using System;
using UnityEngine;
using Random = UnityEngine.Random;
namespace UnityStandardAssets.Vehicles.Car
{
[RequireComponent(typeof (CarController))]
public class CarAudio : MonoBehaviour
{
// This script reads some of the car's current properties and plays sounds accordingly.
// The engine sound can be a simple single clip which is looped and pitched, or it
// can be a crossfaded blend of four clips which represent the timbre of the engine
// at different RPM and Throttle state.
// the engine clips should all be a steady pitch, not rising or falling.
// when using four channel engine crossfading, the four clips should be:
// lowAccelClip : The engine at low revs, with throttle open (i.e. begining acceleration at very low speed)
// highAccelClip : Thenengine at high revs, with throttle open (i.e. accelerating, but almost at max speed)
// lowDecelClip : The engine at low revs, with throttle at minimum (i.e. idling or engine-braking at very low speed)
// highDecelClip : Thenengine at high revs, with throttle at minimum (i.e. engine-braking at very high speed)
// For proper crossfading, the clips pitches should all match, with an octave offset between low and high.
public enum EngineAudioOptions // Options for the engine audio
{
Simple, // Simple style audio
FourChannel // four Channel audio
}
public EngineAudioOptions engineSoundStyle = EngineAudioOptions.FourChannel;// Set the default audio options to be four channel
public AudioClip lowAccelClip; // Audio clip for low acceleration
public AudioClip lowDecelClip; // Audio clip for low deceleration
public AudioClip highAccelClip; // Audio clip for high acceleration
public AudioClip highDecelClip; // Audio clip for high deceleration
public float pitchMultiplier = 1f; // Used for altering the pitch of audio clips
public float lowPitchMin = 1f; // The lowest possible pitch for the low sounds
public float lowPitchMax = 6f; // The highest possible pitch for the low sounds
public float highPitchMultiplier = 0.25f; // Used for altering the pitch of high sounds
public float maxRolloffDistance = 500; // The maximum distance where rollof starts to take place
public float dopplerLevel = 1; // The mount of doppler effect used in the audio
public bool useDoppler = true; // Toggle for using doppler
private AudioSource m_LowAccel; // Source for the low acceleration sounds
private AudioSource m_LowDecel; // Source for the low deceleration sounds
private AudioSource m_HighAccel; // Source for the high acceleration sounds
private AudioSource m_HighDecel; // Source for the high deceleration sounds
private bool m_StartedSound; // flag for knowing if we have started sounds
private CarController m_CarController; // Reference to car we are controlling
private void StartSound()
{
// get the carcontroller ( this will not be null as we have require component)
m_CarController = GetComponent<CarController>();
// setup the simple audio source
m_HighAccel = SetUpEngineAudioSource(highAccelClip);
// if we have four channel audio setup the four audio sources
if (engineSoundStyle == EngineAudioOptions.FourChannel)
{
m_LowAccel = SetUpEngineAudioSource(lowAccelClip);
m_LowDecel = SetUpEngineAudioSource(lowDecelClip);
m_HighDecel = SetUpEngineAudioSource(highDecelClip);
}
// flag that we have started the sounds playing
m_StartedSound = true;
}
private void StopSound()
{
//Destroy all audio sources on this object:
foreach (var source in GetComponents<AudioSource>())
{
Destroy(source);
}
m_StartedSound = false;
}
// Update is called once per frame
private void Update()
{
// get the distance to main camera
float camDist = (Camera.main.transform.position - transform.position).sqrMagnitude;
// stop sound if the object is beyond the maximum roll off distance
if (m_StartedSound && camDist > maxRolloffDistance*maxRolloffDistance)
{
StopSound();
}
// start the sound if not playing and it is nearer than the maximum distance
if (!m_StartedSound && camDist < maxRolloffDistance*maxRolloffDistance)
{
StartSound();
}
if (m_StartedSound)
{
// The pitch is interpolated between the min and max values, according to the car's revs.
float pitch = ULerp(lowPitchMin, lowPitchMax, m_CarController.Revs);
// clamp to minimum pitch (note, not clamped to max for high revs while burning out)
pitch = Mathf.Min(lowPitchMax, pitch);
if (engineSoundStyle == EngineAudioOptions.Simple)
{
// for 1 channel engine sound, it's oh so simple:
m_HighAccel.pitch = pitch*pitchMultiplier*highPitchMultiplier;
m_HighAccel.dopplerLevel = useDoppler ? dopplerLevel : 0;
m_HighAccel.volume = 1;
}
else
{
// for 4 channel engine sound, it's a little more complex:
// adjust the pitches based on the multipliers
m_LowAccel.pitch = pitch*pitchMultiplier;
m_LowDecel.pitch = pitch*pitchMultiplier;
m_HighAccel.pitch = pitch*highPitchMultiplier*pitchMultiplier;
m_HighDecel.pitch = pitch*highPitchMultiplier*pitchMultiplier;
// get values for fading the sounds based on the acceleration
float accFade = Mathf.Abs(m_CarController.AccelInput);
float decFade = 1 - accFade;
// get the high fade value based on the cars revs
float highFade = Mathf.InverseLerp(0.2f, 0.8f, m_CarController.Revs);
float lowFade = 1 - highFade;
// adjust the values to be more realistic
highFade = 1 - ((1 - highFade)*(1 - highFade));
lowFade = 1 - ((1 - lowFade)*(1 - lowFade));
accFade = 1 - ((1 - accFade)*(1 - accFade));
decFade = 1 - ((1 - decFade)*(1 - decFade));
// adjust the source volumes based on the fade values
m_LowAccel.volume = lowFade*accFade;
m_LowDecel.volume = lowFade*decFade;
m_HighAccel.volume = highFade*accFade;
m_HighDecel.volume = highFade*decFade;
// adjust the doppler levels
m_HighAccel.dopplerLevel = useDoppler ? dopplerLevel : 0;
m_LowAccel.dopplerLevel = useDoppler ? dopplerLevel : 0;
m_HighDecel.dopplerLevel = useDoppler ? dopplerLevel : 0;
m_LowDecel.dopplerLevel = useDoppler ? dopplerLevel : 0;
}
}
}
// sets up and adds new audio source to the gane object
private AudioSource SetUpEngineAudioSource(AudioClip clip)
{
// create the new audio source component on the game object and set up its properties
AudioSource source = gameObject.AddComponent<AudioSource>();
source.clip = clip;
source.volume = 0;
source.loop = true;
// start the clip from a random point
source.time = Random.Range(0f, clip.length);
source.Play();
source.minDistance = 5;
source.maxDistance = maxRolloffDistance;
source.dopplerLevel = 0;
return source;
}
// unclamped versions of Lerp and Inverse Lerp, to allow value to exceed the from-to range
private static float ULerp(float from, float to, float value)
{
return (1.0f - value)*from + value*to;
}
}
}