Week 3: Core Mechanics & Research

This weeks development consisted of making initial prototypes of the core mechanics. Things like interactables, buyable objects, and perks. I also added some more logic to the health system. I changed the way the player switched between guns as well as how the player inventory works to allow buying and switching guns. In my last post, I mentioned that I would have started some level blackouts however I have moved that to the start of week 4. Along with the project development I have spent some time looking into my research topics.

So my first task of the week was to set up a modular purchase system. My goal for this was to create a system that would allow the player to buy things within the level. This could be things like guns and perks. I started by creating a new blueprint component that would handle the purchasing. For the currency in the game, I added a points variable to the player. This allows me to add points to that variable based on killing zombies. Within the purchase component, I added a purchase cost variable that can be changed on a per-actor basis to allow for different objects to have different purchase costs. I then added a function that will get the points variable from the player and subtract the purchase cost as long as the player has enough to cover the cost. With this function set up, I could then set up logic that could be run after making a purchase.

Even though the player can purchase things with the points they acquire, they have no way of spending them as the player can't physically interact with anything yet. With this in mind, I set up some interact events to allow the player to press a button which will then interact with the desired actor. I began with setting up a new blueprint interface that will handle the interact events. I created a new key bind using Unreals enhanced input system.

I wanted to have 2 different ways for the player to interact with items. The first method is that the player is simply in range of the object to interact with it and the second method is that the player will need to look at the object when interacting with it for it to trigger. I started with the first method.

As long as the player is overlapping the object when the interact input is triggered, it will then send a message to the actor that has been interacted with. This will then run the event and whatever logic is attached to that event. This means that I just need to add the interface to any actor with a single button click and it will be able to be interacted with.

The next method uses a line trace from the camera position, to detect what actor has been hit. This makes the player need to look at the object they want to interact with as the line trace will, In the same way, check if the hit actor implements the interface and will then send the interact message to the hit actor.

So because each input uses a different interface message I can use different events for different actors to change the interact method.

My next task was to update the weapon-switching logic. I needed a way for the player to hold 2 different guns at a time and be able to switch between them. I also needed a way to change those guns to allow the player to buy new ones.

I updated the weapon switching to prevent the player from being able to switch to the gun they already have in their hands. This means that the switching will only play when it recognizes a different gun to be switched to. I added some ID variables to the player to handle the weapon slots. This helped when creating buyable weapons to put weapons into the correct slot. I did it his way to avoid making changes to the dynamic inventory where all of the dynamic stats for the guns are stored otherwise the order of guns will start to break.

For the buyable weapons, I started with implementing the interface so the player can interact with it and then added the purchase function so that the game will check if the player can buy it. At this stage, I also added an output to the purchase function to send out a success or failure for the purchase. This will then end the logic if the purchase is not successful (not enough points to complete the purchase). If the purchase is successful then it will get the current GunID from the player, which is the gun slot. and then update the gun in that slot. The event will also check if the player is already holding that specific gun in either slot to prevent holding 2 of the same gun. This can be further expanded by adding additional purchase options based on whether the player already has the gun equipped.

With this system set up, I can simply create multiple different 'gun buy' actors which can placed around the level to allow the player to obtain different guns. I just need to change the mesh inside the actor and then change the gun ID to change the player's gun for their current slot. I can also use this logic for buying other things in the game. I set up the first perk with some basic logic. When the perk is purchased it will increase the maximum health of the player character.

As shown in last week's update, the zombies can attack the player. I have updated the health system to reflect being hit by the zombie. Also after a brief delay of not being hit the player's health will recharge back to full health. I have also added an on-death state so if the player hits 0 health, they will die. Each time the player is hit, it will have a UI blood effect show up on the screen. I have turned down the opacity of the effects until the player is one hit away from death at which point the screen will go full red to signify the player is almost dead. I created the splatter effect in Photoshop with some basic shapes and a splatter brush. I then put the image inside the player HUD widget and set it to hidden from the start.

This covered the main aspects of the development for this week. The rest of my time this week was spent outside of Unreal, watching GDC talks and reading sections of the game feel book. I've also highlighted some more traditional rogue lite games that I will research for additional topics. My goals for next week are to further elaborate on the mechanics created this week. I will also start the block-out process for the level and adding in the current mechanics that are set up.