- Qt 6.8
- Qt Quick 3D
- Qt Quick 3D Examples and Tutorials
- Qt Quick 3D - XR Spatial Anchors Example
- Qt Quick 3D | Commercial or GPLv3

# Qt Quick 3D - XR Spatial Anchors Example

Demonstrates how to use spatial anchors in Qt Quick 3D XR.

This example shows how to use XrSpatialAnchorListModel to display and interact with real physical objects in the environment. It supports both passthrough mode and fully immersive mode. The basic structure follows the xr_simple example.

The most relevant part of the example is a Repeater3D on an XrSpatialAnchorListModel. For each anchor, we create a box that fills the volume of the anchor with a color. The choice of color depends on the classification of the anchor. This box is invisible in passthrough mode. In addition, we visualize the position and orientation of the anchor with small boxes:

     Repeater3D {
         id: spatialAnchors
         model: XrSpatialAnchorListModel {
         }
         delegate: Node {
             id: anchorNode
             required property XrSpatialAnchor anchor
             required property int index
             position: anchor.position
             rotation: anchor.rotation

             Model {
                 pickable: true
                 z: anchorNode.anchor.has3DBounds ? anchorNode.anchor.offset3D.z / 2 * 100 : 0 // Position is center of 2D surface also for 3D anchors
                 scale: anchorNode.anchor.has3DBounds ? anchorNode.anchor.extent3D : Qt.vector3d(anchorNode.anchor.extent2D.x, anchorNode.anchor.extent2D.y, 0.01)
                 materials: PrincipledMaterial {
                     // Make anchor objects invisible in passthrough mode
                     baseColor: xrView.passthroughEnabled ? Qt.rgba(0, 0, 0, 0) : anchorColor(anchor)
                     alphaMode: xrView.passthroughEnabled ? PrincipledMaterial.Blend : PrincipledMaterial.Opaque
                     roughness: 0.7
                 }
                 source: anchorNode.anchor.has3DBounds ? "#Cube" : "#Rectangle"
                 property string anchorInfo: "anchor #" + anchorNode.index + ", " + anchorNode.anchor.classificationString
             }

             Model {
                 // Visualize anchor orientation
                 materials: PrincipledMaterial {
                     baseColor: anchorNode.anchor.has3DBounds ? anchorNode.anchor.has2DBounds ? "green" : "red" : "blue"
                 }
                 scale: Qt.vector3d(0.05, 0.05, 0.05)
                 source: "#Cube"

                 Model {
                     materials: PrincipledMaterial {
                         baseColor: "black"
                     }
                     scale: Qt.vector3d(0.1, 3, 0.1)
                     source: "#Cube"
                     y: 150
                 }
                 Model {
                     materials: PrincipledMaterial {
                         baseColor: "white"
                     }
                     scale: Qt.vector3d(3, 0.1, 0.1)
                     source: "#Cube"
                     x: 150
                 }
             }
             visible: anchor.has2DBounds || anchor.has3DBounds
         }
     }

The box for the anchor is pickable and has a string property `anchorInfo` that contains the classificationString of the anchor. We then perform picking based on the controller's position. (See the xr_input example for details.) If we hit one of the anchor boxes, we show a label with the anchor information:

     Node {
         id: labelNode
         position: rightController.position
         rotation: rightController.rotation

         property int numAnchors: spatialAnchors.count
         property string anchorInfo: "(no anchor)"

         Node {
             y: 15
             x: -15
             scale: Qt.vector3d(0.1, 0.1, 0.1)
             Rectangle {
                 width: 300
                 height: 100
                 color: Qt.rgba(1,0.9,0.8,0.7)
                 radius: 10
                 border.width: 2
                 border.color: "blue"
                 Text {
                     anchors.fill: parent
                     anchors.margins: 10
                     textFormat: Text.StyledText
                     text: "Total anchors: " + labelNode.numAnchors + "<br>" + "Selected: " + labelNode.anchorInfo
                 }
             }
         }
     }

Example project @ code.qt.io