Well, the first day of 7DFPS has come and not quite gone, so I figure it’s time for a big ol’ update. It’s been extremely productive as first days go, and so far I think the project is showing a good bit of progress already.
THE DESIGN DOCUMENT
The first item on the agenda was to create a design doc. Shockingly, this was my first time drafting one up, but with no point of reference I think I did quite well. It started as a sort of declaration of purpose, but then went off into outlining the games aesthetics, weapons, enemies, controls, and so on. Some might think writing up a design doc for a game jam game is silly, but I think, especially for a jam as long as 7DFPS, it’s an excellent idea. It gives me something to focus on and work towards, instead of just shooting in the dark to and hoping I hit something worthwhile. I also decided early on that I’d stop adding things to it by tomorrow night, and once that time hits I won’t allow myself to add any new features; it’s a way for me to prevent feature creep. I also decided I can remove items from the doc if I decide it was a bad idea, either due to time constraints or just not being any fun. If you’d like to read through the doc, you can find it here.
So once that was drafted up I started up Unity and began working on what I believed to be the most challenging aspect of the project: the enemy AI. A first-person-shooter with no enemy AI is, art games aside, rather dull. You want something that will instigate and make the player fight back, something that’ll come after them and attack. So I started cracking away at two basic behaviors: wandering around the environment and following the player if it sees them.
The wandering behavior was relatively easy to write up. I created a variable that holds a random point in space, and the enemy slowly turns and moves towards it. While it’s moving towards it’s imaginary target, a countdown timer is ticking away. Once the countdown reaches zero, it picks a new random target and begins moving towards that. There were a couple hiccups here, the big one being for some reason or another the enemy strafed around the object as it moved in, but a quick rewrite fixed it.
Tracking the player was slightly more challenging, but fortunately I’d been playing around with this a bit before. The basic idea is if the player falls within a certain field of view, the enemy would mark it as a target and come after it or attack it. I’m sure there’s a million ways to do this, but my solution was this:
- There’s an empty with a sphere collider on it that’s a child of the enemy. This sphere is the view distance of the enemy, and is set to Trigger mode. When an object sets off the trigger, it’s immediately checked to see if it’s tagged with “Player” or another potential target tag.
- If it is a potential target, it then checks to see if falls within the enemy’s Field of View. This is accomplished by checking the angle of the potential target relative to the transform.forward vector of the enemy. If it the value falls within the assigned field of view, the target is seen by the enemy.
- There is one final check, in which the enemy casts a ray directly in front of itself to see if the target is visible or not. If the target is behind a wall or other obstacle, the first thing to come back from the check will be the obstacle and not the target, and therefore the enemy cannot see the target.
With this check in place, if an enemy sees the player it simply replaces the random imaginary target it was walking towards with the location of the player. If the player walks out of range of the enemy, or runs behind a wall, the enemy walks towards the last point at which it saw the player, and then picks a new imaginary target to walk towards. This gives the player the chance to run away if necessary and hide, and gives the enemy a chance to find the player and continue pursuit.
I did a few other tweaks after this, like finding a new target if the enemy is about to walk into a wall, but this is essentially the whole system. I tried running around a room with about twelve of these guys, and it was surprisingly fun, even in the barebones state it’s in.
WEAPONS AND HEALTH
The next big puzzle piece was how to handle weapons and health. I decided to make the health system an independent component that could be assigned to any object. It has a public variable for assigning it’s health value, and three public functions:
- A damage function, that reduces the health value
- A damagePoint function, that returns the position where the damage occurred (this might change to the point where the weapon was fired)
- A function that returns true if damage has occurred
The damagePoint function is exceptionally nifty, because I can use it to give the enemy a chance to “feel” damage, and react in a semi-realistic way (by turning and attacking in the direction in which it was shot). The damage function, however, is utilized by the Weapon class. Weapons in my game are essentially all the same, much like any other shooter if you stop to think about it. In my project, they boil down to these basic elements:
- Power, or how much damage it does
- Range, or how far it can fire
- Firing Rate, or how frequently the gun discharges while the trigger is held
- Whether it fires a single or multiple shots
- Whether it fires bullets (raycast) or projectiles (instatiated objects, like rockets)
So far the code only handles single-shot weapons (like a pistol or machine gun), but other weapons shouldn’t be too difficult to implement. I’m particularly excited to add rockets for rocket jumping.
Well, I think tomorrow I’m going to complete the weapon code and try to create a few different enemies based on the template I built today. Once that’s in place I’ll work on the item system, which shouldn’t be too difficult (health pickups and weapon modifiers). Finally, I’ll craft up a basic modular level kit and build a stage to test out. After that, if everything works out well from there, it’ll be level design and polished assets the rest of the week! With a bit of work on menus, UI, and all that jazz. Exciting stuff!
If you want to check out any of the stuff I worked on today, hit up my Twitch channel. You’ll find all the day’s recordings there for your viewing pleasure.