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++ // Copyright (C) 2025 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
++ import QtQuick
++ import QtQuick3D
++
++ // The rotation math is based on the paper
++ // ARCBALL:
++ // A User Interface for Specifying Three-Dimensional Orientation Using a Mouse
++ // by Ken Shoemake, 1992
++ Item {
++ id: root
++
++ implicitWidth: parent.width
++ implicitHeight: parent.height
++ focus: true
++
++ required property Node controlledObject
++ required property Camera camera
++
++ property real zoomSpeed: 0.1
++ property real pinchSpeed: 1.0
++
++ property vector3d lastPos: Qt.vector3d(0, 0, 0)
++ property bool moving: false
++
++ // From Shoemake 1992:
++ // pt.x <- (screen.x - center.x)/radius;
++ // pt.y <- (screen.y - center.y)/radius;
++ // r <- pt.x*pt.x + pt.y*pt.y;
++ // IF r > 1.0
++ // THEN s <- 1.0/Sqrt[r];
++ // pt.x <- s*pt.x;
++ // pt.y <- s*pt.y;
++ // pt.z <- 0.0;
++ // ELSE pt.z <- Sqrt[1.0 - r] ;
++ function pos2DToPos3D(posNDC) {
++ var pt = Qt.vector3d(posNDC.x, posNDC.y, 0)
++ let r = posNDC.x * posNDC.x + posNDC.y * posNDC.y
++ if (r > 1.0) {
++ let s = 1.0 / Math.sqrt(r)
++ pt.x = s * pt.x
++ pt.y = s * pt.y
++ pt.z = 0.0
++ } else {
++ pt.z = Math.sqrt(1.0 - r)
++ }
++
++ return pt
++ }
++
++ function screenToNDC(pos) {
++ return Qt.vector2d((2.0 * pos.x - width) / width,
++ (height - 2.0 * pos.y) / height)
++ }
++
++ function mousePressed(pos) {
++ lastPos = pos2DToPos3D(screenToNDC(pos))
++ moving = true
++ }
++
++ function mouseReleased() {
++ moving = false
++ }
++
++ function mouseMoved(pos) {
++ if (!moving)
++ return
++
++ let currentPos = pos2DToPos3D(screenToNDC(pos))
++
++ // From Shoemake 1992:
++ // [q.x, q.y, q.z] <- V3_Cross[pO, p1];
++ // q.w <- V3_Dot[pO, p1];
++ // qnow <- QuatMul[q, qstart];
++ let p0 = lastPos
++ let p1 = currentPos
++ let p0p1 = p0.crossProduct(p1)
++ let q = Qt.quaternion(p0.dotProduct(p1), p0p1.x, p0p1.y, p0p1.z)
++ let qnow = q.times(controlledObject.rotation)
++ controlledObject.rotation = qnow
++ lastPos = currentPos
++ }
++
++ DragHandler {
++ target: null
++ enabled: true
++ acceptedModifiers: Qt.NoModifier
++
++ onActiveChanged: {
++ if (active)
++ root.mousePressed(centroid.position)
++ else
++ root.mouseReleased()
++ }
++
++ onCentroidChanged: {
++ root.mouseMoved(centroid.position)
++ }
++ }
++
++ PinchHandler {
++ target: null
++ enabled: true
++
++ onScaleChanged: delta => {
++ root.camera.z *= 1.0 / (delta * root.pinchSpeed)
++ }
++ }
++
++ WheelHandler {
++ target: null
++ enabled: true
++ orientation: Qt.Vertical
++ acceptedDevices: PointerDevice.Mouse | PointerDevice.TouchPad
++
++ onWheel: event => {
++ let delta = -event.angleDelta.y * 0.01
++ root.camera.z += root.camera.z * delta * root.zoomSpeed
++ }
++ }
++
++ TapHandler {
++ onTapped: root.forceActiveFocus()
++ }
++ }