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, 0)
         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

     function createStack(stackZ) {
         var size = 10;
         var extents = 400;

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

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

     function createBall(position, forward) {
         var diameter = 600;
         var speed = 20000;
         var component = Qt.createComponent("sphere.qml");
         let sphere = component.createObject(shapeSpawner, {position: position, linearVelocity: forward.times(speed), sphereDiameter: diameter});
         instancesSpheres.push(sphere);

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

     function reset() {
         instancesSpheres.forEach(sphere => { sphere.destroy(); });
         instancesBoxes.forEach(boxes => { boxes.destroy(); });
         instancesSpheres = [];
         instancesBoxes = [];

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

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: