So I have a game in Windows Phone's version of cocos2dx. There is a background (CCLayerColor) and in the middle of it I place another CCLayerColor. The problem is that, when moving a layer with sprites inside that middle layer, the movement is done relative to the whole screen, not to the layer in middle.
The code for creating this CClayerColor in the middle of the screen is:
mWheelMachine = WheelMachineView::create(symbolMap, path);
mWheelMachine->setContentSize(CCSize(WHEEL_MACHINE_WIDTH , WHEEL_MACHINE_HEIGHT));//values equaling one third of screen size
mWheelMachine->setPosition(ItemManager::sharedItemManager()->getItemPosition(WHEEL_MACHINE_TAG
addChild(mWheelMachine, THEME_WHEEL_MACHINE_ORDER);//position in the middle of the screen
"WheelMachineView" is a subclass of "CCLayerColor", while create just overrides the correspondent of CCLayerColor.
Inside this class, I have another layer that moves along with its CCSprite objects drawn inside.
unsigned short o;
for (unsigned short i = 0; i < NUMBER_OF_WHEELS; i++)
{
WheelView* wheelLayer = WheelView::create();
wheelLayer->setIsRelativeAnchorPoint(true);
wheelLayer->setAnchorPoint(ccp(0,0));
wheelLayer->setPosition(i * WHEEL_WIDTH, -100 );
wheelLayer->setContentSize(CCSize(WHEEL_WIDTH, WHEEL_HEIGHT)); //large height value, to have room for making an animation with moving symbols
addChild(wheelLayer);
mWheels.push_back(wheelLayer);
/* Get the wheel symbols */
list<Symbol*> wheelSymbols = mWheelModel->getWheelSymbols(i);
/* Index */
o = 0;
for (list<Symbol*>::reverse_iterator it = wheelSymbols.rbegin(); it != wheelSymbols.rend(); it++)
{
CCSprite* symbol = CCSprite::spriteWithSpriteFrameName((*it)->getName().c_str());
symbol->setPosition(ccp(WHEEL_WIDTH / 2, SYMBOL_HEIGHT/2 + (o++ * SYMBOL_HEIGHT) - SYMBOL_HEIGHT));
symbol->setAnchorPoint(ccp(0.5f, 0.5f));
symbol->setScale(SYMBOL_SCALE_FACTOR);
wheelLayer->addChild(symbol, 10, o);
}
}
So, when moving 'wheelLayer' to a position outside the content size of 'mWheelMachine', it will move over the entire screen, thus drawing the symbols outside the middle designated area (mWheelMachine) for that. As it has a larger size than its parent, it draws symbols outside the parent.
Why is this happening? How can I make it to only use mWheelMachine's content size?
You can imagine cclayer is a node, it does not have the concept of size and anchor and set its content size does not have a role on the show's content, it will only affect the control area.
I think you should just hope that some of the pictures to be displayed in a region. Using a mask will be a good solution.
Related
I am currently working on a project that I use C++, OpenGL, Qt 5.9.2 and Microsoft Visual Studio Professional 2015 on a 64 bit Operating System, Windows 10 Pro.
I have a user interface that I have created and in that user interface, there is a QGLWidget, that I am using for draw processes, with other widgets like push buttons and a dockWidget. I have a class Ball and it has variables(distance(double) and angle(int)) that determines where an instance of that Ball is going to be drawn inside the QGLWidget. Ball class has got 2 more variables that is, id(int), model(String) and year(int) Every other draw process draws lines except Ball drawings.
Drawings are 2 dimensional.
Every Ball has the same color(rgb)!
First problem: I want to left click to one of the Ball instances and I want to display it's id, model and year at The dockWidget.
Second Problem: While doing the stuff that I have mentioned at the First Problem section. I want the cursor image to change while hovering above any of the Ball instances, and change back to default Windows mouse cursor while not.
I have created a function that checks if the MouseEvent is LeftClick:
void DisplayManager::mousePressEvent(QMouseEvent* ev) {
if (ev->buttons() & Qt::LeftButton) { // Balls Are Green
if(// CHECK IF THERE IS A BALL AT THE CLICKED COORDINATES) {
// DISPLAY THE X and Y OF THE BALL AT THE DOCK WIDGET
}
}
}
This is my initializeGL function: (DisplayManager is the name of my QGLWidget)
void DisplayManager::initializeGL() {
glEnable(GL_COLOR_MATERIAL); // Enables the changing of the draw color with glColor() functions
glColor3f(0.0, 1.0, 0.0);
glEnable(GL_DEPTH_TEST);
glClearColor(0, 0, 0, 1); //sets a black background 1 0 0 1
}
On the basis this is a Picking problem and there are several information about it at the internet but I am not using GLUT and I am not using any shader. So in the light of all these I was unable to find any effective solution or clue about how can I accomplish all that I want.
I would be really glad if someone could help me with at least one of these problems.
I have currently finished working with the project. I thought that I should provide an answer to my question in case someone with a similar problem comes across with my question in the future.
void DisplayManager::mousePressEvent(QMouseEvent* ev) {
// The processes that are being executed after a left mouse button click on the DisplayManager.
if (ev->buttons() & Qt::LeftButton) {
double aspectRatio = openGLWidgetWidth / openGLWidgetHeight;
int xOfClicked = ev->x() - (openGLWidgetWidth / 2);
int yOfClicked = - (ev->y() - (openGLWidgetHeight / 2));
// The variable to be used for calculating fault tolerance of the click event.
int distanceBetweenPressAndDraw = 0;
// Executes the processes inside for every ball in vector.
for (int i = 0; i < ballVector.length(); i++) {
// Calculates the screen coordinates of the i'th ball.
int rangeOfBallInScreenDistance = rangeToScreenDistance(ballVector.at(i).range);
double screenXOfBall = rangeOfBallInScreenDistance * sin(ballVector.at(i).degree * DEGTORAD);
double screenYOfBall = rangeOfBallInScreenDistance * cos(ballVector.at(i).degree * DEGTORAD);
// Calculates the distance between pressed position and the i'th ball according to the screen coordinates.
distanceBetweenPressAndDraw = sqrt(pow((screenXOfBall - xOfClicked), 2) + pow((screenYOfBall - yOfClicked), 2));
// Decides if the clicked position is a ball (considering the fault tolerance).
if (distanceBetweenPressAndDraw < 10) {
emit printXY(QPointF(xOfClicked, yOfClicked)); // Prints the screen coordinates of the clicked positions (At the Dock Widget inside Main Window).
}
}
}
}
This was the solution for my First Problem. I would be glad though if someone could answer my Second problem in a comment or answer somehow.
I have a function that draws triangles through OpenGL
I draw two triangles by pressing a button (function on_drawMapPushButton_clicked()).
Then i draw a sphere that placed above these triangles. And now i see, that sphere is drawed correctly over first triangle, but second triangle drawed over the sphere and not vice versa.
If i press the button second time, then spehere is drawed correctly over first and second triangles.
When i press the button third time, then second triangle drawed over the sphere again.
When i press the button fourth time, then spehere is drawed correctly over first and second triangles and so on.
If i use in sphereMesh QPhongMaterial instead of QPhongAlphaMaterial, then spehere is drawed correctly over first and second triangles always. Like it must to be.
I can't understand what i do wrong to get my sphere is drawed always over the triangles.
Code, that draws transparent sphere:
selectModel_ = new Qt3DExtras::QSphereMesh(selectEntity_);
selectModel_->setRadius(75);
selectModel_->setSlices(150);
selectMaterial_ = new Qt3DExtras::QPhongAlphaMaterial(selectEntity_);
selectMaterial_->setAmbient(QColor(28, 61, 136));
selectMaterial_->setDiffuse(QColor(11, 56, 159));
selectMaterial_->setSpecular(QColor(10, 67, 199));
selectMaterial_->setShininess(0.8f);
selectEntity_->addComponent(selectModel_);
selectEntity_->addComponent(selectMaterial_);
Function drawTriangles:
void drawTriangles(QPolygonF triangles, QColor color){
int numOfVertices = triangles.size();
// Create and fill vertex buffer
QByteArray bufferBytes;
bufferBytes.resize(3 * numOfVertices * static_cast<int>(sizeof(float)));
float *positions = reinterpret_cast<float*>(bufferBytes.data());
for(auto point : triangles){
*positions++ = static_cast<float>(point.x());
*positions++ = 0.0f; //We need to drow only on the surface
*positions++ = static_cast<float>(point.y());
}
geometry_ = new Qt3DRender::QGeometry(mapEntity_);
auto *buf = new Qt3DRender::QBuffer(geometry_);
buf->setData(bufferBytes);
positionAttribute_ = new Qt3DRender::QAttribute(mapEntity_);
positionAttribute_->setName(Qt3DRender::QAttribute::defaultPositionAttributeName());
positionAttribute_->setVertexBaseType(Qt3DRender::QAttribute::Float); //In our buffer we will have only floats
positionAttribute_->setVertexSize(3); // Size of a vertex
positionAttribute_->setAttributeType(Qt3DRender::QAttribute::VertexAttribute); // Attribute type
positionAttribute_->setByteStride(3 * sizeof(float));
positionAttribute_->setBuffer(buf);
geometry_->addAttribute(positionAttribute_); // Add attribute to ours Qt3DRender::QGeometry
// Create and fill an index buffer
QByteArray indexBytes;
indexBytes.resize(numOfVertices * static_cast<int>(sizeof(unsigned int))); // start to end
unsigned int *indices = reinterpret_cast<unsigned int*>(indexBytes.data());
for(unsigned int i = 0; i < static_cast<unsigned int>(numOfVertices); ++i) {
*indices++ = i;
}
auto *indexBuffer = new Qt3DRender::QBuffer(geometry_);
indexBuffer->setData(indexBytes);
indexAttribute_ = new Qt3DRender::QAttribute(geometry_);
indexAttribute_->setVertexBaseType(Qt3DRender::QAttribute::UnsignedInt); //In our buffer we will have only unsigned ints
indexAttribute_->setAttributeType(Qt3DRender::QAttribute::IndexAttribute); // Attribute type
indexAttribute_->setBuffer(indexBuffer);
indexAttribute_->setCount(static_cast<unsigned int>(numOfVertices)); // Set count of our vertices
geometry_->addAttribute(indexAttribute_); // Add the attribute to ours Qt3DRender::QGeometry
shape_ = new Qt3DRender::QGeometryRenderer(mapEntity_);
shape_->setPrimitiveType(Qt3DRender::QGeometryRenderer::Triangles);
shape_->setGeometry(geometry_);
//Create material
material_ = new Qt3DExtras::QPhongMaterial(mapEntity_);
material_->setAmbient(color);
trianglesEntity_ = new Qt3DCore::QEntity(mapEntity_);
trianglesEntity_->addComponent(shape_);
trianglesEntity_->addComponent(material_);
}
Press button handler on_drawMapPushButton_clicked():
void on_drawMapPushButton_clicked()
{
clearMap(); //Implementation is above
QPolygonF triangle1;
triangle1 << QPointF( 0 ,-1000) << QPointF(0 ,1000) << QPointF(1000, -1000);
drawTriangles(triangle1, Qt::black);
QPolygonF triangle2;
triangle2 << QPointF(-1000,-1000) << QPointF(-100,1000) << QPointF(-100,-1000);
drawTriangles(triangle2, Qt::red);
}
Map clearing function clearMap():
void clearMap()
{
if(mapEntity_){
delete mapEntity_;
mapEntity_ = nullptr;
mapEntity_ = new Qt3DCore::QEntity(view3dRootEntity_);
}
}
Ok here comes the extend answer.
The reason why this sometimes happens and sometimes not depends on the order of your entities. If you experiment with two simple spheres, one transparent and one not, you will see that when the sphere that is transparent is added later it will be drawn above the opaque object - just like you want it to.
This happens because the opaque object will be drawn first (it comes first in the scene graph) and the transparent object later which will give you the result you want. In the other case where the transparent object gets drawn first, the opaque object is drawn above because the QPhongAlphaMaterial has a QNoDepthMask render state which tells it not to write to the depth buffer. Thus, the opaque object always passes the depth test, where the transparent object actually already drew to. You have to do some more work to properly draw transparent objects for arbitrary scene graphs and camera positions.
The Qt3D Rendering Graph
To understand what you have to do you should understand how the Qt3D rendering graph is laid out. If you know this already you can skip this part.
Italic words reference items in the graph image in the following text.
If you use a Qt3DWindow, you can't access the root node of rendering graph. It is maintained by the window. You can access the QRenderSettings and root node of your framegraph through the functions activeFramegraph() and renderSettings() which you can both call on the window. You can also set the root node of scene graph through the setRootEntity() function of Qt3DWindow. The window internally has a QAspectEngine, where it sets the root node of the whole graph, which is the root node of the rendering graph in the graph image above.
If you want to insert a framegraph node to the existing framegraph of the 3D window, you have to add it as the parent of the active framegraph which I will explain in the next section. If you have your own custom framegraph which you set on the window through setActiveFramegraph() then just append it to the end, this should suffice.
Using QSortPolicy
As you already found out according to you other questions, you can use QSortPolicy in your framegraph to sort the entities by distance to camera. You can add a sort policy as follows (assuming that view is your Qt3DWindow and scene is your root entity of the scene graph, although I don't understand why it has to be):
Qt3DRender::QFrameGraphNode *framegraph = view.activeFrameGraph();
Qt3DRender::QSortPolicy *sortPolicy = new Qt3DRender::QSortPolicy(scene);
framegraph->setParent(sortPolicy);
QVector<Qt3DRender::QSortPolicy::SortType> sortTypes =
QVector<Qt3DRender::QSortPolicy::SortType>() << Qt3DRender::QSortPolicy::BackToFront;
sortPolicy->setSortTypes(sortTypes);
view.setActiveFrameGraph(framegraph);
The issue with this code is that this sort policy sorts the entities by the distance of their centers to the camera. If one of the opaque objects is closer to the camera than the transparent object it gets drawn later anyways and occludes the transparent object. See the images below for a graphical explanation.
The red and black sphere are further away from the camera than the torus, that's why they get drawn first and they don't occlude the torus.
No the center of the red sphere is closer to the camera than the center of the torus. It gets rendered later than the torus and occludes it.
Using Two Framegraph Branches
You can tackle the issue above if you use two framegraph branches. One which draws all opaque entities and one which draws all transparent ones. To achieve this you have to make use of QLayer and QLayerFilter. You can attach layers to entities and then add layer filters to your framegraph. This way you can exclude entities from entering a certain branch of your framegraph.
Let's say you create two layers, one for opaque objects and one for transparents ones:
Qt3DRender::QLayer *transparentLayer = new Qt3DRender::QLayer;
Qt3DRender::QLayer *opaqueLayer = new Qt3DRender::QLayer;
You have to attach the transparent layer to each transparent object and the opaque layer to each opaque object as a component (using addComponent()).
Unfortunately, you need a special framegraph tree to include the two corresponding layer filters (again, assuming that view is your Qt3DWindow):
Qt3DRender::QRenderSurfaceSelector *renderSurfaceSelector
= new Qt3DRender::QRenderSurfaceSelector();
renderSurfaceSelector->setSurface(&view);
Qt3DRender::QClearBuffers *clearBuffers
= new Qt3DRender::QClearBuffers(renderSurfaceSelector);
clearBuffers->setBuffers(Qt3DRender::QClearBuffers::AllBuffers);
clearBuffers->setClearColor(Qt::white);
This is the first branch to clear the buffers. Now you add the following code:
Qt3DRender::QViewport *viewport = new Qt3DRender::QViewport(renderSurfaceSelector);
Qt3DRender::QCameraSelector *cameraSelector = new Qt3DRender::QCameraSelector(viewport);
Qt3DRender::QCamera *camera = new Qt3DRender::QCamera(cameraSelector);
// set your camera parameters here
cameraSelector->setCamera(camera);
Since you create the QViewport as a child of the QRenderSurfaceSelector it is now a sibling in your framegraph with respect to the QClearBuffers. You can see an illustration of the example framegraphs here.
Now you have to create the two leaf nodes that contain the layer filters. The Qt3D engine always executes a whole branch when it reaches a leaf. This means that first the opaque objects are drawn and then the transparent ones.
// not entirely sure why transparent filter has to go first
// I would have expected the reversed order of the filters but this works...
Qt3DRender::QLayerFilter *transparentFilter = new Qt3DRender::QLayerFilter(camera);
transparentFilter->addLayer(transparentLayer);
Qt3DRender::QLayerFilter *opaqueFilter = new Qt3DRender::QLayerFilter(camera);
opaqueFilter->addLayer(opaqueLayer);
The two layer filters are now leaf nodes in your framegraph branch and Qt3D will first draw the opaque objects and then afterwards, since it uses the same viewport and everything, will draw the transparent objects above. It will draw them correctly (i.e. not in front of parts of opaque objects that the transparent object actually lies behind, because we did not clear the depth buffers again -> Splitting the framegraph happens only on the camera node).
Now set the new framegaph on your Qt3DWindow:
view.setActiveFrameGraph(renderSurfaceSelector);
Result:
Edit (26.03.21): As Patrick B. pointed out correctly, using the suggested solution with two layers you will have to add both layers as components to any lights in the scene. You can get around this by setting the filter mode on the QLayerFilters to QLayerFilter::FilterMode::DiscardAnyMatching and then reverse the order of the filters. This way, the transparentFilter discards any entities with the transparentLayer attached - but not the lights because they don't have the transparentLayer. Vice versa for the opaqueFilter.
My mistake was that i did wrong order of creating and deletion of Triangles and Sphere entities.
In pseudo code right order is as follows:
clearTriangles();
clearSphere();
drawTriangles();
drawSphere();
If you are using Qt3d with QML and want to control the order elements are drawn you can control it by the order of layers in your QML file.
Something like:
{
objectName: "firstLayer"
id : firstLayer
}
Layer {
objectName: "secondLayer"
id: secondLayer
}
The order you add them to layer filters will then control which is drawn first:
RenderSurfaceSelector {
CameraSelector {
id : cameraSelector
camera: mainCamera
FrustumCulling {
ClearBuffers {
buffers : ClearBuffers.AllBuffers
clearColor: "#04151c"
NoDraw {}
}
LayerFilter
{
objectName: "firstLayerFilter"
id: firstLayerFilter
layers: [firstLayer]
}
LayerFilter
{
id: secondLayerFilter
objectName: "secondLayerFilter"
layers: [secondLayer]
}
Then anything you add to the secondLayer will get drawn over-top of the first layer. I used this to make sure text always showed up in front of shapes, but it can be used similarly with transparencies.
I have a function that draws triangles through OpenGL
I draw two triangles by pressing a button (function on_drawMapPushButton_clicked()).
Then i draw a sphere that placed above these triangles. And now i see, that sphere is drawed correctly over first triangle, but second triangle drawed over the sphere and not vice versa.
If i press the button second time, then spehere is drawed correctly over first and second triangles.
When i press the button third time, then second triangle drawed over the sphere again.
When i press the button fourth time, then spehere is drawed correctly over first and second triangles and so on.
If i use in sphereMesh QPhongMaterial instead of QPhongAlphaMaterial, then spehere is drawed correctly over first and second triangles always. Like it must to be.
I can't understand what i do wrong to get my sphere is drawed always over the triangles.
Code, that draws transparent sphere:
selectModel_ = new Qt3DExtras::QSphereMesh(selectEntity_);
selectModel_->setRadius(75);
selectModel_->setSlices(150);
selectMaterial_ = new Qt3DExtras::QPhongAlphaMaterial(selectEntity_);
selectMaterial_->setAmbient(QColor(28, 61, 136));
selectMaterial_->setDiffuse(QColor(11, 56, 159));
selectMaterial_->setSpecular(QColor(10, 67, 199));
selectMaterial_->setShininess(0.8f);
selectEntity_->addComponent(selectModel_);
selectEntity_->addComponent(selectMaterial_);
Function drawTriangles:
void drawTriangles(QPolygonF triangles, QColor color){
int numOfVertices = triangles.size();
// Create and fill vertex buffer
QByteArray bufferBytes;
bufferBytes.resize(3 * numOfVertices * static_cast<int>(sizeof(float)));
float *positions = reinterpret_cast<float*>(bufferBytes.data());
for(auto point : triangles){
*positions++ = static_cast<float>(point.x());
*positions++ = 0.0f; //We need to drow only on the surface
*positions++ = static_cast<float>(point.y());
}
geometry_ = new Qt3DRender::QGeometry(mapEntity_);
auto *buf = new Qt3DRender::QBuffer(geometry_);
buf->setData(bufferBytes);
positionAttribute_ = new Qt3DRender::QAttribute(mapEntity_);
positionAttribute_->setName(Qt3DRender::QAttribute::defaultPositionAttributeName());
positionAttribute_->setVertexBaseType(Qt3DRender::QAttribute::Float); //In our buffer we will have only floats
positionAttribute_->setVertexSize(3); // Size of a vertex
positionAttribute_->setAttributeType(Qt3DRender::QAttribute::VertexAttribute); // Attribute type
positionAttribute_->setByteStride(3 * sizeof(float));
positionAttribute_->setBuffer(buf);
geometry_->addAttribute(positionAttribute_); // Add attribute to ours Qt3DRender::QGeometry
// Create and fill an index buffer
QByteArray indexBytes;
indexBytes.resize(numOfVertices * static_cast<int>(sizeof(unsigned int))); // start to end
unsigned int *indices = reinterpret_cast<unsigned int*>(indexBytes.data());
for(unsigned int i = 0; i < static_cast<unsigned int>(numOfVertices); ++i) {
*indices++ = i;
}
auto *indexBuffer = new Qt3DRender::QBuffer(geometry_);
indexBuffer->setData(indexBytes);
indexAttribute_ = new Qt3DRender::QAttribute(geometry_);
indexAttribute_->setVertexBaseType(Qt3DRender::QAttribute::UnsignedInt); //In our buffer we will have only unsigned ints
indexAttribute_->setAttributeType(Qt3DRender::QAttribute::IndexAttribute); // Attribute type
indexAttribute_->setBuffer(indexBuffer);
indexAttribute_->setCount(static_cast<unsigned int>(numOfVertices)); // Set count of our vertices
geometry_->addAttribute(indexAttribute_); // Add the attribute to ours Qt3DRender::QGeometry
shape_ = new Qt3DRender::QGeometryRenderer(mapEntity_);
shape_->setPrimitiveType(Qt3DRender::QGeometryRenderer::Triangles);
shape_->setGeometry(geometry_);
//Create material
material_ = new Qt3DExtras::QPhongMaterial(mapEntity_);
material_->setAmbient(color);
trianglesEntity_ = new Qt3DCore::QEntity(mapEntity_);
trianglesEntity_->addComponent(shape_);
trianglesEntity_->addComponent(material_);
}
Press button handler on_drawMapPushButton_clicked():
void on_drawMapPushButton_clicked()
{
clearMap(); //Implementation is above
QPolygonF triangle1;
triangle1 << QPointF( 0 ,-1000) << QPointF(0 ,1000) << QPointF(1000, -1000);
drawTriangles(triangle1, Qt::black);
QPolygonF triangle2;
triangle2 << QPointF(-1000,-1000) << QPointF(-100,1000) << QPointF(-100,-1000);
drawTriangles(triangle2, Qt::red);
}
Map clearing function clearMap():
void clearMap()
{
if(mapEntity_){
delete mapEntity_;
mapEntity_ = nullptr;
mapEntity_ = new Qt3DCore::QEntity(view3dRootEntity_);
}
}
Ok here comes the extend answer.
The reason why this sometimes happens and sometimes not depends on the order of your entities. If you experiment with two simple spheres, one transparent and one not, you will see that when the sphere that is transparent is added later it will be drawn above the opaque object - just like you want it to.
This happens because the opaque object will be drawn first (it comes first in the scene graph) and the transparent object later which will give you the result you want. In the other case where the transparent object gets drawn first, the opaque object is drawn above because the QPhongAlphaMaterial has a QNoDepthMask render state which tells it not to write to the depth buffer. Thus, the opaque object always passes the depth test, where the transparent object actually already drew to. You have to do some more work to properly draw transparent objects for arbitrary scene graphs and camera positions.
The Qt3D Rendering Graph
To understand what you have to do you should understand how the Qt3D rendering graph is laid out. If you know this already you can skip this part.
Italic words reference items in the graph image in the following text.
If you use a Qt3DWindow, you can't access the root node of rendering graph. It is maintained by the window. You can access the QRenderSettings and root node of your framegraph through the functions activeFramegraph() and renderSettings() which you can both call on the window. You can also set the root node of scene graph through the setRootEntity() function of Qt3DWindow. The window internally has a QAspectEngine, where it sets the root node of the whole graph, which is the root node of the rendering graph in the graph image above.
If you want to insert a framegraph node to the existing framegraph of the 3D window, you have to add it as the parent of the active framegraph which I will explain in the next section. If you have your own custom framegraph which you set on the window through setActiveFramegraph() then just append it to the end, this should suffice.
Using QSortPolicy
As you already found out according to you other questions, you can use QSortPolicy in your framegraph to sort the entities by distance to camera. You can add a sort policy as follows (assuming that view is your Qt3DWindow and scene is your root entity of the scene graph, although I don't understand why it has to be):
Qt3DRender::QFrameGraphNode *framegraph = view.activeFrameGraph();
Qt3DRender::QSortPolicy *sortPolicy = new Qt3DRender::QSortPolicy(scene);
framegraph->setParent(sortPolicy);
QVector<Qt3DRender::QSortPolicy::SortType> sortTypes =
QVector<Qt3DRender::QSortPolicy::SortType>() << Qt3DRender::QSortPolicy::BackToFront;
sortPolicy->setSortTypes(sortTypes);
view.setActiveFrameGraph(framegraph);
The issue with this code is that this sort policy sorts the entities by the distance of their centers to the camera. If one of the opaque objects is closer to the camera than the transparent object it gets drawn later anyways and occludes the transparent object. See the images below for a graphical explanation.
The red and black sphere are further away from the camera than the torus, that's why they get drawn first and they don't occlude the torus.
No the center of the red sphere is closer to the camera than the center of the torus. It gets rendered later than the torus and occludes it.
Using Two Framegraph Branches
You can tackle the issue above if you use two framegraph branches. One which draws all opaque entities and one which draws all transparent ones. To achieve this you have to make use of QLayer and QLayerFilter. You can attach layers to entities and then add layer filters to your framegraph. This way you can exclude entities from entering a certain branch of your framegraph.
Let's say you create two layers, one for opaque objects and one for transparents ones:
Qt3DRender::QLayer *transparentLayer = new Qt3DRender::QLayer;
Qt3DRender::QLayer *opaqueLayer = new Qt3DRender::QLayer;
You have to attach the transparent layer to each transparent object and the opaque layer to each opaque object as a component (using addComponent()).
Unfortunately, you need a special framegraph tree to include the two corresponding layer filters (again, assuming that view is your Qt3DWindow):
Qt3DRender::QRenderSurfaceSelector *renderSurfaceSelector
= new Qt3DRender::QRenderSurfaceSelector();
renderSurfaceSelector->setSurface(&view);
Qt3DRender::QClearBuffers *clearBuffers
= new Qt3DRender::QClearBuffers(renderSurfaceSelector);
clearBuffers->setBuffers(Qt3DRender::QClearBuffers::AllBuffers);
clearBuffers->setClearColor(Qt::white);
This is the first branch to clear the buffers. Now you add the following code:
Qt3DRender::QViewport *viewport = new Qt3DRender::QViewport(renderSurfaceSelector);
Qt3DRender::QCameraSelector *cameraSelector = new Qt3DRender::QCameraSelector(viewport);
Qt3DRender::QCamera *camera = new Qt3DRender::QCamera(cameraSelector);
// set your camera parameters here
cameraSelector->setCamera(camera);
Since you create the QViewport as a child of the QRenderSurfaceSelector it is now a sibling in your framegraph with respect to the QClearBuffers. You can see an illustration of the example framegraphs here.
Now you have to create the two leaf nodes that contain the layer filters. The Qt3D engine always executes a whole branch when it reaches a leaf. This means that first the opaque objects are drawn and then the transparent ones.
// not entirely sure why transparent filter has to go first
// I would have expected the reversed order of the filters but this works...
Qt3DRender::QLayerFilter *transparentFilter = new Qt3DRender::QLayerFilter(camera);
transparentFilter->addLayer(transparentLayer);
Qt3DRender::QLayerFilter *opaqueFilter = new Qt3DRender::QLayerFilter(camera);
opaqueFilter->addLayer(opaqueLayer);
The two layer filters are now leaf nodes in your framegraph branch and Qt3D will first draw the opaque objects and then afterwards, since it uses the same viewport and everything, will draw the transparent objects above. It will draw them correctly (i.e. not in front of parts of opaque objects that the transparent object actually lies behind, because we did not clear the depth buffers again -> Splitting the framegraph happens only on the camera node).
Now set the new framegaph on your Qt3DWindow:
view.setActiveFrameGraph(renderSurfaceSelector);
Result:
Edit (26.03.21): As Patrick B. pointed out correctly, using the suggested solution with two layers you will have to add both layers as components to any lights in the scene. You can get around this by setting the filter mode on the QLayerFilters to QLayerFilter::FilterMode::DiscardAnyMatching and then reverse the order of the filters. This way, the transparentFilter discards any entities with the transparentLayer attached - but not the lights because they don't have the transparentLayer. Vice versa for the opaqueFilter.
My mistake was that i did wrong order of creating and deletion of Triangles and Sphere entities.
In pseudo code right order is as follows:
clearTriangles();
clearSphere();
drawTriangles();
drawSphere();
If you are using Qt3d with QML and want to control the order elements are drawn you can control it by the order of layers in your QML file.
Something like:
{
objectName: "firstLayer"
id : firstLayer
}
Layer {
objectName: "secondLayer"
id: secondLayer
}
The order you add them to layer filters will then control which is drawn first:
RenderSurfaceSelector {
CameraSelector {
id : cameraSelector
camera: mainCamera
FrustumCulling {
ClearBuffers {
buffers : ClearBuffers.AllBuffers
clearColor: "#04151c"
NoDraw {}
}
LayerFilter
{
objectName: "firstLayerFilter"
id: firstLayerFilter
layers: [firstLayer]
}
LayerFilter
{
id: secondLayerFilter
objectName: "secondLayerFilter"
layers: [secondLayer]
}
Then anything you add to the secondLayer will get drawn over-top of the first layer. I used this to make sure text always showed up in front of shapes, but it can be used similarly with transparencies.
I wanted to have an online monitoring system that could tell where the shape is currently, but am getting very weird coordinates of the item, also the dimensions of it get higher by 1 each time I create new one and drag it.
Initial position (map size is 751 by 751, checked by outputting to qDebug(), scene bound to yellow space) :
Dragging it to the left top corner.
As you can see in the beginning it was on (200;200), but after dragging it is on (-201;-196). After deleting it and creating new shape on the same position with the same properties, new shape can't be seen because it is outside of the map, which suggests that edits don't show correct data.
Here is the code of updating the edits:
void CallableGraphicsRectItem::mouseReleaseEvent(QGraphicsSceneMouseEvent* event)
{
QGraphicsRectItem::mouseReleaseEvent(event);
ptr->updateEdits(this);
}
Here is what I managed to cut down into updateEdits():
void MainWindow::updateEdits(QAbstractGraphicsShapeItem* item)
{
//stuff not related to scene
auto posReal = item->scenePos();
auto pos = posReal.toPoint();
//create QString from coordinates
QString coordinate;
coordinate.setNum(pos.x());
ui->leftXEdit->setText(coordinate);
coordinate.setNum(pos.y());
ui->upperYEdit->setText(coordinate);
//get width and height for rect, radius for circle
auto boundingRectReal = item->sceneBoundingRect();
auto boundingRect = boundingRectReal.toRect();
ui->widthEdit->setText(QString::number(boundingRect.width()));
//disables height edit for circles, not really relevant
if (!items[currentShapeIndex].isRect)
{
ui->heightEdit->setDisabled(true);
}
else
{
ui->heightEdit->setDisabled(false);
ui->heightEdit->setText(QString::number(boundingRect.height()));
}
}
Here is how I anchor the QGraphicsScene to the left top corner of the yellow area:
scene->setSceneRect(0, 0, mapSize.width() - 20, mapSize.height() - 20);
ui->graphicsView->setScene(scene);
How can I report the right data to the edits?
You're better off overriding the itemChange method and using the ItemPositionHasChanged notification. You have to set the ItemSendsGeometryChanges flag on the item so that it receives these notifications.
I'm not sure that your item's final position has been set when you're still in the mouseReleaseEvent method. Tracking it in itemChange will ensure that the data is valid, and this kind of thing is what it's for.
Also, note that "pos" is in the item's parent coordinates, and "boundingRect" is in the item's coordinate space. You should use "scenePos" and "sceneBoundingRect" if you want to be sure you're using scene coordinates. If the item doesn't have a parent, then "pos" and "scenePos" will return the same values, but "boundingRect" and "sceneBoundingRect" will generally differ.
The title says it pretty much all:
I have two screens, and each time I create a QDialog it appears in the same screen as its parent.
How can I make it appear in a different screen? Or should I use a different type of top-level widget?
The code I use to create the dialog is:
QDialog my_dialog = new QDialog(this,
Qt::WindowMaximizeButtonHint |
Qt::WindowCloseButtonHint);
...
EDIT:
I have also tried using the QDesktopWidget which gives me a QScreen object that refers to the second screen. But then I don't find how to instruct the QDialog to use that QScreen (setting it as the parent doesn't work).
It is bad, that you edit your question without reading comments :(
// Your screen geometry:
QRect buildScreenGeometry()
{
auto desktop = QApplication::desktop();
QRect virtualRect;
const auto n = desktop->screenCount();
for ( auto i = 0; i < n; i++ )
virtualRect |= desktop->screenGeometry(i);
return virtualRect;
}
// Moving
auto dlg = new QDialog( someParent );
auto newPoint = QPoint( 2000, 0 ); // point on another screen
auto realPos = someParent->mapFromGlobal( newPoint );
dlg->move( realPos );
That's all.
UPDATE:
You should understand, that there are only ONE screen area with COMMON coordinate system, that contains ALL screens.
For example, you have 2 monitors with 800x600 resolution. First (main) monitor is standing left, and second standing right. In this case, coordinate system, that is available for your application is 1600x600. So, if your widget has 100x100 top-left position, on a first monitor, and you want to move it to another, you should call move(900x100); // 900 == screen1.width() + dialog.pos().x(). Then your widget will have 100x100 position on second monitor.
You should read Qt documentation.
You can use move on your QDialog, but be aware that move will set the QDialog position relative to it's parent.
You can get the Main Window's screen position and use that to setup the QDialog position. Just know that you're not guaranteed to have 2 screens on the end user machine.
For more information on move see: http://doc.qt.io/qt-5/application-windows.html#window-geometry