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:

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