Add partial data update support for QBuffer

Perform upadateData through queue of replacements specified by
QBufferUpdate: start position (offset) and QByteArray (replacing data)

Add example based on custom-mesh-cpp to show how updating data works.

Task-number: QTBUG-50720
Change-Id: I2eceb514af21209deb278d73c94773e39f300fb3
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

2 files changed, 21 insertions, 9 deletions

diff --git a/src/quick3d/quick3drender/items/quick3dbuffer.cpp b/src/quick3d/quick3drender/items/quick3dbuffer.cpp
index 73292a3b5..68ac21577 100644
--- a/src/quick3d/quick3drender/items/quick3dbuffer.cpp
+++ b/src/quick3d/quick3drender/items/quick3dbuffer.cpp
@@ -57,12 +57,12 @@ namespace {
 const int jsValueTypeId = qMetaTypeId<QJSValue>();
 }
 
-Quick3DBuffer::Quick3DBuffer(QObject *parent)
-    : QObject(parent)
+Quick3DBuffer::Quick3DBuffer(Qt3DCore::QNode *parent)
+    : Qt3DRender::QBuffer(QBuffer::VertexBuffer, parent)
     , m_engine(nullptr)
     , m_v4engine(nullptr)
 {
-    QObject::connect(parentBuffer(), &Qt3DRender::QBuffer::dataChanged, this, &Quick3DBuffer::bufferDataChanged);
+    QObject::connect(this, &Qt3DRender::QBuffer::dataChanged, this, &Quick3DBuffer::bufferDataChanged);
 }
 
 QByteArray Quick3DBuffer::convertToRawData(const QJSValue &jsValue)
@@ -83,16 +83,26 @@ QByteArray Quick3DBuffer::convertToRawData(const QJSValue &jsValue)
 
 QVariant Quick3DBuffer::bufferData() const
 {
-    return QVariant::fromValue(parentBuffer()->data());
+    return QVariant::fromValue(data());
 }
 
 void Quick3DBuffer::setBufferData(const QVariant &bufferData)
 {
     if (bufferData.userType() == QMetaType::QByteArray) {
-        parentBuffer()->setData(bufferData.toByteArray());
+        QBuffer::setData(bufferData.toByteArray());
     } else if (bufferData.userType() == jsValueTypeId) {
         QJSValue jsValue = bufferData.value<QJSValue>();
-        parentBuffer()->setData(convertToRawData(jsValue));
+        QBuffer::setData(convertToRawData(jsValue));
+    }
+}
+
+void Quick3DBuffer::updateData(int offset, const QVariant &bufferData)
+{
+    if (bufferData.userType() == QMetaType::QByteArray) {
+        QBuffer::updateData(offset, bufferData.toByteArray());
+    } else if (bufferData.userType() == jsValueTypeId) {
+        QJSValue jsValue = bufferData.value<QJSValue>();
+        QBuffer::updateData(offset, convertToRawData(jsValue));
     }
 }
 
diff --git a/src/quick3d/quick3drender/items/quick3dbuffer_p.h b/src/quick3d/quick3drender/items/quick3dbuffer_p.h
index 512e6936c..c5cb39cdf 100644
--- a/src/quick3d/quick3drender/items/quick3dbuffer_p.h
+++ b/src/quick3d/quick3drender/items/quick3dbuffer_p.h
@@ -69,17 +69,19 @@ namespace Render {
 
 namespace Quick {
 
-class QT3DQUICKRENDERSHARED_PRIVATE_EXPORT Quick3DBuffer : public QObject
+class QT3DQUICKRENDERSHARED_PRIVATE_EXPORT Quick3DBuffer : public Qt3DRender::QBuffer
 {
     Q_OBJECT
     Q_PROPERTY(QVariant data READ bufferData WRITE setBufferData NOTIFY bufferDataChanged)
 public:
-    explicit Quick3DBuffer(QObject *parent = nullptr);
-    inline QBuffer *parentBuffer() const { return qobject_cast<QBuffer *>(parent()); }
+    explicit Quick3DBuffer(Qt3DCore::QNode *parent = nullptr);
 
     QVariant bufferData() const;
     void setBufferData(const QVariant &bufferData);
 
+public Q_SLOTS:
+    void updateData(int offset, const QVariant &bytes);
+
 Q_SIGNALS:
     void bufferDataChanged();