View source for Sound sensitive trigger

This tutorial will explain the process of making a trigger that will detect sound levels in the surrounding area and go off. 

[[File:Soundsensitive first.jpg|thumb|300px|right]]

==Getting started==

First of all, you need a small area for this example. The area for this tutorial is a small courtyard, as shown on the right.

==Setting up the necessary entities==

We need something for the ''microphone'' to detect from. An <code>[[info_target]]</code> is what we will be using. Call it <code>microphone1</code>. In your map, it can be called anything you like. 

[[File:Soundsensitive second.jpg|thumb|300px|right]]

Then, create an <code>[[env_microphone]]</code>. This is the entity that will control the sound output level. Give it the following properties:

'''Classname''' : env_microphone
* '''Name : speaker''' In your map again, this can be anything at all.
* '''Measure Target : microphone1''' Make sure this is the name of your <code>[[info_target]]</code>, otherwise the <code>[[env_microphone]]</code> won't do  its sound checks correctly.
* '''Sensitivity : 2''' This should allow you to not be detected by crouching, but will detect you when you run or shoot.
* '''Maximum hearing range : 512''' This is the distance in units the <code>[[env_microphone]]</code> will hear.
* '''Spawnflags :'''
:* Hears combat sounds
:* Hears world sounds
:* Hears player sounds
:* Hears bullet impacts
:* Hears explosions

Now we need a <code>[[logic_compare]]</code> to test the sound levels. We need the following parameters for it:

'''Classname''' : logic_compare
* '''Name : spvol''' Our entity's name again, this entity checks the volume of the microphone and can trigger things.
* '''Initial value : 0''' This is what the <code>logic_compare</code> will compare all values to, and can trigger an output depending on various states.
* '''Compare value : 0.5''' This is the trigger level to trigger things from the sound level of the <code>env_microphone</code>.

Now we need to set up some of the entity I/O on our <code>env_microphone</code>. Add a new output to our <code>env_microphone</code> with the following options:

{| class=standard-table
|+Object outputs: speaker - env_microphone
!  || My Output || Target Entity || Target Input || Parameter || Delay || Only Once
|-
| [[File:Io11.png]] || SoundLevel || spvol || SetValueCompare || <none> || 0.00 || No
|}

[[File:Soundsensitive third.jpg|thumb|300px|right]]

==Making the trigger==

The final step now is to set up the output of the <code>logic_compare</code> to trigger something. This can be open a door, turn on a light, break a rope, anything that can take an entity I/O input. In this case we will rig up an alarm.

'''Output''':
* OnGreaterThan: This gets triggered when the sound level is past the trigger level.
* OnLessThan: This gets triggered when the sound level is under the trigger level.

Now you should have a working sound sensitive trigger!

==External links==

* [http://loz.snarkcafe.net/maps/HL2/soundsensitive_trigger.zip Example map]

[[Category:Level Design]]
[[Category:Tutorials]]