexBuffer::swap

(

VertexBuffer &

right

)

Swap the contents of this vertex buffer with those of another.

Parameters

right

Instance to swap with

update() [1/3]

bool sf::VertexBuffer::update

(

const Vertex *

vertices

)

Update the whole buffer from an array of vertices.

The vertex array is assumed to have the same size as the created buffer.

No additional check is performed on the size of the vertex array, passing invalid arguments will lead to undefined behavior.

This function does nothing if vertices is null or if the buffer was not previously created.

Parameters

vertices

Array of vertices to copy to the buffer

Returns

True if the update was successful

update() [2/3]

bool sf::VertexBuffer::update	(	const Vertex *	vertices,
		std::size_t	vertexCount,
		unsigned int	offset
	)

Update a part of the buffer from an array of vertices.

offset is specified as the number of vertices to skip from the beginning of the buffer.

If offset is 0 and vertexCount is equal to the size of the currently created buffer, its whole contents are replaced.

If offset is 0 and vertexCount is greater than the size of the currently created buffer, a new buffer is created containing the vertex data.

If offset is 0 and vertexCount is less than the size of the currently created buffer, only the corresponding region is updated.

If offset is not 0 and offset + vertexCount is greater than the size of the currently created buffer, the update fails.

No additional check is performed on the size of the vertex array, passing invalid arguments will lead to undefined behavior.

Parameters

vertices	Array of vertices to copy to the buffer
vertexCount	Number of vertices to copy
offset	Offset in the buffer to copy to

Returns

True if the update was successful

update() [3/3]

bool sf::VertexBuffer::update

(

const VertexBuffer &

vertexBuffer

)

Copy the contents of another buffer into this buffer.

Parameters

vertexBuffer

Vertex buffer whose contents to copy into this vertex buffer

Returns

True if the copy was successful

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

• VertexBuffer.hpp