Qt3D 2.0 Sean Harmer James Turner Giuseppe D’Angelo Paul Lemire Qt3D History • Produced by the Brisbane office • Various odd restrictions and assumptions • Multithreading, multi-pass rendering • Unsuitable for serious use • User base : mostly students and academics • Unmaintained Qt3D 2.0 - Goals • Easy creation of interactive 3D scenes • Solid QML and C++ APIs • Extensible with arbitrary rendering techniques or vertex data by users • Reduce repeated work delivering 3D to clients • Make efficient use of multi-core CPUs and modern GPUs Qt3D 2.0 - Non-Goals • Compete with Unity or Unreal • Provide a huge library of shaders • Reimplement every visualisation in VTK Qt3D 2.0 - Feature Set • Scene defined by C++, QML or 3D scene files • Configurable rendering pipeline from C++ or QML • Integration with QtQuick UIs • Hierarchical bounding volume culling • 3D object picking Important Design Choices • Independent of QtQuick • Qt3D and Quick3D (Qt3D QML independent) • Promote a subsystem architecture (Aspects) • Generic renderer taking advantage of the available OpenGL version • Design inspired from high performance game engines Aspects • A subsystem within Qt3D • Has access to the SceneGraph tree • Can send jobs to the Jobs Manager • Allow to add features over time : • 3D Audio/OpenAL aspect • SkeletalAnimation aspect • Picking aspect Component based design • • • • Avoid multiple inheritance Easier to maintain and extend Data-driven architecture Each Aspect can define its components Qt3D Core • Aspects Manager • Nodes (Node, Entity, Component) • Abstracts and Interfaces (QAbstractMesh, QAbstractMaterial …) • Resources Management classes • Jobs Manager • QChangeArbiter : observers of observables Qt3D Core – The Render Loop while (true) { waitForNextTick(); foreach (Aspect *aspect, aspects) jobManager->enqueueJobs(aspect->jobs()); changeArbiter->syncChanges(); } Qt3D Renderer • Rendering Aspect • Define the Rendering pipeline using a FrameGraph • QGraphicContext : OpenGL helpers (3 / 2 / ES2) • 3D Scene file loaders (Assimp, GLTF, Collada) • Uses jobs to parallelize matrices computations and creation of OpenGL commands Quick3D • C++ classes registered to QML • Use of extension classes when needed to avoid dependencies to the QML module • qmlRegisterExtendedType Qt improvements • Make Qt types independent of QtQuick (Qt.vector3d …) • Could Animations be moved out of QtQuick as well ? • Public API for QQmlCustomParser What remains to be done • 3D Picking • QtQuick 2 integration • Fix rendering on Windows and OpenGL ES 2 • Develop a set of shaders / techniques