音频源的音量（0.0 到 1.0）。
AudioSource 的音量属性控制来自 AudioClip 的声音级别。最高音量等级为 1，最低音量为 0（此时听不到声音）。
using UnityEngine;
public class Example : MonoBehaviour
{
AudioSource m_MyAudioSource;
//Value from the slider, and it converts to volume level
float m_MySliderValue;
void Start()
{
//Initiate the Slider value to half way
m_MySliderValue = 0.5f;
//Fetch the AudioSource from the GameObject
m_MyAudioSource = GetComponent<AudioSource>();
//Play the AudioClip attached to the AudioSource on startup
m_MyAudioSource.Play();
}
void OnGUI()
{
//Create a horizontal Slider that controls volume levels. Its highest value is 1 and lowest is 0
m_MySliderValue = GUI.HorizontalSlider(new Rect(25, 25, 200, 60), m_MySliderValue, 0.0F, 1.0F);
//Makes the volume of the Audio match the Slider value
m_MyAudioSource.volume = m_MySliderValue;
}
}