Add QSharedGLTexture

QAbstractTexture subclass that will allow to make Qt3D
work with a texture id created by another GL engine on
a shared context.

[ChangeLog][Qt3DRender] Add QSharedGLTexture to allow
creating a Qt3D from an OpenGL texture id.

Change-Id: Ic5b19eae6ebc7aca7e6372d62217348f99db19df
Task-number: QTBUG-69918
Reviewed-by: Kevin Ottens <kevin.ottens@kdab.com>

6 files changed, 94 insertions, 1 deletions

diff --git a/src/render/texture/qabstracttexture.cpp b/src/render/texture/qabstracttexture.cpp
index 03746620e..18ec3ccec 100644
--- a/src/render/texture/qabstracttexture.cpp
+++ b/src/render/texture/qabstracttexture.cpp
@@ -66,6 +66,7 @@ QAbstractTexturePrivate::QAbstractTexturePrivate()
     , m_comparisonMode(QAbstractTexture::CompareNone)
     , m_layers(1)
     , m_samples(1)
+    , m_sharedTextureId(-1)
 {
 }
 
@@ -909,6 +910,7 @@ Qt3DCore::QNodeCreatedChangeBasePtr QAbstractTexture::createNodeCreationChange()
     data.layers = d->m_layers;
     data.samples = d->m_samples;
     data.dataFunctor = d->m_dataFunctor;
+    data.sharedTextureId = d->m_sharedTextureId;
     return creationChange;
 }
 
diff --git a/src/render/texture/qabstracttexture_p.h b/src/render/texture/qabstracttexture_p.h
index a27ae3729..21b0fd9d3 100644
--- a/src/render/texture/qabstracttexture_p.h
+++ b/src/render/texture/qabstracttexture_p.h
@@ -87,6 +87,8 @@ public :
     int m_layers;
     int m_samples;
 
+    int m_sharedTextureId;
+
     QTextureGeneratorPtr dataFunctor() const;
     void setDataFunctor(const QTextureGeneratorPtr &generator);
 
@@ -113,6 +115,7 @@ struct QAbstractTextureData
     Qt3DCore::QNodeIdVector textureImageIds;
     int layers;
     int samples;
+    int sharedTextureId;
     QTextureGeneratorPtr dataFunctor;
 };
 
diff --git a/src/render/texture/qtexture.cpp b/src/render/texture/qtexture.cpp
index f7ee3f6df..110df30e3 100644
--- a/src/render/texture/qtexture.cpp
+++ b/src/render/texture/qtexture.cpp
@@ -1469,6 +1469,69 @@ bool QTextureFromSourceGenerator::isMirrored() const
     return m_mirrored;
 }
 
+/*!
+ * \class QSharedGLTexture
+ * \brief Allows to use a textureId from a separate OpenGL context in a Qt 3D scene.
+ *
+ * Depending on the rendering mode used by Qt 3D, the shared context will either be:
+ * \list
+ * \li qt_gl_global_share_context when letting Qt 3D drive the rendering. When
+ * setting the attribute Qt::AA_ShareOpenGLContexts on the QApplication class,
+ * this will automatically make QOpenGLWidget instances have their context shared
+ * with qt_gl_global_share_context.
+ * \li the shared context from the QtQuick scene. You might have to subclass
+ * QWindow or use QtQuickRenderControl to have control over what that shared
+ * context is though as of 5.13 it is qt_gl_global_share_context.
+ * \endlist
+ *
+ * \since 5.13
+ *
+ * Any 3rd party engine that shares its context with the Qt 3D renderer can now
+ * provide texture ids that will be referenced by the Qt 3D texture.
+ *
+ * You can omit specifying the texture properties, Qt 3D will try at runtime to
+ * determine what they are. If you know them, you can of course provide them,
+ * avoid additional work for Qt 3D.
+ *
+ * Keep in mind that if you are using custom materials and shaders, you need to
+ * specify the correct sampler type to be used.
+ */
+
+QSharedGLTexture::QSharedGLTexture(Qt3DCore::QNode *parent)
+    : QAbstractTexture(parent)
+{
+    QAbstractTexturePrivate *d = static_cast<QAbstractTexturePrivate *>(Qt3DCore::QNodePrivate::get(this));
+    d->m_target = TargetAutomatic;
+}
+
+QSharedGLTexture::~QSharedGLTexture()
+{
+}
+
+/*!
+ * \qmlproperty textureId
+ *
+ * The OpenGL texture id value that you want Qt3D to gain access to.
+ */
+/*!
+ *\property Qt3DRender::QSharedGLTexture::textureId
+ *
+ * The OpenGL texture id value that you want Qt3D to gain access to.
+ */
+int QSharedGLTexture::textureId() const
+{
+    return static_cast<QAbstractTexturePrivate *>(d_ptr.get())->m_sharedTextureId;
+}
+
+void QSharedGLTexture::setTextureId(int id)
+{
+    QAbstractTexturePrivate *d = static_cast<QAbstractTexturePrivate *>(Qt3DCore::QNodePrivate::get(this));
+    if (d->m_sharedTextureId != id) {
+        d->m_sharedTextureId = id;
+        emit textureIdChanged(id);
+    }
+}
+
 } // namespace Qt3DRender
 
 QT_END_NAMESPACE
diff --git a/src/render/texture/qtexture.h b/src/render/texture/qtexture.h
index 24d19fbcf..991725de2 100644
--- a/src/render/texture/qtexture.h
+++ b/src/render/texture/qtexture.h
@@ -169,6 +169,23 @@ private:
     Q_DECLARE_PRIVATE(QTextureLoader)
 };
 
+class QT3DRENDERSHARED_EXPORT QSharedGLTexture : public QAbstractTexture
+{
+    Q_OBJECT
+    Q_PROPERTY(int textureId READ textureId WRITE setTextureId NOTIFY textureIdChanged)
+public:
+    explicit QSharedGLTexture(Qt3DCore::QNode *parent = nullptr);
+    ~QSharedGLTexture();
+
+    int textureId() const;
+
+public Q_SLOTS:
+    void setTextureId(int id);
+
+Q_SIGNALS:
+    void textureIdChanged(int textureId);
+};
+
 } // namespace Qt3DRender
 
 QT_END_NAMESPACE
diff --git a/src/render/texture/texture.cpp b/src/render/texture/texture.cpp
index 749b85802..b87ea9c6d 100644
--- a/src/render/texture/texture.cpp
+++ b/src/render/texture/texture.cpp
@@ -115,6 +115,7 @@ void Texture::cleanup()
     // texture is being referenced by a shared API specific texture (GLTexture)
     m_dataFunctor.reset();
     m_textureImageIds.clear();
+    m_sharedTextureId = -1;
 
     // set default values
     m_properties = {};
@@ -181,6 +182,9 @@ void Texture::sceneChangeEvent(const Qt3DCore::QSceneChangePtr &e)
             dirty = DirtyProperties;
         } else if (propertyChange->propertyName() == QByteArrayLiteral("generator")) {
             setDataGenerator(propertyChange->value().value<QTextureGeneratorPtr>());
+        } else if (propertyChange->propertyName() == QByteArrayLiteral("textureId")) {
+            m_sharedTextureId = propertyChange->value().toInt();
+            dirty = DirtySharedTextureId;
         }
     }
         break;
@@ -315,6 +319,7 @@ void Texture::initializeFromPeer(const Qt3DCore::QNodeCreatedChangeBasePtr &chan
     m_parameters.comparisonFunction = data.comparisonFunction;
     m_parameters.comparisonMode = data.comparisonMode;
     m_dataFunctor = data.dataFunctor;
+    m_sharedTextureId = data.sharedTextureId;
 
     for (const QNodeId imgId : data.textureImageIds)
         addTextureImage(imgId);
diff --git a/src/render/texture/texture_p.h b/src/render/texture/texture_p.h
index 9e385cefe..d48e35b0c 100644
--- a/src/render/texture/texture_p.h
+++ b/src/render/texture/texture_p.h
@@ -137,7 +137,8 @@ public:
         DirtyProperties = 0x1,
         DirtyParameters = 0x2,
         DirtyImageGenerators = 0x4,
-        DirtyDataGenerator = 0x8
+        DirtyDataGenerator = 0x8,
+        DirtySharedTextureId = 0x16
     };
     Q_DECLARE_FLAGS(DirtyFlags, DirtyFlag)
 
@@ -155,6 +156,7 @@ public:
     inline const TextureParameters& parameters() const { return m_parameters; }
     inline const Qt3DCore::QNodeIdVector textureImageIds() const { return m_textureImageIds; }
     inline const QTextureGeneratorPtr& dataGenerator() const { return m_dataFunctor; }
+    inline int sharedTextureId() const { return m_sharedTextureId; }
 
     void setDataGenerator(const QTextureGeneratorPtr &generator);
     void updatePropertiesAndNotify(const TextureProperties &propreties);
@@ -165,6 +167,7 @@ private:
     DirtyFlags m_dirty;
     TextureProperties m_properties;
     TextureParameters m_parameters;
+    int m_sharedTextureId;
 
     QTextureGeneratorPtr m_dataFunctor;
     Qt3DCore::QNodeIdVector m_textureImageIds;