QT3D中的2D网格 [英] 2D meshes in QT3D

问题描述

在我看来Qt3D无法很好地渲染2D网格.要了解我的意思，请打开阴影地图QML示例并将摄像头控制器从FirstPersonCameraController更改为OrbitCameraController.运行程序并尝试从下面查看地平面，您将看到它消失.因此QT3D只是从一侧渲染2D网格，并从另一侧渲染透明.

It seems to me that Qt3D cannot render 2D meshes well. To see what I mean open the shadow map QML example and change the camera controller from FirstPersonCameraController to OrbitCameraController. Run the program and attempt to view the ground plane from below, you will see it disappear. So QT3D just renders 2D meshes from one side and makes them transparent from the other side.

我该如何解决?即从两侧渲染2D网格?

How can I fix this? i.e. render 2D meshes from both sides?

现在，我知道必须禁用剔除才能使渲染正常工作.我想到了这一点:

Now I know that I have to disable culling for the rendering to work. I came up to this point:

//'this' refers to Qt3DWindow
rootEntity->addComponent(this->renderSettings());
QCullFace *face = new QCullFace();
QRenderStateSet *stateSet = new QRenderStateSet(this->renderSettings()->activeFrameGraph());
QRenderSurfaceSelector *selector = new QRenderSurfaceSelector(this->renderSettings());
face->setMode(QCullFace::NoCulling);
stateSet->addRenderState(face);
selector->setSurface(this);

但是这似乎并没有改变任何东西.我想念什么吗?

but this still doesn't seem to change anything. Am I missing something?

推荐答案

这是一个最低限度的示例:

Here is a minimally working example:

main.cpp:

#include <QApplication>
#include "clickwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    GraphicsWindow graphicsWindow;
    graphicsWindow.show();
    return a.exec();
}

graphicswindow.h:

#include <Qt3DExtras/Qt3DWindow>
#include <Qt3DCore/QEntity>
#include <Qt3DCore/QTransform>

class GraphicsWindow : public Qt3DExtras::Qt3DWindow {
public:
    GraphicsWindow();
    void wheelEvent ( QWheelEvent * event ) override;

private:
    Qt3DCore::QEntity *createScene();
    Qt3DCore::QTransform *planeTransform;
};

graphicswindow.cpp:

#include "graphicswindow.h"
#include <QMouseEvent>
#include <Qt3DRender/QViewport>
#include <Qt3DRender/QClearBuffers>
#include <Qt3DRender/QRenderSurfaceSelector>
#include <Qt3DRender/QRenderStateSet>
#include <Qt3DRender/QCullFace>
#include <Qt3DRender/QCameraSelector>
#include <Qt3DRender/QCamera>
#include <Qt3DRender/QMaterial>
#include <Qt3DExtras/QGoochMaterial>
#include <Qt3DExtras/QPlaneMesh>
#include <Qt3DRender/QDepthTest>

GraphicsWindow::GraphicsWindow() : Qt3DExtras::Qt3DWindow() {
    Qt3DRender::QCamera *camera = this->camera();
    camera->lens()->setPerspectiveProjection(45.0f, 16.0f/9.0f, 0.1f, 1000.0f);
    camera->setPosition(QVector3D(20.0, 20.0, 20.0f));
    camera->setViewCenter(QVector3D(0, 0, 0));

    Qt3DRender::QRenderSurfaceSelector *surfaceSelector = new Qt3DRender::QRenderSurfaceSelector;
    surfaceSelector->setSurface(this);
    Qt3DRender::QViewport *viewport = new Qt3DRender::QViewport(surfaceSelector);
    viewport->setNormalizedRect(QRectF(0, 0, 1.0, 1.0));
    Qt3DRender::QCameraSelector *cameraSelector = new Qt3DRender::QCameraSelector(viewport);
    cameraSelector->setCamera(camera);
    Qt3DRender::QClearBuffers *clearBuffers = new Qt3DRender::QClearBuffers(cameraSelector);
    clearBuffers->setBuffers(Qt3DRender::QClearBuffers::ColorDepthBuffer);
    clearBuffers->setClearColor(Qt::white);
    Qt3DRender::QRenderStateSet *renderStateSet = new Qt3DRender::QRenderStateSet(clearBuffers);
    Qt3DRender::QCullFace *cullFace = new Qt3DRender::QCullFace(renderStateSet);
    cullFace->setMode(Qt3DRender::QCullFace::NoCulling);
    renderStateSet->addRenderState(cullFace);
    Qt3DRender::QDepthTest *depthTest = new Qt3DRender::QDepthTest;
    depthTest->setDepthFunction(Qt3DRender::QDepthTest::Less);
    renderStateSet->addRenderState(depthTest);
    setActiveFrameGraph(surfaceSelector);

    Qt3DCore::QEntity *root = createScene();
    setRootEntity(root);
}

void GraphicsWindow::wheelEvent(QWheelEvent *event) {
    planeTransform->setRotationZ(planeTransform->rotationZ() + event->delta() / 40.f);
}


Qt3DCore::QEntity* GraphicsWindow::createScene() { // Root entity
    Qt3DCore::QEntity *rootEntity = new Qt3DCore::QEntity;

    Qt3DCore::QEntity *planeEntity = new Qt3DCore::QEntity(rootEntity);
    Qt3DRender::QMaterial *meshMaterial = new Qt3DExtras::QGoochMaterial;
    Qt3DExtras::QPlaneMesh *planeMesh = new Qt3DExtras::QPlaneMesh;
    planeMesh->setHeight(10);
    planeMesh->setWidth(10);
    planeTransform = new Qt3DCore::QTransform;

    planeEntity->addComponent(planeTransform);
    planeEntity->addComponent(planeMesh);
    planeEntity->addComponent(meshMaterial);

    return rootEntity;
}

请记住，Qt3DWindow的setActiveFramegraph功能会自动将由窗口的renderSettings()功能返回的QRenderSettings添加到您设置为活动框架图的框架图节点上.如果要实现自己的3D窗口或创建并提供屏幕外渲染器，则必须使用QRenderSettings作为框架图的根节点(该窗口将其渲染设置设置为您设置的根框架图节点的父节点)，并添加将设置渲染到实际的根节点，即该节点是框架图和场景图的父级.

Keep in mind that the setActiveFramegraph function of the Qt3DWindow automatically adds the QRenderSettings returned by the renderSettings() function of the window on the frame graph node that you set as the active frame graph. If you are implementing your own 3D window or create and offscreen renderer you have to use QRenderSettings as the root node of your framegraph (the window sets its render settings as the parent of the root frame graph node that you set) and add the render settings to the actual root node, i.e. the node that is the parent of the frame graph and the scene graph.

这篇关于QT3D中的2D网格的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！