Add basic background music behavior

Assets/Scripts/GameSystems/BGMusic.cs

@@ -0,0 +1,60 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+//Define the background music behavior.
+public class BGMusic : MonoBehaviour
+{
+    public int intensity =0; //Current intensity level
+    int intensityLevels = 2; //Number of intensity levels (differents tracks)
+    [SerializeField]
+    AudioClip AudioIntensity0, AudioIntensity1; //Must have enough clip foreach intensity levels
+
+    List<AudioSource> audioSources; //Sources used for each intensity clips
+
+    //Change the intensity level of the music
+    //TODO: Smooth transition
+    public void changeIntensity(int level)
+    {
+        if(level>=intensityLevels)
+        {
+            Debug.LogWarning(gameObject.name+" doesn't have such high intensity available :"+ level+ " /"+intensityLevels);
+            level = intensityLevels-1; //Max level
+        }
+            
+        for(int i=0; i<intensityLevels; i++)
+        {
+            if(i!=level)
+                audioSources[i].volume=0.0f;
+            else
+                audioSources[i].volume=1.0f;
+        }
+
+        intensity = level;
+    }
+
+    // Start is called before the first frame update
+    void Start()
+    {
+        audioSources = new List<AudioSource>(GetComponents<AudioSource>());
+        if(audioSources.Count != intensityLevels )
+            Debug.LogWarning(gameObject.name+" missing audio sources too play all intensity levels : "+ intensityLevels);
+
+        //Load clip
+        audioSources[0].clip = AudioIntensity0;
+        audioSources[1].clip = AudioIntensity1;
+
+        //Set initial intensity
+        changeIntensity(intensity);
+        
+        //Start sources
+        foreach(AudioSource s in audioSources)
+            s.Play();
+    }
+
+    // Update is called once per frame
+    void Update()
+    {
+        
+    }
+}