qsggeometry.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant reason:default
 
#include "qsggeometry.h"
#include "qsggeometry_p.h"
 
#ifdef Q_OS_QNX
#include <malloc.h>
#endif
 
QT_BEGIN_NAMESPACE
 
 
QSGGeometry::Attribute QSGGeometry::Attribute::create(int attributeIndex, int tupleSize, int primitiveType, bool isPrimitive)
{
    Attribute a = { attributeIndex, tupleSize, primitiveType, isPrimitive, UnknownAttribute, 0 };
    return a;
}
 
QSGGeometry::Attribute QSGGeometry::Attribute::createWithAttributeType(int pos, int tupleSize, int primitiveType, AttributeType attributeType)
{
    Attribute a;
    a.position = pos;
    a.tupleSize = tupleSize;
    a.type = primitiveType;
    a.isVertexCoordinate = attributeType == PositionAttribute;
    a.attributeType = attributeType;
    a.reserved = 0;
    return a;
}
 
/*!
    Convenience function which returns attributes to be used for 2D solid
    color drawing.
 */
 
const QSGGeometry::AttributeSet &QSGGeometry::defaultAttributes_Point2D()
{
    static Attribute data[] = {
        Attribute::createWithAttributeType(0, 2, FloatType, PositionAttribute)
    };
    static AttributeSet attrs = { 1, sizeof(float) * 2, data };
    return attrs;
}
 
/*!
    Convenience function which returns attributes to be used for textured 2D drawing.
 */
 
const QSGGeometry::AttributeSet &QSGGeometry::defaultAttributes_TexturedPoint2D()
{
    static Attribute data[] = {
        Attribute::createWithAttributeType(0, 2, FloatType, PositionAttribute),
        Attribute::createWithAttributeType(1, 2, FloatType, TexCoordAttribute)
    };
    static AttributeSet attrs = { 2, sizeof(float) * 4, data };
    return attrs;
}
 
/*!
    Convenience function which returns attributes to be used for per vertex colored 2D drawing.
 */
 
const QSGGeometry::AttributeSet &QSGGeometry::defaultAttributes_ColoredPoint2D()
{
    static Attribute data[] = {
        Attribute::createWithAttributeType(0, 2, FloatType, PositionAttribute),
        Attribute::createWithAttributeType(1, 4, UnsignedByteType, ColorAttribute)
    };
    static AttributeSet attrs = { 2, 2 * sizeof(float) + 4 * sizeof(char), data };
    return attrs;
}
 
 
/*!
    \class QSGGeometry::Attribute
    \brief The QSGGeometry::Attribute describes a single vertex attribute in a QSGGeometry.
    \inmodule QtQuick
 
    The QSGGeometry::Attribute struct describes the attribute register position,
    the size of the attribute tuple and the attribute type.
 
    It also contains a hint to the renderer if this attribute is the attribute
    describing the position. The scene graph renderer may use this information
    to perform optimizations.
 
    It contains a number of bits which are reserved for future use.
 
    \sa QSGGeometry
 */
 
/*!
    \fn QSGGeometry::Attribute QSGGeometry::Attribute::create(int pos, int tupleSize, int primitiveType, bool isPosition)
 
    Creates a new QSGGeometry::Attribute for attribute register \a pos with \a
    tupleSize. The \a primitiveType can be any of the supported types from
    QSGGeometry::Type, such as QSGGeometry::FloatType or
    QSGGeometry::UnsignedByteType.
 
    If the attribute describes the position for the vertex, the \a isPosition
    hint should be set to \c true. The scene graph renderer may use this
    information to perform optimizations.
 
    Use the create function to construct the attribute, rather than an
    initialization list, to ensure that all fields are initialized.
 */
 
/*!
    \fn QSGGeometry::Attribute QSGGeometry::Attribute::createWithAttributeType(int pos, int tupleSize, int primitiveType, AttributeType attributeType)
 
    Creates a new QSGGeometry::Attribute for attribute register \a pos with \a
    tupleSize. The \a primitiveType can be any of the supported types from
    QSGGeometry::Type, such as QSGGeometry::FloatType or
    QSGGeometry::UnsignedByteType.
 
    \a attributeType describes the intended use of the attribute.
 
    Use the create function to construct the attribute, rather than an
    initialization list, to ensure that all fields are initialized.
 */
 
 
/*!
    \class QSGGeometry::AttributeSet
    \brief The QSGGeometry::AttributeSet describes how the vertices in a QSGGeometry
    are built up.
    \inmodule QtQuick
 
    \sa QSGGeometry
 */
 
 
/*!
   \class QSGGeometry::Point2D
   \brief The QSGGeometry::Point2D struct is a convenience struct for accessing
   2D Points.
 
   \inmodule QtQuick
 */
 
 
/*!
   \fn void QSGGeometry::Point2D::set(float x, float y)
 
   Sets the x and y values of this point to \a x and \a y.
 */
 
 
/*!
   \class QSGGeometry::ColoredPoint2D
   \brief The QSGGeometry::ColoredPoint2D struct is a convenience struct for accessing
   2D Points with a color.
 
   \inmodule QtQuick
 */
 
 
/*!
   \fn void QSGGeometry::ColoredPoint2D::set(float x, float y, uchar red, uchar green, uchar blue, uchar alpha)
 
   Sets the position of the vertex to \a x and \a y and the color to \a red, \a
   green, \a blue, and \a alpha.
 */
 
 
/*!
   \class QSGGeometry::TexturedPoint2D
   \brief The QSGGeometry::TexturedPoint2D struct is a convenience struct for accessing
   2D Points with texture coordinates.
 
   \inmodule QtQuick
 */
 
 
/*!
   \fn void QSGGeometry::TexturedPoint2D::set(float x, float y, float tx, float ty)
 
   Sets the position of the vertex to \a x and \a y and the texture coordinate
   to \a tx and \a ty.
 */
 
 
 
/*!
    \class QSGGeometry
 
    \brief The QSGGeometry class provides low-level
    storage for graphics primitives in the \l{Qt Quick Scene Graph}.
 
    \inmodule QtQuick
 
    The QSGGeometry class stores the geometry of the primitives rendered
    with the scene graph. It contains vertex data and optionally index
    data. The mode used to draw the geometry, also called primitive
    topology, is specified with setDrawingMode().
 
    Vertices can be as simple as points defined by x and y values or
    can be more complex where each vertex contains a normal, texture
    coordinates and a 3D position. The QSGGeometry::AttributeSet is
    used to describe how the vertex data is built up. The attribute
    set can only be specified on construction.  The QSGGeometry class
    provides a few convenience attributes and attribute sets by
    default. The defaultAttributes_Point2D() function returns an
    attribute set to be used in normal solid color rectangles, while
    the defaultAttributes_TexturedPoint2D function returns attributes
    to be used for textured 2D geometry. The vertex data is internally
    stored as a \c {void *} and is accessible with the vertexData()
    function. Convenience accessors for the common attribute sets are
    available with vertexDataAsPoint2D() and
    vertexDataAsTexturedPoint2D(). Vertex data is allocated by passing
    a vertex count to the constructor or by calling allocate() later.
 
    The number of vertices and indices can be changed after construction
    by using the allocate() method to resize the data buffer. However,
    allocate() requires updating all vertex and index data each time
    called. Since Qt 6.10, setVertexCount() and setIndexCount() allow
    adjusting the number of vertices or indices without reallocating the
    data buffer and only require updating new vertices or indices. In
    either case, the caller must mark the geometry node as dirty, by calling
    \c{node->markDirty(QSGNode::DirtyGeometry)}, to ensure that the renderer
    has a chance to update internal buffers.
 
    The QSGGeometry can optionally contain indices of either unsigned
    32-bit, unsigned 16-bit, or unsigned 8-bit integers. The index type
    must be specified during construction and cannot be changed.
 
    Below is a snippet illustrating how a geometry composed of
    position and color vertices can be built.
 
    \code
    struct MyPoint2D {
        float x;
        float y;
        float r;
        float g;
        float b;
        float a;
 
        void set(float x_, float y_, float r_, float g_, float b_, float a_) {
            x = x_;
            y = y_;
            r = r_;
            g = g_;
            b = b_;
            a = a_;
        }
    };
 
    QSGGeometry::Attribute MyPoint2D_Attributes[] = {
        QSGGeometry::Attribute::create(0, 2, FloatType, true),
        QSGGeometry::Attribute::create(1, 4, FloatType, false)
    };
 
    QSGGeometry::AttributeSet MyPoint2D_AttributeSet = {
        2,
        sizeof(MyPoint2D),
        MyPoint2D_Attributes
    };
 
    ...
 
    geometry = new QSGGeometry(MyPoint2D_AttributeSet, 2);
    geometry->setDrawingMode(DrawLines);
 
    MyPoint2D *vertices = static_cast<MyPoint2D *>(geometry->vertexData());
    vertices[0].set(0, 0, 1, 0, 0, 1);
    vertices[1].set(width(), height(), 0, 0, 1, 1);
    \endcode
 
    The QSGGeometry is a software buffer and client-side in terms of
    accelerated rendering, as the buffers used in 2D graphics typically consist of
    many small buffers that change every frame and do not benefit from
    being uploaded to graphics memory. However, the QSGGeometry
    supports hinting to the renderer that a buffer should be
    uploaded using the setVertexDataPattern() and
    setIndexDataPattern() functions. Whether this hint is respected or
    not is implementation specific.
 
    \sa QSGGeometryNode, {Scene Graph - Custom Geometry}
 
    \note All classes with QSG prefix should be used solely on the scene graph's
    rendering thread. See \l {Scene Graph and Rendering} for more information.
 
 */
 
/*!
    \fn int QSGGeometry::attributeCount() const
 
    Returns the number of attributes in the attrbute set used by this geometry.
 */
 
/*!
    \fn QSGGeometry::Attribute *QSGGeometry::attributes() const
 
    Returns an array with the attributes of this geometry. The size of the array
    is given with attributeCount().
 */
 
/*!
    \fn uint *QSGGeometry::indexDataAsUInt()
 
    Convenience function to access the index data as a mutable array of
    32-bit unsigned integers.
 */
 
/*!
    \fn const uint *QSGGeometry::indexDataAsUInt() const
 
    Convenience function to access the index data as an immutable array of
    32-bit unsigned integers.
 */
 
/*!
    \fn quint16 *QSGGeometry::indexDataAsUShort()
 
    Convenience function to access the index data as a mutable array of
    16-bit unsigned integers.
 */
 
/*!
    \fn const quint16 *QSGGeometry::indexDataAsUShort() const
 
    Convenience function to access the index data as an immutable array of
    16-bit unsigned integers.
 */
 
/*!
    \fn const QSGGeometry::ColoredPoint2D *QSGGeometry::vertexDataAsColoredPoint2D() const
 
    Convenience function to access the vertex data as an immutable
    array of QSGGeometry::ColoredPoint2D.
 */
 
/*!
    \fn QSGGeometry::ColoredPoint2D *QSGGeometry::vertexDataAsColoredPoint2D()
 
    Convenience function to access the vertex data as a mutable
    array of QSGGeometry::ColoredPoint2D.
 */
 
/*!
    \fn const QSGGeometry::TexturedPoint2D *QSGGeometry::vertexDataAsTexturedPoint2D() const
 
    Convenience function to access the vertex data as an immutable
    array of QSGGeometry::TexturedPoint2D.
 */
 
/*!
    \fn QSGGeometry::TexturedPoint2D *QSGGeometry::vertexDataAsTexturedPoint2D()
 
    Convenience function to access the vertex data as a mutable
    array of QSGGeometry::TexturedPoint2D.
 */
 
/*!
    \fn const QSGGeometry::Point2D *QSGGeometry::vertexDataAsPoint2D() const
 
    Convenience function to access the vertex data as an immutable
    array of QSGGeometry::Point2D.
 */
 
/*!
    \fn QSGGeometry::Point2D *QSGGeometry::vertexDataAsPoint2D()
 
    Convenience function to access the vertex data as a mutable
    array of QSGGeometry::Point2D.
 */
 
 
/*!
    Constructs a geometry object based on \a attributes.
 
    The object allocate space for \a vertexCount vertices based on the
    accumulated size in \a attributes and for \a indexCount.
 
    The \a indexType can be UnsignedShortType or \c
    UnsignedIntType. Support for the latter depends on the graphics API
    implementation used at run time, and may not always be available.
 
    Geometry objects are constructed by default with DrawTriangleStrip as
    the drawing mode.
 
    \note \a attributes and the \l Attribute objects referenced by it must
          stay valid for the entire lifetime of the QSGGeometry.
          QSGGeometry stores a reference to \a attributes and does not delete
          the \l Attribute objects.
 */
 
QSGGeometry::QSGGeometry(const QSGGeometry::AttributeSet &attributes,
                         int vertexCount,
                         int indexCount,
                         int indexType)
    : m_drawing_mode(DrawTriangleStrip)
    , m_vertex_count(0)
    , m_index_count(0)
    , m_index_type(indexType)
    , m_attributes(attributes)
    , m_data(nullptr)
    , m_index_data_offset(-1)
    , m_server_data(nullptr)
    , m_owns_data(false)
    , m_index_usage_pattern(AlwaysUploadPattern)
    , m_vertex_usage_pattern(AlwaysUploadPattern)
    , m_line_width(1.0)
{
    Q_UNUSED(m_reserved_bits);
    Q_ASSERT(m_attributes.count > 0);
    Q_ASSERT(m_attributes.stride > 0);
    if (indexType != UnsignedByteType
        && indexType != UnsignedShortType
        && indexType != UnsignedIntType) {
        qFatal("QSGGeometry: Unsupported index type, %x.\n", indexType);
    }
 
    // Because allocate reads m_vertex_count, m_index_count and m_owns_data, these
    // need to be set before calling allocate...
    allocate(vertexCount, indexCount);
}
 
/*!
    \fn int QSGGeometry::sizeOfVertex() const
 
    Returns the size in bytes of one vertex.
 
    This value comes from the attributes.
 */
 
/*!
    \fn int QSGGeometry::sizeOfIndex() const
 
    Returns the byte size of the index type.
 
    This value is either \c 2 when the index type is UnsignedShortType, or
    \c 4 when the index type is UnsignedIntType.
 */
 
/*!
    Destroys the geometry object and the vertex and index data it has allocated.
 */
 
QSGGeometry::~QSGGeometry()
{
    if (m_owns_data)
        free(m_data);
 
    if (m_server_data)
        delete m_server_data;
}
 
/*!
    \fn int QSGGeometry::vertexCount() const
 
    Returns the number of vertices that can be rendered, or if indices are used,
    it returns the number of vertices that can be accessed through indices.
 
    \sa setVertexCount()
 */
 
/*!
    Sets the number of vertices to be rendered.
 
    The \a count is not validated and it is the users responsibility to ensure
    that only values between zero and the number of allocated vertices are
    specified.
 
    Vertex data is not invalidated after this call, but the caller must mark
    the geometry node as dirty, by calling \c{node->markDirty(QSGNode::DirtyGeometry)},
    to ensure that the renderer has a chance to update internal buffers.
 
    \since 6.10
 
    \sa vertexCount()
 */
void QSGGeometry::setVertexCount(int count)
{
    m_vertex_count = count;
}
 
 
/*!
    \fn int QSGGeometry::indexCount() const
 
    Returns the number of indices that are processed when the geometry object
    is rendered.
 
    \sa setIndexCount()
 */
 
/*!
    Sets the number of indices to be processed each time the geometry object is
    rendered.
 
    The \a count is not validated and it is the users responsibility to ensure
    that only values between zero and the number of allocated indices are
    specified.
 
    Vertex and index data is not invalidated after this call, but the caller must
    mark the geometry node as dirty, by calling \c{node->markDirty(QSGNode::DirtyGeometry)},
    to ensure that the renderer has a chance to update internal buffers.
 
    \since 6.10
 
    \sa indexCount()
 */
void QSGGeometry::setIndexCount(int count)
{
    m_index_count = count;
}
 
 
/*!
    \fn void *QSGGeometry::vertexData()
 
    Returns a pointer to the raw vertex data of this geometry object.
 
    \sa vertexDataAsPoint2D(), vertexDataAsTexturedPoint2D()
 */
 
/*!
    \fn const void *QSGGeometry::vertexData() const
 
    Returns a pointer to the raw vertex data of this geometry object.
 
    \sa vertexDataAsPoint2D(), vertexDataAsTexturedPoint2D()
 */
 
/*!
    Returns a pointer to the raw index data of this geometry object.
 
    \sa indexDataAsUShort(), indexDataAsUInt()
 */
void *QSGGeometry::indexData()
{
    return m_index_data_offset < 0
            ? nullptr
            : ((char *) m_data + m_index_data_offset);
}
 
/*!
    Returns a pointer to the raw index data of this geometry object.
 
    \sa indexDataAsUShort(), indexDataAsUInt()
 */
const void *QSGGeometry::indexData() const
{
    return m_index_data_offset < 0
            ? nullptr
            : ((char *) m_data + m_index_data_offset);
}
 
/*!
    \enum QSGGeometry::DrawingMode
 
    Specifies the drawing mode, also called primitive topology.
 
    \note Starting with Qt 6 the scene graph only exposes topologies that are
    supported across all the supported 3D graphics APIs. As a result, the
    values \c DrawLineLoop and \c DrawTriangleFan are no longer supported at
    run time in Qt 6, even though the enum values themselves are still present.
 
    \value DrawPoints
    \value DrawLines
    \omitvalue DrawLineLoop
    \value DrawLineStrip
    \value DrawTriangles
    \value DrawTriangleStrip
    \omitvalue DrawTriangleFan
 */
 
/*!
    \enum QSGGeometry::Type
 
    Specifies the component type in the vertex data.
 
    \value ByteType
    \value UnsignedByteType
    \value ShortType
    \value UnsignedShortType
    \value IntType
    \value UnsignedIntType
    \value FloatType
    \value Bytes2Type Added in Qt 5.14.
    \value Bytes3Type Added in Qt 5.14.
    \value Bytes4Type Added in Qt 5.14.
    \value DoubleType Added in Qt 5.14.
 */
 
/*!
    Sets the \a mode to be used for drawing this geometry.
 
    The default value is QSGGeometry::DrawTriangleStrip.
 
    \sa DrawingMode
 */
void QSGGeometry::setDrawingMode(unsigned int mode)
{
    m_drawing_mode = mode;
}
 
/*!
    Gets the current line or point width or to be used for this geometry. This
    property only applies to line width when the drawingMode is DrawLines or
    DrawLineStrip. When supported, it also applies to point size when the
    drawingMode is DrawPoints.
 
    The default value is \c 1.0
 
    \note Support for point and line drawing may be limited at run time,
    depending on the platform and graphics API. For example, some APIs do
    not support point sprites and so setting a size other than 1 is not
    possible.
 
    \note The width of \c 1.0 is always supported.
 
    \sa setLineWidth(), drawingMode()
 */
float QSGGeometry::lineWidth() const
{
    return m_line_width;
}
 
/*!
    Sets the line or point width to be used for this geometry to \a width. This
    property only applies to line width when the drawingMode is DrawLines or
    DrawLineStrip. When supported, it also applies to point size when the
    drawingMode is DrawPoints.
 
    \note Support for point and line drawing may be limited at run time,
    depending on the platform and graphics API. For example, some APIs do
    not support point sprites and so setting a size other than 1 is not
    possible.
 
    \note The width of \c 1.0 is always supported.
 
    \sa lineWidth(), drawingMode()
 */
void QSGGeometry::setLineWidth(float width)
{
    m_line_width = width;
}
 
/*!
    \fn int QSGGeometry::drawingMode() const
 
    Returns the drawing mode of this geometry.
 
    The default value is DrawTriangleStrip.
 */
 
/*!
    \fn int QSGGeometry::indexType() const
 
    Returns the primitive type used for indices in this
    geometry object.
 */
 
 
/*!
    Resizes the vertex and index data of this geometry object to fit \a vertexCount
    vertices and \a indexCount indices and sets the number of vertices and
    indices accordingly.
 
    Use setVertexCount() or setIndexCount() to change the number of vertices
    or indices without calling allocate() again.
 
    Vertex and index data will be invalidated after this call and the caller must
    mark the associated geometry node as dirty, by calling
    \c{node->markDirty(QSGNode::DirtyGeometry)}, to ensure that the renderer has
    a chance to update internal buffers.
 
    \sa setVertexCount(), setIndexCount()
 */
void QSGGeometry::allocate(int vertexCount, int indexCount)
{
    if (vertexCount == m_vertex_count && indexCount == m_index_count)
        return;
 
    m_vertex_count = vertexCount;
    m_index_count = indexCount;
 
    bool canUsePrealloc = m_index_count <= 0;
    int vertexByteSize = m_attributes.stride * m_vertex_count;
 
    if (m_owns_data)
        free(m_data);
 
    if (canUsePrealloc && vertexByteSize <= (int) sizeof(m_prealloc)) {
        // The preallocated buffer is suitable for simple geometry objects like
        // rectangles and avoids a malloc/free but does not support index data.
        m_data = (void *) &m_prealloc[0];
        m_index_data_offset = -1;
        m_owns_data = false;
    } else {
        Q_ASSERT(m_index_type == UnsignedIntType || m_index_type == UnsignedShortType);
        int indexByteSize = indexCount * (m_index_type == UnsignedShortType ? sizeof(quint16) : sizeof(quint32));
        m_data = (void *) malloc(vertexByteSize + indexByteSize);
        Q_CHECK_PTR(m_data);
        m_index_data_offset = vertexByteSize;
        m_owns_data = true;
    }
 
    // If we have associated vbo data we could potentially crash later if
    // the old buffers are used with the new vertex and index count, so we force
    // an update in the renderer in that case. This is really the users responsibility
    // but it is cheap for us to enforce this, so why not...
    if (m_server_data) {
        markIndexDataDirty();
        markVertexDataDirty();
    }
}
 
/*!
    Updates the geometry \a g with the coordinates in \a rect.
 
    The function assumes the geometry object contains a single triangle strip
    of QSGGeometry::Point2D vertices
 */
void QSGGeometry::updateRectGeometry(QSGGeometry *g, const QRectF &rect)
{
    Point2D *v = g->vertexDataAsPoint2D();
    v[0].x = rect.left();
    v[0].y = rect.top();
 
    v[1].x = rect.left();
    v[1].y = rect.bottom();
 
    v[2].x = rect.right();
    v[2].y = rect.top();
 
    v[3].x = rect.right();
    v[3].y = rect.bottom();
}
 
/*!
    Updates the geometry \a g with the coordinates in \a rect and texture
    coordinates from \a textureRect.
 
    \a textureRect should be in normalized coordinates.
 
    \a g is assumed to be a triangle strip of four vertices of type
    QSGGeometry::TexturedPoint2D.
 */
void QSGGeometry::updateTexturedRectGeometry(QSGGeometry *g, const QRectF &rect, const QRectF &textureRect)
{
    TexturedPoint2D *v = g->vertexDataAsTexturedPoint2D();
    v[0].x = rect.left();
    v[0].y = rect.top();
    v[0].tx = textureRect.left();
    v[0].ty = textureRect.top();
 
    v[1].x = rect.left();
    v[1].y = rect.bottom();
    v[1].tx = textureRect.left();
    v[1].ty = textureRect.bottom();
 
    v[2].x = rect.right();
    v[2].y = rect.top();
    v[2].tx = textureRect.right();
    v[2].ty = textureRect.top();
 
    v[3].x = rect.right();
    v[3].y = rect.bottom();
    v[3].tx = textureRect.right();
    v[3].ty = textureRect.bottom();
}
 
/*!
    Updates the geometry \a g with the coordinates in \a rect.
 
    The function assumes the geometry object contains a single triangle strip
    of QSGGeometry::ColoredPoint2D vertices
 */
void QSGGeometry::updateColoredRectGeometry(QSGGeometry *g, const QRectF &rect)
{
    ColoredPoint2D *v = g->vertexDataAsColoredPoint2D();
    v[0].x = rect.left();
    v[0].y = rect.top();
 
    v[1].x = rect.left();
    v[1].y = rect.bottom();
 
    v[2].x = rect.right();
    v[2].y = rect.top();
 
    v[3].x = rect.right();
    v[3].y = rect.bottom();
}
 
/*!
  \enum QSGGeometry::AttributeType
 
  This enum identifies several attribute types.
 
  \value UnknownAttribute    Don't care
  \value PositionAttribute   Position
  \value ColorAttribute      Color
  \value TexCoordAttribute   Texture coordinate
  \value TexCoord1Attribute  Texture coordinate 1
  \value TexCoord2Attribute  Texture coordinate 2
 
 */
 
/*!
    \enum QSGGeometry::DataPattern
 
    The DataPattern enum is used to specify the use pattern for the
    vertex and index data in a geometry object.
 
    \value AlwaysUploadPattern The data is always uploaded. This means
    that the user does not need to explicitly mark index and vertex
    data as dirty after changing it. This is the default.
 
    \value DynamicPattern The data is modified repeatedly and drawn
    many times.  This is a hint that may provide better
    performance. When set the user must make sure to mark the data as
    dirty after changing it.
 
    \value StaticPattern The data is modified once and drawn many
    times. This is a hint that may provide better performance. When
    set the user must make sure to mark the data as dirty after
    changing it.
 
    \value StreamPattern The data is modified for almost every time it
    is drawn. This is a hint that may provide better performance. When
    set, the user must make sure to mark the data as dirty after
    changing it.
 */
 
 
/*!
    \fn QSGGeometry::DataPattern QSGGeometry::indexDataPattern() const
 
    Returns the usage pattern for indices in this geometry. The default
    pattern is AlwaysUploadPattern.
 */
 
/*!
    Sets the usage pattern for indices to \a p.
 
    The default is AlwaysUploadPattern. When set to anything other than
    the default, the user must call markIndexDataDirty() after changing
    the index data, in addition to calling QSGNode::markDirty() with
    QSGNode::DirtyGeometry.
 */
 
void QSGGeometry::setIndexDataPattern(DataPattern p)
{
    m_index_usage_pattern = p;
}
 
 
 
 
/*!
    \fn QSGGeometry::DataPattern QSGGeometry::vertexDataPattern() const
 
    Returns the usage pattern for vertices in this geometry. The default
    pattern is AlwaysUploadPattern.
 */
 
/*!
    Sets the usage pattern for vertices to \a p.
 
    The default is AlwaysUploadPattern. When set to anything other than
    the default, the user must call markVertexDataDirty() after changing
    the vertex data, in addition to calling QSGNode::markDirty() with
    QSGNode::DirtyGeometry.
 */
 
void QSGGeometry::setVertexDataPattern(DataPattern p)
{
    m_vertex_usage_pattern = p;
}
 
 
 
 
/*!
    Mark that the vertices in this geometry has changed and must be uploaded
    again.
 
    This function only has an effect when the usage pattern for vertices is
    StaticData and the renderer that renders this geometry uploads the geometry
    into Vertex Buffer Objects (VBOs).
 */
void QSGGeometry::markIndexDataDirty()
{
    m_dirty_index_data = true;
}
 
 
 
/*!
    Mark that the vertices in this geometry has changed and must be uploaded
    again.
 
    This function only has an effect when the usage pattern for vertices is
    StaticData and the renderer that renders this geometry uploads the geometry
    into Vertex Buffer Objects (VBOs).
 */
void QSGGeometry::markVertexDataDirty()
{
    m_dirty_vertex_data = true;
}
 
 
QT_END_NAMESPACE