V2020.1.56.3_ Prismatic Joint



Overview

Constraints the motion of a GameObject to a translation over a Spline.


Where to find

The Prismatic Joint can be found under Mechanics > Add Kinematics > Prismatic Joint and will be added to the selected object. Without a selection a Prismatic Joint will be added to a new Empty GameObject.

Joints must be placed as children of a Kinematics Controller in the hierarchy

The inspector component looks as below:


Feature layout

The image below shows the complete feature layout of the Prismatic Joint component.

Generic Joint Settings

 

Pass Priority

Priority of the kinematic chain calculations. Higher numbers are calculated earlier

Enforce Outside Playmode

Enforces the prismatic joint in edit mode

Prevent Kinematic Update

Removes the prismatic joint from the kinematic chain calculations

Prevent Further Kinematic Update on this GameObject

Allows lower priority kinematic transforms on the same GameObject to be skipped in calculations

Allow Direct User Input

Allows the user to manipulate the prismatic joint with the scene gizmo

Min. User Input Translation Offset

The minimum value the user must input before translations are applied

Min. User Input Rotation Offset

The minimum value the user must input before rotations are applied

Kinematic Chaining

 

Opposing Relation Instance

The kinematic transform to which you want to link the prismatic joint to

Relation Direction

Describes the direction of the manipulation of the Transforms. The following options are available:

  • BIDIRECTIONAL: Allows for both kinematic transforms, when they are being manipulated, to manipulate each other equally

  • RECIEVE_ONLY: Allows for the prismatic joint, when it is being manipulated, to manipulate the opposing kinematic transform, but not the other way around

  • SEND_ONLY: Allows for the opposing kinematic transform, when it is being manipulated, to manipulate the prismatic joint, but not the other way around

Relation Type

Not yet implemented

Motion Direction is Reversed

When enabled, the manipulation to/from the opposing kinematic transform is inverted

Limit Relation & Update Settings

 

Spline Input field

Defines the spline to which the Prismatic Joint is bound to

Prismatic Joint Settings

 

Spline Constraint Lenght

The length of the spline

Current Spline Position

Normalized position of the Prismatic joint over the spline between 0 and 1

Target Control Point

The Spline point to be used for Update Limit ControlPoint

Update Limit ControlPoint

Updates the Target Control Point to the current spline position


How to use

1. Create a Spline and use it to define the path you want the prismatic joint to follow

2. Add the Spline to the Prismatic Joint and create a new Transform Relation, add an Opposing Relation Instance and define the other settings as required

3. Test if the Transform Relations are working

To test your Transform Relations outside of playmode make sure Enforce Outside Playmode is checked on both Joints


How to use Limits

1. Position the Prismatic Joint object along the spline

2. Select the point in Target Control Point you wish to change and click Update Limit Control Point