Joints. If you look around, you will see that joints play a huge role in the physical world. For instance, take a look at furniture or doors. Joints attach a body to another and depending on the type of joint, movement is restricted. Even in the human body, there are 360 joints. So of course unity added the concept and tools to simulate joints in the game. This Tech-Recipe will briefly cover how to use joints in Unity.
In unity, you can use the joints to attach a rigidbody to another. According to the requirement, you can restrict or allow movement. Joints also have other options that can be enabled for specific effects. For example, you can set a joint to break when the force applied to it exceeds a certain threshold. Some joints also allow a driving force to occur between the connected objects to set them in motion automatically.
For example, if you want to simulate a pendulum you can child your pendulum object to an empty gameobject. Then move the child down so that the empty object is the “pivot”.Then you can use the rotating code on the parent.
This Tech-Recipe will introduce you to all the joints that can be used in unity with examples.
How to Use Joints in Unity
There are five types of joints in Unity. Let’s discuss each.
1. Character Joint
You can also call this joint a ball and socket joint. It is so named due to the similarity with a human joint. Character Joints are mainly used for Ragdoll effects. They are an extended ball-socket joint which allows you to limit the joint on each axis.
2. Configurable Joint
Skeletal joints are emulatable using configurable joints. You can configure this joint to force and restrict rigid body movement in any degree of freedom. This joint is more flexible and is the most configurable joint. It incorporates all the functionality of the other joint types and provides greater control of character movement. 
3. Fixed Joint
This joint restricts the movement of a rigid body to follow the movement of the rigid body it is attached to. In unity, you can relate two bodies to transform by parenting one to the other. But this joint can be used to do the same. Also this joint is used when you want two connected bodies apart.
4. Hinge Joint
This joint simulate pendulum like movement. It attaches to a point and rotates around that point considering it the axis of rotation.
5. Spring Joint
A slinky can be simulated using this joint. Keeps rigid bodies apart from each other but lets the distance between them stretch slightly.
There are other joints too, slider, target, spring, relative and friction joint. But we will discuss those in other Tech-recipes
We will discuss each joint in the next Tech-Recipes.
Unity Tech-Recipes
How to Set Camera to Follow the Player in Unity | 3D Game Development
How to Add Rigidbody to a Gameobject in Unity | 3D Game Development
Detect Collision in Unity | 3D Game Development
How Can I run Unity 3d in Windows 7 64-bit?
How to Perform Simple Animation in Unity | 3D Game Development
