Increase volume when key is down and decrease volume when key is up

Questions & Answers
1

So i’m trying to make a very simple car engine where I press the ‘W’ key and the engine sound gradually increases and when I leave go of the ‘W’ key the volume gradually decreases. I can’t seem to get it to work.

using UnityEngine;
using System.Collections;

public class CarEngine : MonoBehaviour {

    float IncVolume = 0.6f;
    float DecVolume = 0.6f;
    float VolumeRate = 0.1f;

	void Update () {

        if (Input.GetKeyDown(KeyCode.W))
        {
            IncVolume = IncVolume + (VolumeRate * Time.deltaTime);
            GetComponent<AudioSource>().enabled = !GetComponent<AudioSource>().enabled;
            GetComponent<AudioSource>().volume = IncVolume;
        }

        if (Input.GetKeyUp(KeyCode.W))
        {
            DecVolume = DecVolume - (VolumeRate * Time.deltaTime);
            GetComponent<AudioSource>().volume = DecVolume;
            GetComponent<AudioSource>().enabled = !GetComponent<AudioSource>().enabled;
        }
	}
}

I have the IncVolume and DecVolume at 0.6 because that is the volume thats in the Inspecter and I want to increase and decrease the volume by 0.1 every second or so.

2

Functions GetKeyDown and GetKeyUp works, when user starts pressing down or up the key, one time. I correct your code:

private int grad = 0; // add one more variable for graduation volume effect

void Update () {
 if (Input.GetKeyDown(KeyCode.W)) {
  grad = 1;
 }
 if (Input.GetKeyUp(KeyCode.W)) {
  grad = -1;
 }
 if (grad != 0) {
  this.audio.enabled = true;
  this.audio. volume += grad * VolumeRate * Time.deltaTime;
  if (this.audio.volume < 0.1 || this.audio.volume > 0.6) {
   if (this.audio.volume < 0.1) {
    this.audio.volume = 0.1f;
   } else {
    this.audio.volume = 0.6f;
   }
   grad = 0;
  }
 }
}