Qt Quick 3D Physics - Cannon Example

Demonstrates how to spawn physical objects.

This example demonstrates how to create and delete physical objects on demand. The scene consists of a number of stacks of boxes. You can move around by using WASD and the mouse and shoot a ball by pressing space.

The scene is setup with the usual Qt Quick 3D objects like view, camera and light:

 PerspectiveCamera {
     id: camera
     position: Qt.vector3d(-4000, 5000, 10000)
     eulerRotation: Qt.vector3d(-20, -20, 0)
     clipFar: 500000
     clipNear: 100
 }
 DirectionalLight {
     eulerRotation: Qt.vector3d(-45, 45, 0)
     castsShadow: true
     brightness: 1
     shadowMapQuality: Light.ShadowMapQualityVeryHigh
     shadowFactor: 100
 }

We also add a static floor:

 StaticRigidBody {
     eulerRotation: Qt.vector3d(-90, 0, 0)
     collisionShapes: PlaneShape {}
     Model {
         source: "#Rectangle"
         scale: Qt.vector3d(2000, 2000, 1)
         materials: PrincipledMaterial {
             baseColor: "green"
         }
         castsShadows: false
         receivesShadows: true
     }
 }

We create a Node we use as the spawner of objects and put inside our view:

 Node {
     id: shapeSpawner
     property var instancesBoxes: []
     property var instancesSpheres: []
     property int stackCount: 0
     property var boxComponent: Qt.createComponent("Box.qml")
     property var sphereComponent: Qt.createComponent("Sphere.qml")

     function createStack(stackZ, numStacks) {
         let size = 10
         let extents = 400

         for (var i = 0; i < size; i++) {
             for (var j = 0; j < size - i; j++) {
                 let x = j * 2 - size + i
                 let y = i * 2 + 1
                 let z = 5 * (stackZ - numStacks)
                 let center = Qt.vector3d(x, y, z).times(0.5 * extents)
                 let box = boxComponent.incubateObject(shapeSpawner, {
                                                           "position": center,
                                                           "xyzExtents": extents
                                                       })
                 instancesBoxes.push(box)
             }
         }
     }

     function createBall(position, forward) {
         var diameter = 600
         var speed = 20000
         let settings = {
             "position": position,
             "sphereDiameter": diameter
         }
         let sphere = sphereComponent.createObject(shapeSpawner, settings)
         sphere.setLinearVelocity(forward.times(speed))
         instancesSpheres.push(sphere)

         if (sphere === null) {
             console.log("Error creating object")
         }
     }

     function reset() {
         // Only run method if previous stack has been created fully
         for (var i = 0; i < instancesBoxes.length; i++)
             if (!instancesBoxes[i].object)
                 return

         instancesSpheres.forEach(sphere => {
                                      sphere.collisionShapes = []
                                      sphere.destroy()
                                  })
         instancesBoxes.forEach(box => {
                                    box.object.collisionShapes = []
                                    box.object.destroy()
                                })
         instancesSpheres = []
         instancesBoxes = []

         for (var stackI = 0; stackI < stackSlider.value; stackI++) {
             shapeSpawner.createStack(stackI, stackSlider.value)
         }
     }
 }

We have three methods: createStack for creating a stack, createBall for creating a ball with velocity and reset for resetting the scene. The actual box and sphere that is spawn is stored in their own qml files (box.qml and sphere.qml).

Files: