Hello,
Yes, in our case, the objects are rendered in same viewport and camera
with only difference being layer filters. I also tried setting the parent after
creating the entity, it didn't work.
In our application, each sub entity already has separate parent with
root entity being the grandparent of all, and the layer component is added to
the parent entity. I tried all combinations of adding layer to entities, only
the first filtered layer is properly pickable in all scenarios.
As you suggested, I created a small example and in it, I have
successfully reproduced this bug. I have attached the project in QTBUG-128299,
and assigned it to you. But I will paste the code here for reference:
//main.cpp
#include <QGuiApplication>
#include <Qt3DCore/qentity.h>
#include <Qt3DCore/qtransform.h>
#include <QtWidgets/QApplication>
#include <QtWidgets/QWidget>
#include <QtWidgets/QHBoxLayout>
#include <QtGui/QScreen>
#include <Qt3DRender/QRenderSurfaceSelector>
#include <Qt3DRender/qpointlight.h>
#include <Qt3DRender/QViewport>
#include <Qt3DRender/QObjectPicker>
#include <Qt3DRender/QNoDraw>
#include <Qt3DRender/QCameraSelector>
#include <Qt3DRender/QRenderStateSet>
#include <Qt3DRender/QLayerFilter>
#include <Qt3DRender/QDepthTest>
#include <Qt3DRender/QCullFace>
#include <Qt3DRender/QLayer>
#include <Qt3DRender/qcamera.h>
#include <Qt3DRender/qcameralens.h>
#include <Qt3DExtras/QSphereMesh>
#include <Qt3DExtras/qforwardrenderer.h>
#include <Qt3DExtras/QPhongMaterial>
#include <Qt3DExtras/qt3dwindow.h>
#include <Qt3DExtras/qfirstpersoncameracontroller.h>
#include <QApplication>
int main(int argc, char *argv[])
{
// I exclusively use opengl in my app but it has the same issue with QRhi.
/*
bool envvar = qputenv("QT3D_RENDERER", "opengl");
qDebug() << "Opengl Environment variable set:" << envvar;
QSurfaceFormat format = QSurfaceFormat::defaultFormat();
format.setDepthBufferSize(24);
format.setStencilBufferSize(8);
format.setSamples(4);
format.setVersion(3, 3);
format.setProfile(QSurfaceFormat::CoreProfile);
QSurfaceFormat::setDefaultFormat(format);
*/
QApplication app(argc, argv);
Qt3DExtras::Qt3DWindow *view = new Qt3DExtras::Qt3DWindow();
view->defaultFrameGraph()->setClearColor(QColor(QRgb(0x4d4d4f)));
QWidget *container = QWidget::createWindowContainer(view);
QSize screenSize = view->screen()->size();
container->setMinimumSize(QSize(200, 100));
container->setMaximumSize(screenSize);
QWidget *widget = new QWidget;
QHBoxLayout *hLayout = new QHBoxLayout(widget);
QVBoxLayout *vLayout = new QVBoxLayout();
vLayout->setAlignment(Qt::AlignTop);
hLayout->addWidget(container, 1);
hLayout->addLayout(vLayout);
widget->setWindowTitle(QStringLiteral("QObjectPicker bug"));
// Root entity
Qt3DCore::QEntity *rootEntity = new Qt3DCore::QEntity();
Qt3DRender::QCamera *cameraEntity = view->camera();
cameraEntity->lens()->setPerspectiveProjection(45.0f, 16.0f/9.0f, 0.1f,
1000.0f);
cameraEntity->setPosition(QVector3D(0, 0, 20.0f));
cameraEntity->setUpVector(QVector3D(0, 1, 0));
cameraEntity->setViewCenter(QVector3D(0, 0, 0));
Qt3DCore::QEntity *lightEntity = new Qt3DCore::QEntity(rootEntity);
Qt3DRender::QPointLight *light = new Qt3DRender::QPointLight(lightEntity);
light->setColor("white");
light->setIntensity(1);
lightEntity->addComponent(light);
Qt3DCore::QTransform *lightTransform = new
Qt3DCore::QTransform(lightEntity);
lightTransform->setTranslation(cameraEntity->position());
lightEntity->addComponent(lightTransform);
Qt3DExtras::QFirstPersonCameraController *camController = new
Qt3DExtras::QFirstPersonCameraController(rootEntity);
camController->setCamera(cameraEntity);
Qt3DRender::QLayer* opaqueLayer = new Qt3DRender::QLayer;
opaqueLayer->setRecursive(true);
opaqueLayer->setObjectName("Opaque Layer");
Qt3DRender::QLayer* transparentLayer = new Qt3DRender::QLayer;
transparentLayer->setRecursive(true);
transparentLayer->setObjectName("Transparent Layer");
// Framegraph starts here
auto renderSurfaceSelector = new Qt3DRender::QRenderSurfaceSelector;
renderSurfaceSelector->setSurface(view);
Qt3DRender::QClearBuffers* clearBuffers = new
Qt3DRender::QClearBuffers(renderSurfaceSelector);
clearBuffers->setBuffers(Qt3DRender::QClearBuffers::AllBuffers);
clearBuffers->setClearColor(Qt::gray);
Qt3DRender::QNoDraw* noDraw = new Qt3DRender::QNoDraw(clearBuffers);
Qt3DRender::QViewport* mainViewport = new
Qt3DRender::QViewport(renderSurfaceSelector);
mainViewport->setNormalizedRect(QRectF(0, 0, 1.0, 1.0));
Qt3DRender::QCameraSelector* cameraSelector = new
Qt3DRender::QCameraSelector(mainViewport);
cameraSelector->setCamera(view->camera());
Qt3DRender::QRenderStateSet* renderStateSet = new
Qt3DRender::QRenderStateSet(cameraSelector);
{
Qt3DRender::QDepthTest* depthTest = new Qt3DRender::QDepthTest;
depthTest->setDepthFunction(Qt3DRender::QDepthTest::LessOrEqual);
renderStateSet->addRenderState(depthTest);
Qt3DRender::QCullFace* cullFace = new
Qt3DRender::QCullFace(renderStateSet);
cullFace->setMode(Qt3DRender::QCullFace::NoCulling);
renderStateSet->addRenderState(cullFace);
}
// Opaque branch - try reversing with layerFilterTransparent. Change order
of both filters to reverse them.
Qt3DRender::QLayerFilter* layerFilterOpaque = new
Qt3DRender::QLayerFilter(renderStateSet);
layerFilterOpaque->addLayer(opaqueLayer);
// Transparent branch - try reversing with layerFilterOpaque
Qt3DRender::QLayerFilter* layerFilterTransparent = new
Qt3DRender::QLayerFilter(renderStateSet);
layerFilterTransparent->addLayer(transparentLayer);
view->setActiveFrameGraph(renderSurfaceSelector);
view->setRootEntity(rootEntity);
Qt3DCore::QEntity* redSphereEntity = new Qt3DCore::QEntity(rootEntity);
Qt3DExtras::QPhongMaterial* redSphereMaterial = new
Qt3DExtras::QPhongMaterial();
{
Qt3DExtras::QSphereMesh* sphereMesh = new Qt3DExtras::QSphereMesh();
sphereMesh->setRadius(3.0f);
sphereMesh->setRings(10);
Qt3DCore::QTransform* sphereTransform = new Qt3DCore::QTransform();
sphereTransform->setTranslation(QVector3D(-10.0f, 0.0f, 0.0f));
redSphereMaterial->setDiffuse(Qt::red);
Qt3DRender::QObjectPicker* subEntitypicker = new
Qt3DRender::QObjectPicker;
QObject::connect(subEntitypicker, &Qt3DRender::QObjectPicker::clicked,
[redSphereMaterial](){
qDebug() << "Red Picked";
if (redSphereMaterial->diffuse() == Qt::red)
{
redSphereMaterial->setDiffuse(Qt::yellow);
}
else
{
redSphereMaterial->setDiffuse(Qt::red);
}
});
redSphereEntity->addComponent(sphereMesh);
redSphereEntity->addComponent(sphereTransform);
redSphereEntity->addComponent(subEntitypicker);
redSphereEntity->addComponent(redSphereMaterial);
redSphereEntity->addComponent(opaqueLayer);
}
Qt3DCore::QEntity* blueSphereEntity = new Qt3DCore::QEntity(rootEntity);
Qt3DExtras::QPhongMaterial* blueSphereMaterial = new
Qt3DExtras::QPhongMaterial();
{
Qt3DExtras::QSphereMesh* sphereMesh = new Qt3DExtras::QSphereMesh();
sphereMesh->setRadius(3.0f);
sphereMesh->setRings(10);
Qt3DCore::QTransform* sphereTransform = new Qt3DCore::QTransform();
sphereTransform->setTranslation(QVector3D(10.0f, 0.0f, 0.0f));
Qt3DRender::QObjectPicker* subEntitypicker = new
Qt3DRender::QObjectPicker;
blueSphereMaterial->setDiffuse(Qt::blue);
QObject::connect(subEntitypicker, &Qt3DRender::QObjectPicker::clicked,
[blueSphereMaterial](){
qInfo() << "Blue Picked";
if (blueSphereMaterial->diffuse() == Qt::blue)
{
blueSphereMaterial->setDiffuse(Qt::yellow);
}
else
{
blueSphereMaterial->setDiffuse(Qt::blue);
}
});
blueSphereEntity->addComponent(sphereMesh);
blueSphereEntity->addComponent(subEntitypicker);
blueSphereEntity->addComponent(sphereTransform);
blueSphereEntity->addComponent(blueSphereMaterial);
blueSphereEntity->addComponent(transparentLayer);
}
qDebug() << "Try to click red and blue sphere. Red has first filtered layer
as component and blue has second filtered layer as component";
qDebug() << "When picked, spheres change color. You will notice blue cannot
be picked as it has second filtered layer in framegraph";
qDebug() << "You can try reversing the order of layer filter nodes in
framegraph to see the other sphere picked";
// Show window
widget->show();
widget->resize(1200, 800);
return app.exec();
}
// End of main.cpp
#CMakeLists.txt
cmake_minimum_required(VERSION 3.14)
project(sample_test LANGUAGES CXX)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
find_package(Qt6 REQUIRED COMPONENTS 3DCore 3DExtras 3DInput 3DRender Core Gui
Widgets)
add_executable(sample_test
main.cpp
)
target_link_libraries(sample_test
Qt6::3DCore
Qt6::3DExtras
Qt6::3DInput
Qt6::3DRender
Qt6::Core
Qt6::Gui
Qt6::Widgets
)
include(GNUInstallDirs)
install(TARGETS sample_test
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
)
# End of CMakeLists.txt
In this simple example, picking doesn't work for the transparentLayer,
but it works for opaqueLayer. Hope to find a solution for this as using
multiple QLayerFilters seems to be the only way to handle transparency
correctly. If there is an alternative way to achieve perfect transparency(which
is not possible in QSortPolicy), please let me know. Thanks.
Regards,
Sakthi
sakth...@vjcs.com
-----Original Message-----
From: Mike Krus [mailto:mike.k...@kdab.com]
Sent: 22 August 2024 20:49
To: sakth...@vjcs.com
Cc: interest@qt-project.org
Subject: Re: [Interest] Qt3D - QObjectPicker doesn't work with multiple QLayers
and QLayerFilters
Hi
the frame affects picking in a couple of ways:
- the layer filter, entities should only be pickable if the filter accepts the
entities, otherwise they would be ignored
- the camera and viewport that are active in the branch (this affect the
picking ray that gets tested)
I’m assuming in your case the only difference is the layer filter?
If seems like there may be an issue with the dynamic nature of your scene graph
and
Qt3D’s backend not being updated properly.
A few things to try:
- when creating new entities, create them without a parent, add the components
and children, then set the parent
- if possible with your scene graph, maybe have separate parents for opaque and
transparent entities (rather than
mixing them under the same parent), and add the layer component to the parent
entities rather then each entity
(making sure you mark it as recursive).
I don’t think these should change the issue but might be something worth trying.
If you have a small example I can use to reproduce the issue, please create a
bug report and assign it to me.
Mike
> On 22 Aug 2024, at 14:19, Sakthi G <sakth...@vjcs.com> wrote:
>
> Hello, We have a Qt3D application where we have multiple QLayers for
> different types of meshes. We have found out that QObjectPicker doesn’t work
> properly with multiple QLayers. It doesn’t get triggered consistently if the
> entity has layer component which is not filtered at the top of the framegraph.
> Consider the following simplified framegraph with two layer filter branches,
> one for opaque and one for transparent objects:
> Qt3DRender::QViewport* mainViewport = new
> Qt3DRender::QViewport(renderSurfaceSelector);
> mainViewport->setNormalizedRect(QRectF(0, 0, 1.0, 1.0));
> Qt3DRender::QCameraSelector* cameraSelector = new
> Qt3DRender::QCameraSelector(mainViewport);
> cameraSelector->setCamera(view->camera());
> Qt3DRender::QRenderStateSet* renderStateSet = new
> Qt3DRender::QRenderStateSet(cameraSelector);
> {
> Qt3DRender::QDepthTest* depthTest = new Qt3DRender::QDepthTest;
> depthTest->setDepthFunction(Qt3DRender::QDepthTest::LessOrEqual);
> renderStateSet->addRenderState(depthTest);
> Qt3DRender::QCullFace* cullFace = new
> Qt3DRender::QCullFace(renderStateSet);
> cullFace->setMode(Qt3DRender::QCullFace::NoCulling);
> renderStateSet->addRenderState(cullFace);
> }
> // Opaque branch
> Qt3DRender::QLayerFilter* layerFilterOpaque = new
> Qt3DRender::QLayerFilter(renderStateSet);
> layerFilterOpaque->addLayer(opaqueLayer);
> // Transparent branch
> Qt3DRender::QLayerFilter* layerFilterTransparent = new
> Qt3DRender::QLayerFilter(renderStateSet);
> layerFilterTransparent->addLayer(transparentLayer);
> When we dynamically add meshes to the scene, we check if the default
> material is transparent and assign the respective layers like this:
> if (transparent)
> {
> entity->addComponent(transparentLayer);
> }
> else
> {
> entity->addComponent(opaqueLayer);
> }
> After this, when we click on the dynamically added mesh, only entities with
> opaqueLayer get triggered 100% of time, entities with transparentLayer gets
> triggered inconsistently, and sometimes, it gets triggered if we click the
> backface of the mesh. The hit ratio is around 20%.
> If we swap the order of layer filters in framegraph, the transparentLayer
> entities get triggered 100% of time and the opaqueLayer entities get
> triggered inconsistently. So we think that it is the framegraph which is
> causing this problem. But if we modify a material and change the layers of
> an existing entity(with opaqueLayer), QObjectPicker gets triggered all the
> time. The following code demonstrates how we do that:
> pickedEntity->addComponent(transparentLayer);
> pickedEntity->removeComponent(opaqueLayer);
> pickedEntity->setEnabled(false);
> pickedEntity->setEnabled(true);
> Additionally, we also found that if the same scene with the above mentioned
> framegraph only contains dynamically created entities with transparentLayer
> as a component, QObjectPicker is not triggered at all. How to fix this
> issue? Why does it work if we modify the layer after creating it with
> opaqueLayer, but not when adding dynamically while creating? Does
> QObjectPicker depend on how we setup the framegraph? We couldn’t find any
> documentation/code/forum posts linking QLayer/QLayerFilter with
> QObjectPicker. Your help is truly appreciated.
> Regards,
> Sakthi
> sakth...@vjcs.com
>
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KDAB (UK) Ltd., a KDAB Group company
Tel: UK Office +44 1625 809908 Mobile +44 7833 491941
KDAB - The Qt Experts, C++, OpenGL Experts
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