- Qt 6.4
- Qt Quick 3D Physics
- Qt Quick 3D Physics Examples and Tutorials
- Qt Quick 3D Physics - Compound Shapes Example
- Qt Quick 3D Physics | Commercial or GPLv3

# Qt Quick 3D Physics - Compound Shapes Example

Demonstrates using complex collision shapes.

This example demonstrates how to use more than one collision shape to create complex objects for collision detection. The scene consists of a green static plane and a series of links connected to each other. At the beginning, the simulation is disabled. After some time or when the user press the space key, the simulation will start. An animation will start that causes the leftmost link to move horizontally. Since the leftmost link is purely controlled by animation, the isKinematic property is set to true.

#### Setup

As usual we need to add our DynamicsWorld:

     DynamicsWorld {
         id: physicsWorld
         running: false
         enableCCD: true
     }

We do the usual setup where we have an environment, camera and lights:

     environment: SceneEnvironment {
         antialiasingMode: SceneEnvironment.MSAA
         backgroundMode: SceneEnvironment.Color
         clearColor: "lightblue"
     }

     focus: true

     PerspectiveCamera {
         id: camera
         position: Qt.vector3d(-200, 900, 1300)
         eulerRotation: Qt.vector3d(-10, 0, 0)
         clipFar: 15500
         clipNear: 1
     }

     DirectionalLight {
         eulerRotation.x: -45
         eulerRotation.y: 45
         castsShadow: true
         brightness: 1.5
         shadowFactor: 15
         shadowFilter: 10
         shadowMapFar: 100
         shadowBias: -0.01
         shadowMapQuality: Light.ShadowMapQualityVeryHigh
     }

#### Physical objects

We have our regular static plane:

     StaticRigidBody {
         position: Qt.vector3d(0, -100, 0)
         eulerRotation: Qt.vector3d(-90, 0, 0)
         collisionShapes: PlaneShape {}
         Model {
             source: "#Rectangle"
             scale: Qt.vector3d(500, 500, 0)
             materials: DefaultMaterial {
                 diffuseColor: "green"
             }
             castsShadows: false
             receivesShadows: true
         }
     }

Then we make instances of our links.

     MeshLink {
         isKinematic: true
         position: Qt.vector3d(-6 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
         color: "red"

         SequentialAnimation on x {
             running: physicsWorld.running
             PauseAnimation {
                 duration: 7000
             }
             NumberAnimation {
                 from: -6 * viewport.ringDistance
                 to: -9 * viewport.ringDistance
                 duration: 3000
                 easing.type: Easing.InOutQuad
             }

             SequentialAnimation {
                 NumberAnimation {
                     from: -9 * viewport.ringDistance
                     to: 3 * viewport.ringDistance
                     easing.type: Easing.InOutCubic
                     duration: 8000
                 }
                 NumberAnimation {
                     to: -9 * viewport.ringDistance
                     from: 3 * viewport.ringDistance
                     easing.type: Easing.InOutCubic
                     duration: 8000
                 }
                 loops: Animation.Infinite
             }
         }
     }

     CapsuleLink {
         position: Qt.vector3d(-5 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
     }

     MeshLink {
         position: Qt.vector3d(-4 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
     }

     MeshLink {
         position: Qt.vector3d(-3 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(0, 90, 0)
     }

     MeshLink {
         position: Qt.vector3d(-2 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
     }

     MeshLink {
         position: Qt.vector3d(-1 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(0, 90, 0)
     }

     CapsuleLink {
         position: Qt.vector3d(0, viewport.ringY, 0)
     }

     MeshLink {
         position: Qt.vector3d(1 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(0, 90, 0)
     }

     MeshLink {
         position: Qt.vector3d(2 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
     }

     MeshLink {
         position: Qt.vector3d(3 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(0, 90, 0)
     }

     MeshLink {
         position: Qt.vector3d(4 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
     }

     CapsuleLink {
         position: Qt.vector3d(5 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
     }

     MeshLink {
         isKinematic: true
         position: Qt.vector3d(6 * viewport.ringDistance, viewport.ringY, 0)
         eulerRotation: Qt.vector3d(90, 0, 0)
         color: "red"
     }

The first link which is on the left has its isKinematic property set to true so that we can control it via animation. The other links are instanced with some spacing between them.

The interesting part is what is happening inside the Mesh and Capsule Links files. Let's take a look at each one of them.

#### Mesh Link

     DynamicRigidBody {
         scale: Qt.vector3d(100, 100, 100)
         property color color: "white"
         PrincipledMaterial {
             id: _material
             baseColor: color
             metalness: 1.0
             roughness: 0.5
         }

         Model {
             source: "meshes/ring.mesh"
             materials: [
                 _material
             ]
         }

         collisionShapes: [
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_001.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_002.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_003.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_004.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_005.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_006.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_007.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_008.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_009.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_010.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_011.mesh"
             },
             ConvexMeshShape {
                 meshSource: "meshes/segmentedRing_012.mesh"
             }
         ]
     }

The Mesh Link is a Dynamic Rigid Body with a model and a material. The model loads the mesh from a mesh file. We also have a list of collision shapes that together are combined and form a compound shape for collision detection. Each shape is a Convex Mesh shape which loads the mesh from a source file. A convex shape is basically a shape where the line between any two points within the shape is always inside the shape.

If we take a closer look when the debug mode is enabled, this is how the collision shapes form the compound collision shape:

#### Capsule Link

     DynamicRigidBody {
         property real len: 170
         property real w: 17
         PrincipledMaterial {
             id: material3
             baseColor: "yellow"
             metalness: 1.0
             roughness: 0.5
         }
         Node {
             opacity: 1
             Model {
                 materials: material3
                 source: "#Cylinder"
                 scale: Qt.vector3d(w/100, len/100, w/100)
                 eulerRotation.z: 90
                 y: -len/2
             }
             Model {
                 materials: material3
                 source: "#Cylinder"
                 scale: Qt.vector3d(w/100, len/100, w/100)
                 eulerRotation.z: 90
                 y: len/2
             }
             Model {
                 materials: material3
                 source: "#Cylinder"
                 scale: Qt.vector3d(w/100, len/100, w/100)
                 x: len/2
             }
             Model {
                 materials: material3
                 source: "#Cylinder"
                 scale: Qt.vector3d(w/100, len/100, w/100)
                 x: -len/2
             }
             Model {
                 materials: material3
                 source: "#Sphere"
                 scale: Qt.vector3d(w/100, w/100, w/100)
                 x: -len/2
                 y: -len/2
             }
             Model {
                 materials: material3
                 source: "#Sphere"
                 scale: Qt.vector3d(w/100, w/100, w/100)
                 x: -len/2
                 y: len/2
             }
             Model {
                 materials: material3
                 source: "#Sphere"
                 scale: Qt.vector3d(w/100, w/100, w/100)
                 x: len/2
                 y: -len/2
             }
             Model {
                 materials: material3
                 source: "#Sphere"
                 scale: Qt.vector3d(w/100, w/100, w/100)
                 x: len/2
                 y: len/2
             }
         }
         collisionShapes: [
             CapsuleShape {
                 y: -len/2
                 height: len
                 diameter: w
             },
             CapsuleShape {
                 y: len/2
                 height: len
                 diameter: w
             },
             CapsuleShape {
                 x: -len/2
                 eulerRotation.z: 90
                 height: len
                 diameter: w
             },
             CapsuleShape {
                 x: len/2
                 eulerRotation.z: 90
                 height: len
                 diameter: w
             }
         ]
     }

The Capsule Link is a Dynamic Rigid Body with some models that share the same material. This link is formed from several cylinders and spheres. Like the Mesh Link we have a list of collision shapes. This time each shape is a Capsule Shape.

If we take a closer look when the debug mode is enabled, this is how the collision shapes form the compound collision shape.

Files:

- compoundshapes/CMakeLists.txt
- compoundshapes/CapsuleLink.qml
- compoundshapes/MeshLink.qml
- compoundshapes/compoundshapes.pro
- compoundshapes/main.cpp
- compoundshapes/main.qml
- compoundshapes/qml.qrc
- compoundshapes/resources.qrc