AudioEmitter.cs

Go to the documentation of this file.

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

using System;
using System.Collections.Generic;
using UnityEngine;

namespace HoloToolkit.Unity
{
    [DisallowMultipleComponent]
    [RequireComponent(typeof(AudioSource))]
    public class AudioEmitter : MonoBehaviour
    {
        public static readonly float NeutralLowFrequency = 10.0f;

        public static readonly float NeutralHighFrequency = 22000.0f;

        [Tooltip("Time, in seconds, between audio influence updates.  0 indicates to update every frame.")]
        [Range(0.0f, 1.0f)]
        [SerializeField]
        private float updateInterval = 0.25f;
        public float UpdateInterval
        {
            get { return updateInterval; }
            set
            {
                // set updateInterval and enforce the specified range
                if (value < 0.0f)
                {
                    updateInterval = 0.0f;
                }
                else if (value > 1.0f)
                {
                    updateInterval = 1.0f;
                }
                else
                {
                    updateInterval = value;
                }
            }
        }

        [Tooltip("Maximum distance, in meters, to look when attempting to find the user and any influencers.")]
        [Range(1.0f, 50.0f)]
        [SerializeField]
        private float maxDistance = 20.0f;
        public float MaxDistance
        {
            get { return maxDistance; }
            set
            {
                // set maxDistance and enforce the specified range
                if (value < 1.0f)
                {
                    maxDistance = 1.0f;
                }
                else if (value > 50.0f)
                {
                    maxDistance = 50.0f;
                }
                else
                {
                    maxDistance = value;
                }
            }
        }

        [Tooltip("Maximum number of objects that will be considered when looking for influencers.")]
        [Range(1, 25)]
        [SerializeField]
        private int MaxObjects = 10;

        private DateTime lastUpdate = DateTime.MinValue;

        private AudioSource audioSource;

        private float initialAudioSourceVolume;

        private RaycastHit[] hits;

        private List<IAudioInfluencer> previousInfluencers = new List<IAudioInfluencer>();

        private AudioLowPassFilter lowPassFilter;
        private float nativeLowPassCutoffFrequency;
        private AudioHighPassFilter highPassFilter;
        private float nativeHighPassCutoffFrequency;

        private void Awake() 
        {           
            audioSource = gameObject.GetComponent<AudioSource>();
            initialAudioSourceVolume = audioSource.volume;

            // Get optional filters (and initial values) that the sound designer / developer 
            // may have applied to this game object
            lowPassFilter = gameObject.GetComponent<AudioLowPassFilter>();
            nativeLowPassCutoffFrequency = (lowPassFilter != null) ? lowPassFilter.cutoffFrequency : NeutralHighFrequency;
            highPassFilter = gameObject.GetComponent<AudioHighPassFilter>();
            nativeHighPassCutoffFrequency = (highPassFilter != null) ? highPassFilter.cutoffFrequency : NeutralLowFrequency;

            // Preallocate the array that will be used to collect RaycastHit structures.
            hits = new RaycastHit[MaxObjects];
        }
    
        private void Update() 
        {
            DateTime now = DateTime.Now;

            // Audio influences are not updated every frame.
            if ((UpdateInterval * 1000.0f) <= (now - lastUpdate).Milliseconds)
            {
                audioSource.volume = initialAudioSourceVolume;

                // Get the audio influencers that should apply to the audio source.
                List<IAudioInfluencer> influencers = GetInfluencers();
                foreach (IAudioInfluencer influencer in influencers)
                {
                    // Apply the influencer's effect.
                    influencer.ApplyEffect(gameObject);
                }

                // Find and remove the audio influencers that are to be removed from the audio source.
                List<IAudioInfluencer> influencersToRemove = new List<IAudioInfluencer>();
                foreach (IAudioInfluencer prev in previousInfluencers)
                {
                    MonoBehaviour mbPrev = prev as MonoBehaviour;

                    // Remove influencers that are no longer in line of sight
                    // OR
                    // Have been disabled
                    if (!influencers.Contains(prev) ||
                        ((mbPrev != null) && !mbPrev.isActiveAndEnabled))
                    {
                        influencersToRemove.Add(prev);
                    }
                }
                RemoveInfluencers(influencersToRemove);

                previousInfluencers = influencers;
                lastUpdate = now;
            }
        }

        private void RemoveInfluencers(List<IAudioInfluencer> influencers)
        {
            foreach (IAudioInfluencer influencer in influencers)
            {
                influencer.RemoveEffect(gameObject);
            }
        }

        private List<IAudioInfluencer> GetInfluencers()
        {
            List<IAudioInfluencer> influencers = new List<IAudioInfluencer>();
            Transform cameraTransform = CameraCache.Main.transform;

            // Influencers take effect only when between the emitter and the user.
            // Perform a raycast from the user toward the object.
            Vector3 direction = (gameObject.transform.position - cameraTransform.position).normalized;
            float distance = Vector3.Distance(cameraTransform.position, gameObject.transform.position);

            int count = Physics.RaycastNonAlloc(cameraTransform.position,
                                                direction,
                                                hits,
                                                distance,
                                                Physics.DefaultRaycastLayers,
                                                QueryTriggerInteraction.Ignore);
            
            for (int i = 0; i < count; i++)
            {
                IAudioInfluencer influencer = hits[i].collider.gameObject.GetComponentInParent<IAudioInfluencer>();
                if (influencer != null)
                {
                    influencers.Add(influencer);
                }
            }

            return influencers;
        }

        public float GetNativeLowPassCutoffFrequency()
        {
            return nativeLowPassCutoffFrequency;
        }

        public void SetNativeLowPassCutoffFrequency(float frequency)
        {
            nativeLowPassCutoffFrequency = frequency;
        }

        public float GetNativeHighPassCutoffFrequency()
        {
            return nativeHighPassCutoffFrequency;
        }

        public void SetNativeHighPassCutoffFrequency(float frequency)
        {
            nativeHighPassCutoffFrequency = frequency;
        }
    }
}