- Qt 6.7
- Qt Quick 3D
- Qt Quick 3D Examples and Tutorials
- Qt Quick 3D - Instanced Rendering Example
- Qt Quick 3D | Commercial or GPLv3

# Qt Quick 3D - Instanced Rendering Example

Demonstrates how to do instanced rendering in Qt Quick 3D.

This example shows how do instanced rendering using the basic QML API.

The spaceship and asteroid models were created using the Blender 3D modeling tool, and imported with balsam.

#### Random instancing

We use RandomInstancing to make a random table that defines our asteroid field:

     RandomInstancing {
         id: randomInstancing
         instanceCount: 1500

         position: InstanceRange {
             from: Qt.vector3d(-300, -200, -500)
             to: Qt.vector3d(300, 200, 200)
         }
         scale: InstanceRange {
             from: Qt.vector3d(1, 1, 1)
             to: Qt.vector3d(10, 10, 10)
             proportional: true
         }
         rotation: InstanceRange {
             from: Qt.vector3d(0, 0, 0)
             to: Qt.vector3d(360, 360, 360)
         }
         color: InstanceRange {
             from: "grey"
             to: "white"
             proportional: true
         }

         randomSeed: 2021
     }

Position and rotation are allowed to vary freely. Scaling is set to be uniform in all directions and colors are grayscale. This is done by setting the proportional attribute.

The spaceships are placed manually using InstanceList:

     InstanceListEntry {
         id: redShip
         position: Qt.vector3d(50, 10, 100)
         eulerRotation: Qt.vector3d(0, 180, 0)
         color: "red"
         NumberAnimation on position.x {
             from: 50
             to: -70
             duration: 8000
         }
     }

     InstanceListEntry {
         id: greenShip
         position: Qt.vector3d(0, 0, -60)
         eulerRotation: Qt.vector3d(-10, 0, 30)
         color: "green"
     }

     InstanceListEntry {
         id: blueShip
         position: Qt.vector3d(-100, -100, 0)
         color: "blue"
     }

     InstanceList {
         id: manualInstancing
         instances: [ redShip, greenShip, blueShip ]
     }

The properties of InstanceListEntry are bindable: here we animate the red ship so it crosses the path of the camera.

Finally we apply the instancing tables to the objects:

     Asteroid {
         instancing: randomInstancing
         NumberAnimation on eulerRotation.x {
             from: 0
             to: 360
             duration: 11000
             loops: Animation.Infinite
         }
     }

     SimpleSpaceship {
         instancing: manualInstancing
     }

By animating the rotation of the asteroid model, all of the instances will rotate without having to change the contents of the instance table. Since the asteroid instances have random rotations, all the asteroids will rotate around different axes.

Files:

- instancing/Asteroid.qml
- instancing/CMakeLists.txt
- instancing/Example/Asteroid.qml
- instancing/Example/SimpleSpaceship.qml
- instancing/Example/instancing_qml_module_dir_map.qrc
- instancing/Example/main.qml
- instancing/Example/qmldir
- instancing/SimpleSpaceship.qml
- instancing/instancing.pro
- instancing/main.cpp
- instancing/main.qml
- instancing/qml.qrc