Base class for OpenGL buffer objects, which are the building blocks of Vertex Buffer Objects. More...

#include <ocean/GLvish/BufferArray.hpp>

Inheritance diagram for Wizt::BufferArray:

Classes
struct	Error
	Exception class that might happen during loading of buffer arrays. More...

struct	Inconsistency
	Exception class thrown when an array of incompatible number of elements is going to be added to a given VBO object. More...

class	MapMemory
	API For glMapBuffer. More...

Public Types
enum	type
	Possible types of buffer ID's. More...

enum	usage
	Specifies the expected usage pattern of the data store. More...

Public Types inherited from MemCore::ReferenceBase< Tentacle >
using	reference_domain_t = Tentacle
	The type of the base class.

using	SelfPtr_t = WeakPtr< Tentacle, Tentacle >
	Type for a pointer to this object itself.

Public Member Functions
	BufferArray (type buffer_target, int AttributeClass=0)
	Construct an OpenGL buffer object (this call does NOT require an OpenGL Context)

virtual size_t	getComponentSize () const =0
	Get size of a component in bytes.

virtual size_t	getElementSize () const =0
	Return size of the type used for loading the data.

GLuint	getId () const noexcept
	Get an Id without attempting to generate it.

GLsizei	getStride () const
	A future version may use a stride that is shared among Buffers.

bool	isIndexBuffer () const
	Check whether this is an index buffer.

bool	isVertexArray () const
	Check whether this is a vertex array.

template<class Type >
bool	load_typed (const ::std::vector< Type > &data, size_t start, size_t end)
	Load subset of data from a Standard Template Vector.

template<class Type >
bool	load_typed (const ::std::vector< Type > &data, usage usage_hint=STATIC_DRAW)
	Load data from a Standard Template Vector.

size_t	memsize () const
	Return the memory occupied by this buffer.

size_t	NumberOfElements () const
	Returns the number of elements referenced via this BufferArray.

	~BufferArray ()
	Destructor - MUST be called within an OpenGL Context.

Public Member Functions inherited from Wizt::Anemone::Tentacle
virtual bool	activate (const Anemone &)=0
	Activate this tentacle.

virtual bool	deactivate (const Anemone &)=0
	Deactivate this tentacle.

virtual const char *	getSamplerType () const
	If this tentacle refers to some texture sampler in a shader, then hereby return the type of this sampler is it occurs in the code.

virtual int	getTextureUnit () const
	Get the texture unit number which was specified during construction, if positive then it refers to some texture unit that is used in an associated shader.

virtual bool	updateValue (VRenderContext &Context)
	Possibly update a tentacle from settings in a context.

Public Member Functions inherited from MemCore::ReferenceBase< Tentacle >
auto	getObjectCountID () const noexcept
	Get a unique ID for this object in the given domain.

bool	isIdentical (const WeakPtr< Tentacle, Tentacle > &PossibleSelf) const noexcept
	Check if this object is identical to the one used by the given pointer.

void	mkAutoDestructive ()
	Marks this object as being automatically destructed, e.g.

refcount_t	refcount () const noexcept
	The strong reference count.

	ReferenceBase (Tentacle *that) noexcept
	Constructor, initializes reference counter to zero.

const auto &	self () const
	Return weak pointer to the object self.

refcount_t	wrefcount () const noexcept
	The weak reference count.

Protected Member Functions
bool	load_subset (int offset, const void *ptr, memsize_t sz) const
	Load a subset of the data on the graphics card, updating an existing buffer.

bool	load_untyped (const void *ptr, memsize_t MemorySize, size_t nElements, usage usage_hint=STATIC_DRAW)
	Loads the given data on the graphix card.

Protected Member Functions inherited from MemCore::ReferenceBase< Tentacle >
virtual void	extremeUnction ()
	A virtual function that will be called just before the object is destroyed.

ReferenceBase &	operator= (const ReferenceBase &R)
	Protected assignment operator (should not be called).

void	suicide ()
	Delete this.

virtual	~ReferenceBase ()
	Virtual destructor.

Protected Member Functions inherited from Wizt::BufferID
bool	bindBuffer () const
	const version of bind(), does not create a buffer ID.

bool	bindBufferWithPossibleCreation ()
	Non-const version of bind().

	BufferID (const type bufferType) noexcept
	The constructor does not yet create openGL buffers yet.

GLuint	createId () noexcept
	If no valid ID yet, call glCreateBuffers().

GLuint	getId () const noexcept
	Get an Id without attempting to generate it.

bool	isbound () const throw ()
	Verification function: buffer is bound?

bool	isIndexBuffer () const
	Check whether this is an index buffer.

bool	isVertexArray () const
	Check whether this is a vertex array.

GLuint	makeId ()
	On first access, OpenGL buffers will be generated. This function must be called from within a valid OpenGL context.

GLuint	operator() ()
	On first access, OpenGL buffers will be generated. This function must be called from within a valid OpenGL context.

	~BufferID () noexcept
	Deletion of created OpenGL buffers. Note that this might be problematic here if called outside a valid OpenGL context.

Additional Inherited Members
Public Attributes inherited from Wizt::RenderBasin::VertexAttribute
unsigned	DoublePrecision:1
	Load data in double precision.

unsigned	Integer:1
	Hint whether the attribute is an integer data type in the shader, in which case it will be loaded differently.

unsigned	Normalized:1
	Indicate whether this buffer will be normalized to the range [0,1] if it is an integer type loaded to a floating point attribute.

unsigned	Signed:1
	Indicate if this integer type is signed.

Public Attributes inherited from Wizt::Anemone::Tentacle
Activity_t	Activity
	A bit mask telling whether this tentacle should participate in the waving of an Anemone.

Protected Types inherited from Wizt::BufferID
enum	type
	Possible types of buffer ID's. More...

Protected Attributes inherited from Wizt::BufferID
const type	target
	The target type of this buffer ID.

Detailed Description

Base class for OpenGL buffer objects, which are the building blocks of Vertex Buffer Objects.

A possible exception-save usage scenario is via the activateVB() macro:

BufferArray&B;
 
        activateVB(B)
        {
                ... render code ..
        }

See also: http://www.songho.ca/opengl/gl_vbo.html

Todo:: Need to specify the skeleton in the Anemone to which this attribute refers to.

Member Enumeration Documentation

◆ type

enum Wizt::BufferID::type

Possible types of buffer ID's.

See also: http://www.opengl.org/wiki/Buffer_Object

◆ usage

enum Wizt::BufferArray::usage

Specifies the expected usage pattern of the data store.

STREAM The data store contents will be modified once and used at most a few times.
STATIC The data store contents will be modified once and used many times.
DYNAMIC The data store contents will be modified repeatedly and used many times.

The nature of access may be one of these:

DRAW The data store contents are modified by the application, and used as the source for GL drawing and image specification commands.
READ The data store contents are modified by reading data from the GL, and used to return that data when queried by the application.
COPY The data store contents are modified by reading data from the GL, and used as the source for GL drawing and image specification commands.

See also: http://www.opengl.org/sdk/docs/man/xhtml/glBufferData.xml

Constructor & Destructor Documentation

◆ ~BufferArray()

Wizt::BufferArray::~BufferArray ( )

Destructor - MUST be called within an OpenGL Context.

If called in an non-OpenGL context, segmentation faults in the OpenGL driver/library will most likely occur. The preferred way is to store BufferArray objects in a GLCache, but NOT in an user-defined structure. The GLCache is supposed to be destroyed by the application when the OpenGL Context is destroyed, which is NOT when the containing objects are destroyed. Rather it is when a windows is closed, but not yet the application.

This mechanism does require special care and is non-trivial.

References Wizt::GLContextChecker::invalidContext().

Member Function Documentation

◆ getId()

GLuint Wizt::BufferID::getId ( ) const

noexcept

Get an Id without attempting to generate it.

This function is safe to be called from a non-OpenGL context.

◆ load_subset()

bool Wizt::BufferArray::load_subset	(	int	offset,
		const void *	ptr,
		memsize_t	sz
	)		const

protected

Load a subset of the data on the graphics card, updating an existing buffer.

Calls glBufferSubData() . http://www.opengl.org/sdk/docs/man/xhtml/glBufferSubData.xml

When replacing the entire data store, consider using glBufferSubData rather than completely recreating the data store with glBufferData. This avoids the cost of reallocating the data store.

Consider using multiple buffer objects to avoid stalling the rendering pipeline during data store updates. If any rendering in the pipeline makes reference to data in the buffer object being updated by glBufferSubData, especially from the specific region being updated, that rendering must drain from the pipeline before the data store can be updated.

Clients must align data elements consistent with the requirements of the client platform, with an additional base-level requirement that an offset within a buffer to a datum comprising N bytes be a multiple of N.

References Wizt::BufferID::bindBuffer(), and Wizt::BufferID::target.

◆ load_untyped()

bool Wizt::BufferArray::load_untyped	(	const void *	ptr,
		memsize_t	MemorySize,
		size_t	nElements,
		usage	usage_hint = `STATIC_DRAW`
	)

protected

Loads the given data on the graphix card.

Binds the current target and calls glBufferData().

Parameters

MemorySize	How much memory will this call occupy on the GPU? This value will be used in conjunction with the GLCache.
nElements	How much elements will be used in this array? This value will be used to check the consistency of Vertex Buffer Arrays, if an array with different number of elements is added, then an Inconsistency exception will be thrown.

Note: Clients must align data elements consistent with the requirements of the client platform, with an additional base-level requirement that an offset within a buffer to a datum comprising N bytes be a multiple of N.

See also: http://www.opengl.org/sdk/docs/man/xhtml/glBufferData.xml

Todo:: Call does unbind() internally. Think if that is a problem and/or should be optimized.

References Wizt::BufferID::bindBuffer(), Wizt::BufferID::createId(), load_untyped(), Wizt::BufferID::makeId(), MemCore::Timer::secs(), and Wizt::BufferID::target.

Referenced by load_untyped().

◆ NumberOfElements()

size_t Wizt::BufferArray::NumberOfElements ( ) const

inlinevirtual

Returns the number of elements referenced via this BufferArray.

It will be zero at construction and only be set using a \i typed load() call.

Reimplemented from Wizt::Anemone::Tentacle.

Classes

Public Types

Public Member Functions

Protected Member Functions

Additional Inherited Members