FPS Reference

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Contents

Overview

Advanced Customizable Character Controller

A key feature of any FPS is how the character moves around in the world. The default Heroengine ACCC is setup well for a mmorpg character but not for a FPS character. The first step to that goal was that a new character model and animation set were developed. Then we overrode certain server scripts to make sure characters start with a FPS character controller rather than the default one.

The character controller then needed to turn inputs from the user in to specific animations and behaviors for the new character model. The basic ACCC was gutted of most of its features to be more streamlined with our needs. In some cases this just meant deleting large sections of code that just were not relevant to FPS,for example swimming logic was taken out. There is no water in our game design so there is no need for the character controller to know how to swim. In other cases code need to be added for new behaviors. One of the things that needed to be added was a tracking of which limbs you are missing. The major hook of our game was that missing limbs would result in your character controlling differently so the ACCC needed to be keep track of which ones you had or did not.

Another major concept that the character controller needed to handle was the fact that character rotation would no longer be dictated by the direction the character was moving. In the HeroEngine default controller depending on where your camera is facing your character willw animate and turn toward that direction. In a FPS movement almost never controls where you are directly aiming. This took handling of the character rotation out of the controllers hands.

In most cases you do not want the ACCC to be involved in game logic. The ACCC should sit between your game logic and animating the character. This means that the ACCC should react to commands from your game logic and interpret all the different signals its getting in to one final action. There are cases of where the FPS ACCC does not do this. While it technically works it means that there is tight coupling between different game systems and the character controller.

Scripts Involved:

Server - Client Communication

Weapons and Attacking

AI

Stat System

Modern FPS games track stats for many different actions. Those things can range from bullets fired, accuracy, steps taken, head shots, and the list goes on. In this implementation for simplicity stats are not persisted and we only track kills and deaths. We centralized stat tracking in to a system node that would get updates on the server for players various actions. The stats system could be easily extended to include more stats via the observer/listener pattern and adding in more fields.

The way it works right now is when a player joins the match they also register themselves with the stats system. Once registered their account ID is added in to a lookuplist on a statnode on the server. The stat node is tracked by the stats system and replicated to all clients registered with the stat system. When updates to the node happen the stat system is notified and then sends out messages to any systems that care about the update. Most notably the leaderboard on the client tracks stats and displays the proper information in real time.

The main drawback with the current implementation of the stat system is that it is not persisted. Stats are tracked for the duration of a player being in a match and then discarded if the player leaves the game ever. To implement a system that will permanently keep stats the server would need to write out files to the repository or make a arbitrary root stat node that is associated to the account root node. Since a system like that was beyond the scope of our demo we did not go with that implementation and kept it simple.

Scripts Involved:

Camera

The camera in any FPS needs to feel smooth and responsive to allow for good accuracy. The rotating of the camera was kept very basic. As the player moves the mouse the camera is rotated based on user's mouse sensitivity settings. This does make the camera feel very responsive, but it does mean that small corrections in aim can be hard to do. Some form of mouse acceleration would need to be used to combat lower DPI mouses and inaccuracies with mouse movement.

New command layers were added in to the gamekeybindings.ini file in the repository to handle mouse movement. This allowed us to turn on and off mouse camera control as needed. Also the external functions GetIgnoreCursor() and SetIgnoreCursor( ignore as Boolean ) Allowed us to lock the mouse to the center of the screen. With out using that external function another method of moving and locking the cursor would have been needed. In most cases SetIgnoreCursor will be what you want to use to keep the mouse in the viewport for a fps.

Lastly we added in a death cam for when a player dies. This leverages the external functions involving a camera to provide a cinematic feel. Again we kept it simple just to show how a death camera could be done. In its current implementation the death camera will position its self exactly where the FPS camera is. Once it is position the camera will pan down and move up to show the player their exploding robot. If a death cam was not put in the player's view would be be locked in to the same position as the robot producing a weird view.

Art

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