QPlaneMesh 上不透明度 = 0 QTextureMaterial 的 Qt3d svg 或 png 纹理

Question

我尝试将包含 opacity=0 区域的 svg 图像添加到 QPlaneMesh 上的 QTextureMaterial 中，但它显示平面的背景始终为灰色。

我希望飞机可以控制我的图像并穿透到 opacity=0 区域中的其他对象。

像https://image.flaticon.com/icons/svg/3154/3154348.svg这样的svg文件。

代码：

// Background
        Qt3DCore::QEntity *planeEntity = new Qt3DCore::QEntity(rootEntity);
        Qt3DExtras::QPlaneMesh *planeMesh = new Qt3DExtras::QPlaneMesh(planeEntity);
        planeMesh->setHeight(2);
        planeMesh->setWidth(2);

        Qt3DExtras::QTextureMaterial *planeMaterial = new Qt3DExtras::QTextureMaterial(planeEntity);
        Qt3DRender::QTexture2D *planeTexture = new Qt3DRender::QTexture2D(planeMaterial);
        FlippedTextureImage *planeTextureImage = new FlippedTextureImage(planeTexture);
        planeTextureImage->setSize(QSize(3507, 3000));
        planeTexture->addTextureImage(planeTextureImage);
        planeMaterial->setTexture(planeTexture);

        Qt3DCore::QTransform *planeTransform = new Qt3DCore::QTransform(planeEntity);
        planeTransform->setRotationX(90);
        planeTransform->setTranslation(QVector3D(0, 0, 0));

        Qt3DExtras::QPhongAlphaMaterial *pam2 = new Qt3DExtras::QPhongAlphaMaterial(planeEntity);
        pam2->setAlpha(0);

        planeEntity->addComponent(planeMesh);
        planeEntity->addComponent(pam2);
        planeEntity->addComponent(planeMaterial);
        planeEntity->addComponent(planeTransform);

class FlippedTextureImage : public Qt3DRender::QPaintedTextureImage
{
public:
    FlippedTextureImage(Qt3DCore::QNode *parent = Q_NULLPTR):Qt3DRender::QPaintedTextureImage(parent) {}
    void paint(QPainter *painter) override {
        QSvgRenderer renderer(QString(qApp->applicationDirPath() + "/gift.svg"));
        QImage image(3000, 3000, QImage::Format_RGBA64);  // 512x512 RGBA
        image.fill(0x00ffffff);                           // white background
        QPainter painter2(&image);
        renderer.render(&painter2);
        painter->drawImage(0, 0, image);
    }
};

and run code like this

Answer 1

QTextureMaterial 不支持纹理中的透明度。

查看my answer to this question，了解如何自己在纹理中实现透明度。 Qt3D 中没有开箱即用的解决方案。