[MUSIC] We're all very familiar with virtual characters as we often see them in games or animated films. However, there is a major difference between virtual characters in these two types of media. Which has important implications in terms of how they are designed and implemented. Characters in animated films are often non-interactive, they might be interacting with each other. But we can only passively watch them, either in a cinema or on TV. When we watch them at home, we can choose to play or pause the film. But there is nothing we can do that could change their behavior directly. Characters in games, on the other hand, are often designed to be interactive. That is, they can react to our own actions in real time as we played a game. Generally speaking, there are two kinds of what your characters is games. When we present the player and is often referred to as an avatar or player character PC, the owner is a computer algorithm driven what your character. Often referred to as an agent or non-player character, NPC. For instance in the game, Pac-Man. The character Pac-Man itself is an avatar or PC because it can be directly controlled by the player. The ghosts on the other hand are driven by computer algorithms, and they are called agents or MPCs. You will often have multiple agents in a game. In Pac-Man, there are several ghosts which make the game more interesting as we're chased by several enemies. Some games have multiple avatars as they can be played by multiple users, together. The players of these games can be in the same physical environment. They can be playing the same game sitting next to each other, or they can be together only virtually. For instance, they can be playing a game in their own living room, but unlike the avatars are sharing a virtual space, where they can collaborate or fight with each other. This type of game is often called a massively multiplayer online game, or MMOG. Both agents and avatars could be interactive. In order to achieve this, these virtual characters should be rendered in real time. That is, the graphical representation of the characters are calculated and displayed in real time each frame. As a user, my actions at a current moment could change the character's behavior for the very next frame. In Pac-Man, I can control my Pac-Man avatar using the keyboard to navigate around the environment. The trajectory of its navigation is fully controlled by me. As for the ghosts, although they are controlled by the computer algorithms, their behavior is also influenced by the player. They were programmed to dynamically change their navigation path depending on the player's position and movements. In traditional games, we can control our avatars with game controllers with which we can navigate around the environment, shoot bullets, or select what to do next. In some games, we have a third person perspective. We see the environment from behind a body of our avatar. So we can see where we are going to, as well as the body of our avatar. The other games, we have a first person perspective. So we see the world from the view point of our avatar. For instance in a driving game, we normally have the perspective from the view point of the driver behind the driving wheel. We can only see what's in front of us, so we can't see the full body of our avatar but we might see the hands of our avatar on the driving wheel. In virtual reality, in most of the applications, we should have a first person perspective. So we observe the world from the viewpoint of our avatar. We should also be able to control our avatars using our own body. With the current high end VR systems, our head is tracked with the VR display and our hands with the controllers. In an ideal VR system in the future, we should have more body parts tracked so we can really fully express ourselves in VR through our avatars. This will allow us to use our body to interact with objects and navigate in the virtual world and engage in social interactions with other agents or avatars just like we do in real life. [MUSIC]
