In game development, the creation of animation falls under the responsibility of an animator. Before an animation can be first created, we need to first have a 3D model that's been created by a 3D modeler. The 3D modeler is responsible for giving the object its shape and texturing it. Depending on the type of object we're dealing with, the exact process to get an object properly rigged can be slightly different. Rigging needs to be done before handing over the object to the animator to create specific animations. Sometimes, animators also need to fine-tune the rigs for better control of the animation.

Rigging is a process where a skeleton is placed in the mesh and joints that are created for the skeleton. The collection of bones/joints is known as the rig. The rig provides control points, which the animator can use to move the object in order to create the desired animation. I will use a human character model in my explanation here so that you can understand this concept easily.

The 3D or character modeler first shows how the face and body of a model are shaped. It then determines how tall the model is, creates all the required features by adding primitives to the model, and then textures it to give color to its eyes, hair, and so on. The model is now ready but still jelly on the inside because we have not given it any internal structure. Rigging is the process where we add bones to the body to hold it up. The arm can be rotated because we have given it a shoulder bone (scapula), arm bone (humerus), and a joint that can mimic the ball and socket joint. The joint we have in place for rigging is made up of a group of constraints that limit movement in various planes and angles. Hierarchies are also applied to the bone structure to help the bones link each other. The fingers are linked to the hand, which is linked to the arm. Such a relationship can be put in place so that movement looks real when one of parts moves and the rest of the parts naturally move together as well.

Tools, such as Maya and 3ds Max, provide some simplification to the rigging process, as you can use standard rigs as the base, and tweak this base according to the needs of the model. Some models are taller and require longer bones. A 3D model must have a simple skeletal structure that adheres closely to the shape and size of a 3D model. Similar sized 3D models can share the same skeletal structure.

To better understand how we can add animation to our game levels, let's learn how computer animation is created and how we can make these models move.

Animation basically mimics how life moves in the real world. Many companies go to great lengths to make computer animation as accurate as possible through the use of motion capture. They film actual movements in real life and then recreate these movements using computer 3D models.

When creating animations, the animator makes use of the bones and joints created during the rigging process and adjusts them in place using as much detail as possible to mimic their natural movement. The joints and bones work together to affect the body posture. These movements are then recorded as short animation clips known as an animation sequence. Animation sequences form the most basic blocks of animation, and they can be played once or repeatedly to create an action. For example, a walking animation is only 1.8 seconds long but can be replayed over and over to simulate walking. When this sequence is repeated again, it is commonly known as an animation loop.

Animation sequences can also be linked to form a chain of actions. While transitioning from one sequence to another, some blending might be needed in order for the movement to look natural.