1 using System;
2 using UnityEngine;
3 using Random = UnityEngine.Random;
4
5 namespace UnityStandardAssets.Vehicles.Car
6 {
7 [RequireComponent(typeof (CarController))]
8 public class CarAudio : MonoBehaviour
9 {
10 // This script reads some of the car's current properties and plays sounds accordingly.
11 // The engine sound can be a simple single clip which is looped and pitched, or it
12 // can be a crossfaded blend of four clips which represent the timbre of the engine
13 // at different RPM and Throttle state.
14
15 // the engine clips should all be a steady pitch, not rising or falling.
16
17 // when using four channel engine crossfading, the four clips should be:
18 // lowAccelClip : The engine at low revs, with throttle open (i.e. begining acceleration at very low speed)
19 // highAccelClip : Thenengine at high revs, with throttle open (i.e. accelerating, but almost at max speed)
20 // lowDecelClip : The engine at low revs, with throttle at minimum (i.e. idling or engine-braking at very low speed)
21 // highDecelClip : Thenengine at high revs, with throttle at minimum (i.e. engine-braking at very high speed)
22
23 // For proper crossfading, the clips pitches should all match, with an octave offset between low and high.
24
25
26 public enum EngineAudioOptions // Options for the engine audio
27 {
28 Simple, // Simple style audio
29 FourChannel // four Channel audio
30 }
31
32 public EngineAudioOptions engineSoundStyle = EngineAudioOptions.FourChannel;// Set the default audio options to be four channel
33 public AudioClip lowAccelClip; // Audio clip for low acceleration
34 public AudioClip lowDecelClip; // Audio clip for low deceleration
35 public AudioClip highAccelClip; // Audio clip for high acceleration
36 public AudioClip highDecelClip; // Audio clip for high deceleration
37 public float pitchMultiplier = 1f; // Used for altering the pitch of audio clips
38 public float lowPitchMin = 1f; // The lowest possible pitch for the low sounds
39 public float lowPitchMax = 6f; // The highest possible pitch for the low sounds
40 public float highPitchMultiplier = 0.25f; // Used for altering the pitch of high sounds
41 public float maxRolloffDistance = 500; // The maximum distance where rollof starts to take place
42 public float dopplerLevel = 1; // The mount of doppler effect used in the audio
43 public bool useDoppler = true; // Toggle for using doppler
44
45 private AudioSource m_LowAccel; // Source for the low acceleration sounds
46 private AudioSource m_LowDecel; // Source for the low deceleration sounds
47 private AudioSource m_HighAccel; // Source for the high acceleration sounds
48 private AudioSource m_HighDecel; // Source for the high deceleration sounds
49 private bool m_StartedSound; // flag for knowing if we have started sounds
50 private CarController m_CarController; // Reference to car we are controlling
51
52
53 private void StartSound()
54 {
55 // get the carcontroller ( this will not be null as we have require component)
56 m_CarController = GetComponent<CarController>();
57
58 // setup the simple audio source
59 m_HighAccel = SetUpEngineAudioSource(highAccelClip);
60
61 // if we have four channel audio setup the four audio sources
62 if (engineSoundStyle == EngineAudioOptions.FourChannel)
63 {
64 m_LowAccel = SetUpEngineAudioSource(lowAccelClip);
65 m_LowDecel = SetUpEngineAudioSource(lowDecelClip);
66 m_HighDecel = SetUpEngineAudioSource(highDecelClip);
67 }
68
69 // flag that we have started the sounds playing
70 m_StartedSound = true;
71 }
72
73
74 private void StopSound()
75 {
76 //Destroy all audio sources on this object:
77 foreach (var source in GetComponents<AudioSource>())
78 {
79 Destroy(source);
80 }
81
82 m_StartedSound = false;
83 }
84
85
86 // Update is called once per frame
87 private void Update()
88 {
89 // get the distance to main camera
90 float camDist = (Camera.main.transform.position - transform.position).sqrMagnitude;
91
92 // stop sound if the object is beyond the maximum roll off distance
93 if (m_StartedSound && camDist > maxRolloffDistance*maxRolloffDistance)
94 {
95 StopSound();
96 }
97
98 // start the sound if not playing and it is nearer than the maximum distance
99 if (!m_StartedSound && camDist < maxRolloffDistance*maxRolloffDistance)
100 {
101 StartSound();
102 }
103
104 if (m_StartedSound)
105 {
106 // The pitch is interpolated between the min and max values, according to the car's revs.
107 float pitch = ULerp(lowPitchMin, lowPitchMax, m_CarController.Revs);
108
109 // clamp to minimum pitch (note, not clamped to max for high revs while burning out)
110 pitch = Mathf.Min(lowPitchMax, pitch);
111
112 if (engineSoundStyle == EngineAudioOptions.Simple)
113 {
114 // for 1 channel engine sound, it's oh so simple:
115 m_HighAccel.pitch = pitch*pitchMultiplier*highPitchMultiplier;
116 m_HighAccel.dopplerLevel = useDoppler ? dopplerLevel : 0;
117 m_HighAccel.volume = 1;
118 }
119 else
120 {
121 // for 4 channel engine sound, it's a little more complex:
122
123 // adjust the pitches based on the multipliers
124 m_LowAccel.pitch = pitch*pitchMultiplier;
125 m_LowDecel.pitch = pitch*pitchMultiplier;
126 m_HighAccel.pitch = pitch*highPitchMultiplier*pitchMultiplier;
127 m_HighDecel.pitch = pitch*highPitchMultiplier*pitchMultiplier;
128
129 // get values for fading the sounds based on the acceleration
130 float accFade = Mathf.Abs(m_CarController.AccelInput);
131 float decFade = 1 - accFade;
132
133 // get the high fade value based on the cars revs
134 float highFade = Mathf.InverseLerp(0.2f, 0.8f, m_CarController.Revs);
135 float lowFade = 1 - highFade;
136
137 // adjust the values to be more realistic
138 highFade = 1 - ((1 - highFade)*(1 - highFade));
139 lowFade = 1 - ((1 - lowFade)*(1 - lowFade));
140 accFade = 1 - ((1 - accFade)*(1 - accFade));
141 decFade = 1 - ((1 - decFade)*(1 - decFade));
142
143 // adjust the source volumes based on the fade values
144 m_LowAccel.volume = lowFade*accFade;
145 m_LowDecel.volume = lowFade*decFade;
146 m_HighAccel.volume = highFade*accFade;
147 m_HighDecel.volume = highFade*decFade;
148
149 // adjust the doppler levels
150 m_HighAccel.dopplerLevel = useDoppler ? dopplerLevel : 0;
151 m_LowAccel.dopplerLevel = useDoppler ? dopplerLevel : 0;
152 m_HighDecel.dopplerLevel = useDoppler ? dopplerLevel : 0;
153 m_LowDecel.dopplerLevel = useDoppler ? dopplerLevel : 0;
154 }
155 }
156 }
157
158
159 // sets up and adds new audio source to the gane object
160 private AudioSource SetUpEngineAudioSource(AudioClip clip)
161 {
162 // create the new audio source component on the game object and set up its properties
163 AudioSource source = gameObject.AddComponent<AudioSource>();
164 source.clip = clip;
165 source.volume = 0;
166 source.loop = true;
167
168 // start the clip from a random point
169 source.time = Random.Range(0f, clip.length);
170 source.Play();
171 source.minDistance = 5;
172 source.maxDistance = maxRolloffDistance;
173 source.dopplerLevel = 0;
174 return source;
175 }
176
177
178 // unclamped versions of Lerp and Inverse Lerp, to allow value to exceed the from-to range
179 private static float ULerp(float from, float to, float value)
180 {
181 return (1.0f - value)*from + value*to;
182 }
183 }
184 }
