变焦Qt3D相机

Question

如何为Qt3D Camera的FOV实现双指捏手势处理？

有FirstPersonCameraController和OrbitCameraController摄像头控制器来处理鼠标/触控板事件。后者甚至有zoomLimit属性，但它的意思不是我需要放大场景(从一个立方体地图中，相机的位置固定到(0, 0, 0))。我用的是前一个。它正确地处理鼠标拖动和单指触摸事件，但不处理两指捏式手势。

我可以用简单的方式定制PinchArea来与Qt3D的Camera交互吗？或者Quick在这个意义上与Qt3D的API是正交的？

Answer 1

使用pinchUpdated事件PinchArea查找有关夹点的信息:根据文档

夹点参数提供关于夹点手势的信息，包括夹点的比例、中心和角度。这些值仅反映自当前手势开始以来的更改，因此不受夹点属性中的最小和最大限制的限制。

所以你应该可以这样做：

Camera {
    id: myCamera
}

PinchArea {
    onPinchUpdated: {
        myCamera.fieldOfView = pinch.scale*someFactor
    } 
}

这可以在任何定制的QML中完成，您可以访问夹点和相机。如果是自定义脚本，则可以将摄像机作为属性传递给阿尔瓦兹。

property Camera myCamera

Answer 2

最后我把PinchArea和MouseArea结合在一起

import QtQml 2.2

import QtQuick 2.9
import QtQuick.Scene3D 2.0

import Qt3D.Core 2.9
import Qt3D.Extras 2.9
import Qt3D.Render 2.9
import Qt3D.Input 2.1
import Qt3D.Logic 2.0

import PanoEntity 1.0
import Utility 1.0

Item {
    property url panorama
    onPanoramaChanged: {
        if (panorama.toString().length !== 0) {
            if (panoEntity.setPanorama(panorama)) {
                basicCamera.position = Qt.vector3d(0.0, 0.0, 0.0)
                basicCamera.upVector = Qt.vector3d(0.0, 0.0, 1.0)
                basicCamera.viewCenter = panoEntity.pano.dir
                pinchArea.updateFov(defaultFov)
            }
        }
    }

    property Image previewImage

    property real fovMin: 20.0
    property real defaultFov: 60.0
    property real fovMax: 90.0

    property real sensitivity: 1.5
    property real pinchSensitivity: 0.5

    Scene3D {
        id: scene3d

        anchors.fill: parent

        aspects: ["render", "input", "logic"]
        cameraAspectRatioMode: Scene3D.AutomaticAspectRatio // basicCamera.aspectRatio = width / height
        multisample: true

        Entity {
            Camera {
                id: basicCamera

                projectionType: CameraLens.PerspectiveProjection
                nearPlane: 0.1
                farPlane: 2.0 * Math.SQRT2
            }

            RenderSettings {
                id: renderSettings

                renderPolicy: scene3d.visible ? RenderSettings.Always : RenderSettings.OnDemand

                ForwardRenderer {
                    camera: basicCamera

                    clearColor: "transparent"
                }
            }

            InputSettings {
                id: inputSettings
            }

            components: [renderSettings, inputSettings]

            PanoEntity {
                id: panoEntity

                MemoryBarrier {
                    waitFor: MemoryBarrier.All
                }
            }
        }
    }
    PinchArea {
        id: pinchArea

        anchors.fill: parent

        function updateFov(newFov) {
            if (newFov > fovMax) {
                newFov = fovMax
            } else if (newFov < fovMin) {
                newFov = fovMin
            }
            var eps = 1.0 / 60.0
            if (Math.abs(basicCamera.fieldOfView - newFov) > eps) {
                basicCamera.fieldOfView = newFov
                zoomer.fov = newFov
            }
        }

        function updatePinch(pinch) {
            updateFov(basicCamera.fieldOfView * (1.0 + (pinch.previousScale - pinch.scale) * pinchSensitivity))
        }

        onPinchUpdated: {
            updatePinch(pinch)
        }
        onPinchFinished: {
            updatePinch(pinch)
        }

        MouseArea {
            anchors.fill: parent

            propagateComposedEvents: true

            property point startPoint

            function updateView(mouse) {
                basicCamera.pan((startPoint.x - mouse.x) * sensitivity * basicCamera.fieldOfView / width, Qt.vector3d(0.0, 0.0, 1.0))
                basicCamera.tilt((mouse.y - startPoint.y) * sensitivity * basicCamera.fieldOfView / height)
                startPoint = Qt.point(mouse.x, mouse.y)
            }

            onPressed: {
                startPoint = Qt.point(mouse.x, mouse.y)
            }
            onPositionChanged: {
                updateView(mouse)
            }
            onReleased: {
                updateView(mouse)
            }
        }
    }
    Zoomer {
        id: zoomer

        fovMax: parent.fovMax
        defaultFov: parent.defaultFov
        fovMin: parent.fovMin

        anchors.horizontalCenter: parent.horizontalCenter
        anchors.bottom: parent.bottom
        anchors.bottomMargin: 45

        onFovChanged: {
            pinchArea.updateFov(fov);
        }
    }

    Shortcut {
        context: Qt.WindowShortcut
        enabled: scene3d.visible

        sequence: StandardKey.Save

        onActivated: {
            panoEntity.pano.dir = basicCamera.viewCenter
            panoEntity.pano.up = basicCamera.upVector
            panoEntity.pano.version = 7
            if (!panoEntity.updatePanorama()) {
                console.log("Unable to update panorama %1".arg(panorama))
            } else if (previewImage && Utility.fileExists(previewImage.source)) {
                scene3d.grabToImage(function(grabResult) {
                    if (!grabResult.saveToFile(Utility.toLocalFile(previewImage.source))) {
                        console.log("Unable save preview to file: %1".arg(previewImage.source))
                    }
                }, Qt.size(512, 512))
            }
        }
    }
}