Tower Defense Tutorial Fixing Scene Manager

digm520admin / / Programming, SceneManagement, Unity

Tower Defense Tutorial Fixing Scene Manager

June 19, 2019

Tower Defense Tutorial Project

Fixing Problems with the Scene Manager

To help get back into the groove of working on my tower defense project, I went over some scripts that I thought might help fix problems and listed out how they reference each other. (Lower placed scripts reference the higher ones)

Script Reference List

  • PlayerStats
    • LevelPlayerStats
  • WaveSpawner
    • WaveInformation
    • LevelManager

Then I got working on the problems with the scene manager and the method call timings between the different scenes that were giving me errors. There are a lot of issues when references trying to be called before variables are properly set in different scenes, and this offset is leading to a lot of errors where the checks are checking against default values like 0 and null as opposed to their properly set values. So once again, I made a list of problems as I encountered then and possible fixes I tried, including the ones that finally worked and stuck for now.

SCENE PROBLEMS

Problem

Menu buttons do not work

  • Going back to the level select menu screen is not working on either button, so Menu() method must be incorrect
  • The for loop to deactivate level buttons the player should not have reached yet was given the wrong value to start with when reactivating the scene
    • it was setting a value to the active scene’s index and adding that to the for loop check for the level select button array
    • this value was initializing at 0 the first time through for some reason (another scene timing error), but was then being set to 4 when returning (which I believe is the level scene’s index, so this is another scene timing issue, but being properly set to 3 [the index of the level selection scene] would have been bad as well)
Solutions
  • Solution: Just removed the addition of the current active scene build index all together; I think this was added at some point to process the correct level build indices, but that is no longer needed.



Problem

Retry for a level does not work

  • Clicking retry does unload and reload the current level scenes, but it is done so improperly and the timer does not count do to start the first wave ever
  • Just ever unloading a level scene and trying to load it again has the same problems
    • This indicates something is not being properly reset the second (or more) time the scene is loaded
    • Look to individual Level scene and Base scene (created for all levels), especially in Start type methods
    • EnemiesAlive and WaveIndex are not resetting to 0 when scene is unloaded
      • EnemiesAlive specifically is one of the checks to see if a wave should be spawned (spawns a wave when the value is at 0 to make sure the previous wave was defeated)
Solutions
  • Potential Solution: reset these values to 0 when level scenes are loaded
    • tried this by creating a ResetWaveSpawner method in the WaveSpawner itself, then having something reference this on Start with something that is created on Level load
    • started method in Start method of LevelManager script
      • this actually worked for going back to the menu and then trying the level again, but retry still did not work properly
      • I figured this meant the scenes might be loaded/unloaded differently, so I checked my sceneManagerLite and sure enough, the level selection from the menu needed to load both the Base and Level scene, but retry was JUST unloading/reloading the Leve scene, not the Base scene, which is where the LevelManager is located that is resetting the wave spawner on Start
  • Potential Solution: just have the reset called in the Start method of something in the Level scene itself
    • This did allow the level to start properly when returning to the menu and coming back, or with the simple retry. However, there were still some other problems. Now if you beat a level, every time you returned the game won screen would come up and the game would still play in the background. Leaving the level during play and coming back (by menu or retry) would also change the “Rounds Survived” counter at the end, indicating something with the wave counters was not resetting properly.



Problem

Beating Level Once Beats it Forever

  • After beating level, game won screen comes up immediately when going back to the level
  • Back to our game winning bool checks, appears that the WavesFinished bool is not properly reset when returning to a level. This should be false every time the player starts the level, and get set to true when they win. This is happening correctly, but it is never reset to false.
Solutions
  • Possible Solution: reset the WavesFinished bool in WaveSpawner with proper scene timing
    • Actually just added this to the newly created ResetWaveSpawner method I created to deal with the previous resetting issues and this fixed it



Problem

Wave Spawning Coroutine is Off

  • Resetting a level during the spawning of a wave has the rest of the wave spawn immediately (at the beginning of the newly reset level) as well as spawning the second wave (skips the spawn of the first wave all together)
  • This indicates the coroutine spawning the wave might need manually jumped out of on reset and that the wave index is being messed up by their being enemies remaining