Slider Joint

The Slider Joint allows rigid bodies to rotate around one axis and translate along the same axis.

SliderJoint3D

In Evergine, a Slider Joint is implemented using the SliderJoint3D component.

Common Properties

Property	Default	Description
ConnectedEntityPath	null	The entity path of the connected body. Only when the path is valid is a joint properly established.
Axis	1, 0, 0	The direction of the axis around which the body slides. The direction is defined in local space.
Anchor	0, 0, 0	The position of the axis around which the body slides. The position is defined in local space.
AutoConfigureConnected	true	Enable this setting to automatically calculate the ConnectedAnchor position and ConnectedAxis to match the global position of the anchor property. This is the default setting. Disable it to configure the position of the connected anchor and connected axis manually.
ConnectedAxis	auto-calculated	The joint axis relative to the connected body.
ConnectedAnchor	auto-calculated	Manually configure the connected anchor position in the connected body's local space.
BreakPoint	0	If the value is greater than 0, it indicates the force that needs to be applied for this joint to break.
CollideConnected	false	Determines whether a collision between the two bodies managed by the joint is enabled.

Limit Properties

The following properties set the limits of the rotational movement.

Property	Default	Description
UseLinearLimit	false	If enabled, the position of the sliding object will be restricted within the LowerLinearLimit & UpperLinearLimit values.
LowerLinearLimit	0	The lower distance of the limit.
UpperLinearLimit	0	The upper distance of the limit.
UseAngularLimit	false	If enabled, the angle of the slider will be restricted within the LowerAngularLimit & UpperAngularLimit values.
LowerAngularLimit	0	The lowest angle of the rotation.
UpperAngularLimit	0	The highest angle of the rotation.

Motor Properties

The following properties set the motor properties of the joint.

Property	Default	Description
UseLinearMotor	false	If enabled, the motor makes the object slide linearly.
TargetLinearMotorVelocity	0	The linear speed the object tries to attain.
MaxLinearMotorForce	0	The linear force applied in order to attain the speed.
UseAngularMotor	false	If enabled, the motor makes the object spin.
TargetAngularMotorVelocity	0	The angular speed the object tries to attain.
MaxAngularMotorForce	0	The angular impulse applied in order to attain the speed.

Using Slider Joint

This snippet creates a small bridge of a series of connected bodies.

protected override void CreateScene()
{
    this.Managers.RenderManager.DebugLines = true;

    // Load your material
    var material = this.Managers.AssetSceneManager.Load<Material>(DefaultResourcesIDs.DefaultMaterialID);
    var cubeMaterial = this.Managers.AssetSceneManager.Load<Material>(EvergineContent.CrateMat);

    float sliderLength = 3;

    // Create the slider holder...
    Entity slider = new Entity()
        .AddComponent(new Transform3D()
        {
            Scale = new Vector3(sliderLength, 0.1f, 0.1f),
            Rotation = new Vector3(0, 0, MathHelper.ToRadians(-10)) // Rotate 10º the slider axis
        })
        .AddComponent(new MaterialComponent() { Material = material })
        .AddComponent(new CubeMesh())
        .AddComponent(new MeshRenderer())
        .AddComponent(new RigidBody3D()
        {
            PhysicBodyType = RigidBodyType3D.Kinematic
        });

    // Create the sliding object...
    Entity cube = new Entity()
        .AddComponent(new Transform3D())
        .AddComponent(new MaterialComponent() { Material = cubeMaterial })
        .AddComponent(new CubeMesh() { Size = 0.5f })
        .AddComponent(new MeshRenderer())
        .AddComponent(new RigidBody3D()
        {
            PhysicBodyType = RigidBodyType3D.Dynamic,
        });

    // Create the Joint
    slider.AddComponent(new SliderJoint3D()
    {
        ConnectedEntityPath = cube.EntityPath,
        UseLinearLimit = true, // Limit the slider
        LowerLinearLimit = -sliderLength / 2,
        UpperLinearLimit = sliderLength / 2
    });

    this.Managers.EntityManager.Add(slider);
    this.Managers.EntityManager.Add(cube);
}