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#include <QtOpenGL/qgl.h>

#include <QtOpenGL/private/qgl_p.h>

#include <QtOpenGL/private/qglextensions_p.h>

#include "qglbuffer.h"

QT_BEGIN_NAMESPACE

/*!

    \class QGLBuffer

    \brief The QGLBuffer class provides functions for creating and managing GL buffer objects.

    \since 4.7

    \ingroup painting-3D

    Buffer objects are created in the GL server so that the

    client application can avoid uploading vertices, indices,

    texture image data, etc every time they are needed.

*/

/*!

    \enum QGLBuffer::Type

    This enum defines the type of GL buffer object to create with QGLBuffer.

    \value VertexBuffer Vertex buffer object for use when specifying

           vertex arrays.

    \value IndexBuffer Index buffer object for use with \c{glDrawElements()}.

    \value PixelPackBuffer Pixel pack buffer object for reading pixel

           data from the GL server (for example, with \c{glReadPixels()}).

           Not supported under OpenGL/ES.

    \value PixelUnpackBuffer Pixel unpack buffer object for writing pixel

           data to the GL server (for example, with \c{glTexImage2D()}).

           Not supported under OpenGL/ES.

*/

/*!

    \enum QGLBuffer::UsagePattern

    This enum defines the usage pattern of a QGLBuffer object.

    \value StreamDraw The data will be set once and used a few times

           for drawing operations.  Under OpenGL/ES 1.1 this is identical

           to StaticDraw.

    \value StreamRead The data will be set once and used a few times

           for reading data back from the GL server.  Not supported

           under OpenGL/ES.

    \value StreamCopy The data will be set once and used a few times

           for reading data back from the GL server for use in further

           drawing operations.  Not supported under OpenGL/ES.

    \value StaticDraw The data will be set once and used many times

           for drawing operations.

    \value StaticRead The data will be set once and used many times

           for reading data back from the GL server.  Not supported

           under OpenGL/ES.

    \value StaticCopy The data will be set once and used many times

           for reading data back from the GL server for use in further

           drawing operations.  Not supported under OpenGL/ES.

    \value DynamicDraw The data will be modified repeatedly and used

           many times for drawing operations.

    \value DynamicRead The data will be modified repeatedly and used

           many times for reading data back from the GL server.

           Not supported under OpenGL/ES.

    \value DynamicCopy The data will be modified repeatedly and used

           many times for reading data back from the GL server for

           use in further drawing operations.  Not supported under OpenGL/ES.

*/

/*!

    \enum QGLBuffer::Access

    This enum defines the access mode for QGLBuffer::map().

    \value ReadOnly The buffer will be mapped for reading only.

    \value WriteOnly The buffer will be mapped for writing only.

    \value ReadWrite The buffer will be mapped for reading and writing.

*/

class QGLBufferPrivate

{

public:

    QGLBufferPrivate(QGLBuffer::Type t)

          guard(0),

          usagePattern(QGLBuffer::StaticDraw),

          actualUsagePattern(QGLBuffer::StaticDraw)

    {

    }

    QGLBuffer::Type type;

    QGLSharedResourceGuard guard;

    QGLBuffer::UsagePattern usagePattern;

    QGLBuffer::UsagePattern actualUsagePattern;

};

/*!

    Constructs a new buffer object of \a type.

    Note: this constructor just creates the QGLBuffer instance.  The actual

    buffer object in the GL server is not created until create() is called.

    \sa create()

*/

QGLBuffer::QGLBuffer(QGLBuffer::Type type)

    : d_ptr(new QGLBufferPrivate(type))

{

}

#define ctx d->guard.context()

/*!

    Destroys this buffer object, including the storage being

    used in the GL server.

*/

QGLBuffer::~QGLBuffer()

{

    }

}

/*!

    Returns the type of buffer represented by this object.

*/

QGLBuffer::Type QGLBuffer::type() const

{

    Q_D(const QGLBuffer);

    return d->type;

}

/*!

    Returns the usage pattern for this buffer object.

    The default value is StaticDraw.

    \sa setUsagePattern()

*/

QGLBuffer::UsagePattern QGLBuffer::usagePattern() const

{

    Q_D(const QGLBuffer);

    return d->usagePattern;

}

/*!

    Sets the usage pattern for this buffer object to \a value.

    This function must be called before allocate() or write().

    \sa usagePattern(), allocate(), write()

*/

void QGLBuffer::setUsagePattern(QGLBuffer::UsagePattern value)

{

    Q_D(QGLBuffer);

#if defined(QT_OPENGL_ES_1)

    // OpenGL/ES 1.1 does not support GL_STREAM_DRAW, so use GL_STATIC_DRAW.

    // OpenGL/ES 2.0 does support GL_STREAM_DRAW.

    d->usagePattern = value;

    if (value == StreamDraw)

        d->actualUsagePattern = StaticDraw;

    else

        d->actualUsagePattern = value;

#else

    d->usagePattern = d->actualUsagePattern = value;

#endif

}

#undef ctx

/*!

    Creates the buffer object in the GL server.  Returns true if

    the object was created; false otherwise.

    This function must be called with a current QGLContext.

    The buffer will be bound to and can only be used in

    that context (or any other context that is shared with it).

    This function will return false if the GL implementation

    does not support buffers, or there is no current QGLContext.

*/

bool QGLBuffer::create()

{

    Q_D(QGLBuffer);

    if (d->guard.id())

        return true;

    const QGLContext *ctx = QGLContext::currentContext();

    if (ctx) {

        if (!qt_resolve_buffer_extensions(const_cast<QGLContext *>(ctx)))

            return false;

        GLuint bufferId = 0;

        glGenBuffers(1, &bufferId);

        if (bufferId) {

            d->guard.setContext(ctx);

            d->guard.setId(bufferId);

            return true;

        }

    }

    return false;

}

#define ctx d->guard.context()

/*!

    Returns true if this buffer has been created; false otherwise.

*/

bool QGLBuffer::isCreated() const

{

    Q_D(const QGLBuffer);

    return d->guard.id() != 0;

}

/*!

    Reads the \a count bytes in this buffer starting at \a offset

    into \a data.  Returns true on success; false if reading from

    the buffer is not supported.  Buffer reading is not supported

    under OpenGL/ES.

    It is assumed that this buffer has been bound to the current context.

    \sa write(), bind()

*/

bool QGLBuffer::read(int offset, void *data, int count)

{

#if !defined(QT_OPENGL_ES)

    Q_D(QGLBuffer);

    if (!glGetBufferSubData || !d->guard.id())

        return false;

    while (glGetError() != GL_NO_ERROR) ; // Clear error state.

    glGetBufferSubData(d->type, offset, count, data);

    return glGetError() == GL_NO_ERROR;

#else

    Q_UNUSED(offset);

    Q_UNUSED(data);

    Q_UNUSED(count);

    return false;

#endif

}

/*!

    Replaces the \a count bytes of this buffer starting at \a offset

    with the contents of \a data.  Any other bytes in the buffer

    will be left unmodified.

    It is assumed that create() has been called on this buffer and that

    it has been bound to the current context.

    \sa create(), read(), allocate()

*/

void QGLBuffer::write(int offset, const void *data, int count)

{

#ifndef QT_NO_DEBUG

    if (!isCreated())

        qWarning("QGLBuffer::allocate(): buffer not created");

#endif

    Q_D(QGLBuffer);

    if (d->guard.id())

        glBufferSubData(d->type, offset, count, data);

}

/*!

    Allocates \a count bytes of space to the buffer, initialized to

    the contents of \a data.  Any previous contents will be removed.

    It is assumed that create() has been called on this buffer and that

    it has been bound to the current context.

    \sa create(), read(), write()

*/

void QGLBuffer::allocate(const void *data, int count)

{

#ifndef QT_NO_DEBUG

    if (!isCreated())

        qWarning("QGLBuffer::allocate(): buffer not created");

#endif

    Q_D(QGLBuffer);

    if (d->guard.id())

        glBufferData(d->type, count, data, d->actualUsagePattern);

}

/*!

    \fn void QGLBuffer::allocate(int count)

    \overload

    Allocates \a count bytes of space to the buffer.  Any previous

    contents will be removed.

    It is assumed that create() has been called on this buffer and that

    it has been bound to the current context.

    \sa create(), write()

*/

/*!

    Binds the buffer associated with this object to the current

    GL context.  Returns false if binding was not possible, usually because

    type() is not supported on this GL implementation.

    The buffer must be bound to the same QGLContext current when create()

    was called, or to another QGLContext that is sharing with it.

    Otherwise, false will be returned from this function.

    \sa release(), create()

*/

bool QGLBuffer::bind() const

{

#ifndef QT_NO_DEBUG

    if (!isCreated())

        qWarning("QGLBuffer::bind(): buffer not created");

#endif

    Q_D(const QGLBuffer);

    GLuint bufferId = d->guard.id();

    if (bufferId) {

        if (!QGLContext::areSharing(QGLContext::currentContext(),

                                    d->guard.context())) {

#ifndef QT_NO_DEBUG

            qWarning("QGLBuffer::bind: buffer is not valid in the current context");

#endif

            return false;

        }

        glBindBuffer(d->type, bufferId);

        return true;

    } else {

        return false;

    }

}

/*!

    Releases the buffer associated with this object from the

    current GL context.

    This function must be called with the same QGLContext current

    as when bind() was called on the buffer.

    \sa bind()

*/

void QGLBuffer::release() const

{

#ifndef QT_NO_DEBUG

    if (!isCreated())

        qWarning("QGLBuffer::release(): buffer not created");

#endif

    Q_D(const QGLBuffer);

    if (d->guard.id())

        glBindBuffer(d->type, 0);

}

#undef ctx

/*!

    Releases the buffer associated with \a type in the current

    QGLContext.

    This function is a direct call to \c{glBindBuffer(type, 0)}

    for use when the caller does not know which QGLBuffer has

    been bound to the context but wants to make sure that it

    is released.

    \code

    QGLBuffer::release(QGLBuffer::VertexBuffer);

    \endcode

*/

void QGLBuffer::release(QGLBuffer::Type type)

{

    const QGLContext *ctx = QGLContext::currentContext();

    if (ctx && qt_resolve_buffer_extensions(const_cast<QGLContext *>(ctx)))

        glBindBuffer(GLenum(type), 0);

}

#define ctx d->guard.context()

/*!

    Returns the GL identifier associated with this buffer; zero if

    the buffer has not been created.

    \sa isCreated()

*/

GLuint QGLBuffer::bufferId() const

{

    Q_D(const QGLBuffer);

    return d->guard.id();

}

#ifndef GL_BUFFER_SIZE

#define GL_BUFFER_SIZE 0x8764

#endif

/*!

    Returns the size of the data in this buffer, for reading operations.

    Returns -1 if fetching the buffer size is not supported, or the

    buffer has not been created.

    It is assumed that this buffer has been bound to the current context.

    \sa isCreated(), bind()

*/

int QGLBuffer::size() const

{

    Q_D(const QGLBuffer);

    if (!d->guard.id())

        return -1;

    GLint value = -1;

    glGetBufferParameteriv(d->type, GL_BUFFER_SIZE, &value);

    return value;

}

/*!