Full LibGDX Game Tutorial – Game Mechanics

Sharing is caring!

Full LibGDX Game Tutorial – Game Mechanics

Welcome to part 12 of our Full LibGDX Game Tutorial. This part will focus on adding some game mechanics such as springs for jumping higher, a scoring system and DEATH. If you haven’t seen the earlier parts of this tutorial I advise you to start at Full LibGDX Game Tutorial – Project setup as this tutorial continues from these earlier parts. For those of you who have come from part 11, you can continue on.

In the last part of this tutorial we added the simplex noise generator to our game and then used it with a level generator to create levels. In this part we will start with adding a Utils class which I stole from one of my other games which has some static methods in when can be reused in other games. We will also add a mechanic to generate bouncy springs on some of our randomly generated platforms and finally and a score and death mechanic.

Game Mechanics – Adding a utility class

Firstly lets add the Utils class so we can access then in our project.

The Utils class has some useful methods such as converting HSV colour values to RGB and Creating textures at runtime. We will be using the ones that generate textures at runtime so we can create placeholders for our entity images instead of having to create nice textures. (mostly because I suck at drawing)

Game Mechanics – Adding Springs

Now we have our Utils class lets get on with the game mechanics. We want to add some springs to some of our platforms so we will update our levelFactory’s generateLevel() method so it will use an extra 2 noise values to check if a platform should have a spring on it.

Here I have added noise5 and noise 6 to be the deciding factor for springs on platforms. I have also added noise 7 and 8 for future use. In the if conditionals I have added another if conditional for noise 5 and noise 6 and if the values fall in range we createBouncyPlatform(). Lets create that method now.

This method simply adds a small cube in the middle of the platform, sets it to a sensor so it doesn’t block the players movement and sets its type to SPRING. This type setting is important as we check for this value in our collisionSystem already, and now all we need to do to react to the touching of springs is check for it in our collisionSystem and update the player.

Our collisionSystem needs to be updated to:

In the collisionSystem we check if the player has hit a spring and if they have, we set the player onSpring to true. The last thing to do to get the player to jump from a spring is to actually make the player jump. This is done in the playerControlSystem with a simple if conditional.

Here we have added a force to the player to make the go upwards and set their state to jumping so the player can’t jump again. We then reset the onSpring flag so the player isn’t continuously getting shot upwards.

Game Mechanics – Increasing Water and DEATH.

Now let’s add the death mechanic. The player will die instantly the moment they are touched by the water coming from the bottom of the world. To do that we first need to add the water and the first part of that is to make the waterFloorComponent.

This component is simply here to identify the water. The next thing we need to do is to make a system that moves this water upwards at an ever increasing speed and that system is this:

We also need to add this to our engine like all other systems in our MainScreen class:

Here we have added the WaterFloorSystem and added the player as an argument. This is because we want to increase the speed of the water the higher the player gets so the game becomes more difficult the higher you get.

The waterFloorSystem can now control the increasing water but we haven’t created the water yet. We need to ad a method to our LevelFactory that creates and entity that can be moved and that method is:

Things to note about this is that we make the waterFloor a KinematicBody. This is a box2d body type that says this block will be moved using code and should not be effected by gravity. We also set the type to ENEMY so that if our player hits this they will be killed.

All that’s left to do is to add a call to this method to create the water floor and we will do that the same place we create the normal floor in our MainScreen method. Update your MainScreen code to this:

Here you can see we started using the DFUtils class to make some images using some HEX values instead of creating images and loading them in. You will also notice we use the PPM constant form the RenderingSystem. You will have to make this field public in the RenderingSystem class so we can access it in the above code.

Currently all that happens here is that when the player hits the water it writes “player hit enemy” and we want it to actually make the player dead. To do that we need to add a field in the player component. A simple boolean isDead = false will do. Once you have added that we can updated our CollisionSystem to flip this to true if the player hits an enemy with this code:

In this code we have flipped the isDead flag for the player so they become dead and as a bonus we also added some code to print out the score which is derived from the height the player got to before they died.

Once you are finished you should end up with something similar to this when you start your application:

As usual the complete code up to this part is available from StorMyVids. The next part, Part 13 will go over the enemy system and how to add them to our game.

If you find mistakes with this article or have some improvements please leave a comment below

← Simplex Noise and Level Gen

— Contents —

Ashley Enemy System →

 

Sharing is caring!