Author: digm520admin

March 8, 2019

Tower Defense Tutorial

Episode 28 – Winning Levels

Youtube – How to make a Tower Defense Game (E28 WINNING LEVELS) – Unity Tutorial

By: Brackeys

Ep. 28

This tutorial sets up the system for what happens when the player beats a level.

We began by creating a UI panel for all of the UI that should appear when the player completes a level.

Once we had that setup, we looked into creating some functionality for this screen. This started by creating a RoundsSurvived script to just place on any round counting objects (one in the game over and level won screen) to display the text properly. As an added effect, we wanted to animate the round counter to count up from 0 to give it more of an impact than simply displaying the number.

To get this round counter animation effect, we used an IEnumerator for its ability to WaitForSeconds. We created a while loop that would count from 0 to the number of rounds the player survived one at a time, with a WaitForSeconds of 0.05 each time. This provides the rapid counting effect we’re looking for to spice up the round counter.

The tutorial goes over a bug where enemies could die multiple times because of the fact that Destroy(gameObject) is not a very immediate process within Unity. Since our enemy script just checked if health reached 0 or less to determine if an enemy would call the Die method, which would then destroy it, sometimes this would allow it to call the Die method multiple times if it got shot repeatedly in a small time frame. To solve this, we just added a bool isDead, and have the check to call the Die method see if health is at/below 0 AND !isDead to ensure this is only called once (the Die method sets isDead to true).

PROBLEMS

As indicated in the comments for the tutorial video, there is an issue when selecting the Menu button upon completing a level. The Continue method is where the levelReached Player Pref is updated, so if the player simply selects the Menu button instead, the levelReached is never updated so the player will not be able to select the next level in the level selector.

SOLUTIONS

To keep the levelReached and levelToUnlock variable in the CompleteLevel script (as opposed to the Game Manager) and fix this issue in as clean a way as possible, the comment suggested moving these variable updates to an OnEnable method. This is nicer than just adding it to both methods, and keeps it within the same script which is helpful if I intend on making the GameManager into a prefab in the future.

SUMMARY

• Rule of Thumb: “Bigger” highlight animations for bigger buttons
• In Unity, if you want your button to be just text, you can also drag the Text element of it into the Target Graphic of the Button (script) so the text is the specifically clickable area
• IEnumerators are used when you want a method that can be paused to continue at a later time (can be as small as a frame or two)
• Destroy(gameObject) in Unity is SLOW. This is always a good piece of code to look around if you are having strange bugs/issues.

March 7, 2019

Tower Defense Tutorial

Episode 27 – Unlock Levels

Youtube – How to make a Tower Defense Game (E27 UNLOCK LEVELS) – Unity Tutorial

By: Brackeys

Ep. 27

This tutorial gets into creating a system for locking/unlocking levels.

We started by going into our LevelSelector script and creating an array of UI Buttons. This would hold all of the buttons that allow you to select a specific level on the level select screen. We then added a for loop to go through all of these buttons and intitialize them as non-interactible buttons.

To go along with making the buttons non-interactible, we added a Button Disable animation. This was a simple animation that makes the button much more faded out than normal to make it clear that it is non-interactible. To make sure this effect is removed in an interactable state, we added an alpha animation for every other button animation state to just set the alpha back to 1.

Next we needed a way to keep track of the player’s progress to determine what levels they have access to. We wanted this to persist even if the player closes the game, so static variables are not enough. To do this, we need to save data out to a file. We used Unity’s player prefs as the simplest way to do this. We started by creating an int levelReached, which uses PlayerPrefs to GetInt levelReached. When using a get variable command, you also specific a default value to use if there is nothing associated with this value currently (i.e. this is the first time the player is playing the game), so we set that to one so the player will always have access to level 1 initially.

Now we setup that initial for loop that was just disabling every button to only disable buttons if their index (+1) is greater than the levelReached variable. The levelReached variable is now set at the end of a level if the player completes it, increasing the possible level options.

In testing the level select setup, they discovered the bug I mentioned as a possible issue in a previous tutorial. You can sometimes get a scenario where the enemiesAlive in the middle of a wave reaches 0, which signals to our system that the wave is over, even though there are actually more enemies left in the wave. They ended up using my suggested solution as well: just set the enemiesAlive variable equal to the total number of enemies in the wave at the very start of the wave.

They then go over some issues with modifying the game in its current setup. The changes we made in the Game Manager only apply to the current scene, so they have to be redone in every other level (or since we don’t have anything yet, delete the current ones and duplicate the updated level scene). The simple work around for this was to make objects like the GameManager a prefab so when you update it in one scene, it will be updated for every scene. Then, for an even stronger method they suggest is that Unity allows you to put everything that is repeated in each level into its own scene, and only the objects that actually change between levels are their own scene.

SUMMARY

• Look into serialization for saving player data; many more advanced games use .json or .xml to store player date
• Unity uses Player Prefs to do a very simple version of saving data
• When using get/set variables, make sure to use the EXACT SAME identifier name for the variable. This will not generally return an error if entered incorrectly as it will just set it to the default value instead.
• Unity has a system to let you load different scenes in at once, look into properly using this feature (this was the suggested ideal method if you want to create a lot of levels)

March 6, 2019

Tower Defense Tutorial

Episode 26 – Fading

Youtube – How to make a Tower Defense Game (E26 LEVEL SELECT) – Unity Tutorial

By: Brackeys

Ep. 26

This tutorial gets into creating a level select menu for the player.

This would require its own scene, so we duplicated the Main Menu scene as a place to start since it’s already fairly empty. We started by setting up the hierarchy of UI assets for the level content selection area. It was noted that this is a general way to setup a scrolling menu for selecting objects in Unity.

The hierarchy is as follows:

• UICanvas
• Title
• Levels
  • ScrollRect
    • Content

We then added a button to our Content UI object, and gave that object a Grid Layout component. This allows Unity to place everything in an even grid layout for you. We also added a Content Size Fitter. This helps allow the object it is attached to scale to fit the content placed in it. We also made sure to move the pivot anchor point of this UI object to the top of the object to make sure it scales downward from that point instead of out from the center.

We added a bunch of buttons to help see that all of the scaling and clipping was working properly with the UI elements. To help keep them from flowing out of the menu (which also works with the idea of creating a scrolling menu), we added a Rect Mask 2D component to the ScrollRect object which blocked out child objects that were not within this rectangle space.

Speaking of scrolling, we added the Scroll Rect component to the ScrollRect object next. This just required dragging in the ScrollRect object as the viewport and the Content object as the content to start this working. This did have a slight issue for me where it seemed that I could only scroll if I clicked/held on a button in the content area. If I clicked/held on an empty space within the content area, I could not scroll the menu, so that would have to be fixed.

We created a simple LevelSelector script and placed it in an empty gameobject. This script provides the method for the onclick event for each of the buttons to reference to take the player to the corresponding level. To help test this, we just duplicated our initial level and changed the number of lives to create a level 2.

Finally, we added a scrollbar component to the Levels object to go along with the scrolling of our scroll rect. It just gives another, clearer option for scrolling, especially for someone using a computer.

SUMMARY

• Check pivot/anchor point locations for scaling UI elements, especially those using a component like Content Size Fitter.
• Implementing scrolling into UI elements in Unity is straightforward with ScrollRect and Scrollbar components.