Inputs and Outputs: Difference between revisions

Latest revision as of 18:44, 14 May 2025

Inputs and Outputs (collectively "I/O") are the means by which entities communicate between each other in maps. Entities have two methods for communication: sending an "output" to another entity, or receiving an "input" from another entity. For example, one entity may send an output when it is killed to another entity's input which causes it to change color. That same output could also be used to trigger another entity's spawning input. The outputs are matched to the inputs via a "connection", which controls what extra data is relayed to the receiver, how much of a delay there is before the output is received, and whether the output should be allowed to be sent again later. Outputs can be linked to any input and vice versa. This allows complex and powerful interactions between entities.

Consider a logic_timer entity. It might be configured to "fire" its OnTimer output when it hits its time limit, which "triggers" (or "calls") the ShowSprite input of an env_sprite. When the timer hits its limit, the sprite appears. By using the connection properties, you could also cause the output to be triggered after a two second delay, or to trigger once but never again.

Inputs

Inputs are commands that cause an entity to change what it is doing. They are "triggered" (or "called") by outputs - they cannot be manipulated directly.

You can view a list of input events that an entity is receiving in the Inputs tab of the object properties dialog. Clicking the "mark" button will take you to the entity that the input is being received from.

Outputs

Hammer's "Object Properties" dialog

Outputs are events that fire when an entity's state changes. For example, a timer will have an output for reaching its end, a button an output for being pressed, and a door an output for coming to a close.

Output events are created in the Outputs tab of the object properties dialog. This interface provides a list of the outputs already emitting from the entity, configuration fields for the one(s) currently selected, and buttons for creating new and deleting old. Finally, the button in the bottom left labelled "mark" will take you to the target entity of the current output.

The output configuration fields are:

Output name: What event causes the output to fire. For example, a trigger_multiple entity can fire an OnTrigger output when a player steps into it.

Target entity

The targetname or classname of the entity that will receive input. Accepts the * character as a search wildcard.

A bold name means that the targetname points to multiple entities
A red name means that the targetname doesn't point to anything
Warning:Valid classname, wildcard values or special targetnames will also appear red. Don't worry: the engine will recognise them!

Input name: The input on the target entity that will be triggered. This too will be context sensitive. For example, if sending an output to a Door entity, some of the available inputs will be "Close" or "Open".

Parameters: You can pass data to the target entity with parameters. A parameter might be anything: how loud to play a sound, the targetname of another entity, or perhaps a color. It all depends on what the input accepts. If it doesn't accept anything, this field will be greyed out.; Some outputs, like math_counter's OutValue, generate parameters themselves. To use a generated parameter, just leave the field reading <none>.
Note:If the output value is a targetname, remember that it may not be unique!

Time delay: The number of seconds to wait after the output event occurs before firing.

Fire once only: The output will be deleted after it fires if this is checked.

Setting up a simple trigger

This is an example of how to make a simple trigger using inputs and outputs, so a sound is played when the player enters a specific area.

Open up a map and add an ambient_generic (in the Name field, type in "ambient_1"). Go into its Object Properties and choose a sound file for it to play, and on the Flags tab make it set to "Start Silent". Select the "tools/toolstrigger" texture and create a cube brush with this texture. Right-click on this brush and using the "Tie to Entity" command, make it into a trigger_once entity. Go to the Outputs tab and click the Add... button.

Set "My output named" to "OnStartTouch". This causes the output (and thus the trigger) to occur when the player starts touching this brush in the game.

Set "Targets entities named" to "ambient_1" using the pull-down arrow. This makes the trigger output target the ambient_generic you placed earlier.

Set "Via this input" to "PlaySound". This chooses the PlaySound action from the target ambient_generic's list of actions, which of course causes its sound to start playing.

Click the Apply button to save your changes to the trigger, and close it. Now we have the trigger set up so that as soon as the player touches it, it sends a command to the ambient_generic which makes it start playing its sound.

If you open up the properties for the ambient_generic, you can see how the Output from the trigger has automatically been converted to an Input for the ambient_generic.

If you want to compile and test your new trigger, make sure you have all the basics (player start, lighting, etc) and have assigned a sound effect to the ambient_generic.

Debugging

Source provides various debugging tools for when an I/O chain is not working as expected.

Foremost among them is the object properties dialog itself. Invalid inputs outputs are highlighted red (see Target entity warning ↑) in the entity's input or output list; the I/O icons at the bottom of the dialoge also change accordingly. Invalid outputs also show up in Check For Problems (Alt+P). It's a good idea check for problems before every compile.

Away from Hammer, there are a number of console commands and variables that will help you spot errors while your map is running:

Cvar/Command	Parameters or default value	Descriptor	Effect
`developer`	`0`	integer	If set to 2 or higher all entity I/O events will be reported to the console (see developer for more info)
`dumpeventqueue`		void	Dumps IO event queue to console
`ent_messages_draw`	`0`	bool	This displays the same information as developer mode, except that instead of appearing in the console it's drawn in the 3D world at the location of the entities in question.
`ent_fire`	`<target> <input> [parameter] [delay]`		This extremely useful command allows you to manually fire inputs on any entity at any time. If you want to unlock a door ahead of time, you would type `ent_fire my_door unlock`, followed if you're feeling lazy by `ent_fire my_door open`. Like the "output target" field in Hammer, `ent_fire` supports classnames and wildcards. If you want to `ent_fire npc_* ignite`, you can! Tip:`ent_fire` is where the special `!picker` targetname comes in. Use it to target whatever is under your crosshair.
`ent_pause`		void	This command pauses all entities in the map except the player; submit it again to unpause. It is designed for use with `ent_step`.
`ent_step`	`[number of steps (default 1)]`	integer	When used with `ent_pause`, this command makes entities perform a specified number of I/O steps before pausing again

@@ Line 1: / Line 1: @@
-[[Category:Level Design]]
+{{LanguageBar}}
-One of the most important changes to map making for the Source engine has been Entity I/O. Whereas older versions of the engine relied on the <code>target</code> and <code>targetname</code> keyfields to send simple impulses to an entity, the entity I/O system allows for complex communication between entities. This is done using entity <i>inputs</i> and <i>outputs</i>, that are joined by <i>connections</i>. Using this simple method, entities can easily trigger events based on state changes and work in tandem with other entities in a more atomic, logical and powerful way than previously possible.
+{{Source topicon}}
+{{toc-right}}
+'''Inputs''' and '''Outputs''' (collectively "I/O") are the means by which [[Entity|entities]] communicate between each other in [[:Category:Level Design|maps]]. Entities have two methods for communication: sending an "output" to another entity, or receiving an "input" from another entity. For example, one entity may send an output when it is killed to another entity's input which causes it to change color. That same output could also be used to trigger another entity's spawning input. The outputs are matched to the inputs via a "connection", which controls what extra data is relayed to the receiver, how much of a delay there is before the output is received, and whether the output should be allowed to be sent again later. Outputs can be linked to any input and vice versa. This allows complex and powerful interactions between entities.
+Consider a [[logic_timer]] entity. It might be configured to "fire" its <code>OnTimer</code> output when it hits its time limit, which "triggers" (or "calls") the <code>ShowSprite</code> input of an [[env_sprite]]. When the timer hits its limit, the sprite appears. By using the connection properties, you could also cause the output to be triggered after a two second delay, or to trigger once but never again.
+== Inputs ==
+'''Inputs''' are commands that cause an entity to change what it is doing. They are "triggered" (or "called") by outputs - they cannot be manipulated directly.
+You can view a list of input events that an entity is receiving in the Inputs tab of the [[Hammer Object Properties Dialog|object properties dialog]]. Clicking the "mark" button will take you to the entity that the input is being received from.
+== Outputs ==
+[[File:Outputs-new.png|thumb|Hammer's "Object Properties" dialog]]
+'''Outputs''' are events that fire when an entity's state changes. For example, a [[logic_timer|timer]] will have an output for reaching its end, a [[func_button|button]] an output for being pressed, and a [[prop_door_rotating|door]] an output for coming to a close.
+Output events are created in the Outputs tab of the [[Hammer Object Properties Dialog|object properties dialog]]. This interface provides a list of the outputs already emitting from the entity, configuration fields for the one(s) currently selected, and buttons for creating new and deleting old. Finally, the button in the bottom left labelled "mark" will take you to the target entity of the current output.
+The output configuration fields are:
+; Output name
+: What event causes the output to fire. For example, a [[trigger_multiple]] entity can fire an '''OnTrigger''' output when a player steps into it.
+; Target entity <span id="Target entity" />
+: The [[targetname]] or [[classname]] of the entity that will receive input. Accepts the * character as a search wildcard.
+:* A bold name means that the targetname points to multiple entities
+:* A red name means that the targetname doesn't point to anything {{warning|Valid classname, wildcard values or [[Targetname#Keywords|special targetnames]] will also appear red. Don't worry: the engine will recognise them!}}
+; Input name
+: The input on the target entity that will be triggered. This too will be context sensitive. For example, if sending an output to a Door entity, some of the available inputs will be "Close" or "Open".
+; Parameters
+: You can pass data to the target entity with parameters. A parameter might be anything: how loud to play [[ambient_generic|a sound]], the [[targetname]] of another entity, or perhaps [[color255|a color]]. It all depends on what the input accepts. If it doesn't accept anything, this field will be greyed out.
+: Some outputs, like [[math_counter]]'s <code>OutValue</code>, generate parameters themselves. To use a generated parameter, just leave the field reading <code><none></code>. {{note|If the output value is a [[targetname]], remember that it may not be unique!}}
+; Time delay
+: The number of seconds to wait after the output event occurs before firing.
-=Overview=
+; Fire once only
+: The output will be deleted after it fires if this is checked.
-Entities have two methods for communication: sending an <i>output</i> to another entity, or receiving an <i>input</i> from another entity. One entity may send an output when it is killed to another entity's input which causes it to change color. That same output could also be used to trigger another entity's spawning input. The outputs are matched to the inputs via a <i>connection</i>, which controls what extra data is relayed to the receiver, how much of a delay there is before the output is received, and whether the output should be allowed to be sent again later. Outputs can be linked to any input and vice versa. This allows complex and powerful interactions between entities.
+== Setting up a simple trigger ==
+This is an example of how to make a simple trigger using inputs and outputs, so a sound is played when the player enters a specific area.
-As an example, a <code>[[logic_timer]]</code> entity may send an <code>OnTimer</code> output, which triggers when the time condition is met for the entity. That output might be hooked to the <code>Show</code> input on an <code>[[env_sprite]]</code>, causing it to become visible when the timer has reached its desired time. You could also hook the <code>OnTimer</code> output for the <code>[[logic_timer]]</code> to a <code>SparkOnce</code> input on an <code>[[env_spark]]</code> to cause it to emit sparks. By using the connection properties, you could also cause the output to be triggered after a two second delay, or to trigger once but never again.
+Open up a map and add an [[ambient_generic]] (in the Name field, type in "<code>ambient_1</code>"). Go into its '''Object Properties''' and choose a sound file for it to play, and on the '''Flags''' tab make it set to "'''Start Silent'''". Select the "<code>tools/toolstrigger</code>" texture and create a cube brush with this texture. Right-click on this brush and using the "[[Brush entity|Tie to Entity]]" command, make it into a [[trigger_once]] entity. Go to the '''Outputs''' tab and click the '''Add...''' button.
-For users more familiar with the original Half-Life method of entity communication, the <code>targetname</code> and <code>target</code> fields are now obsolete and the entity I/O system is a superset of that functionality. Instead of a <code>[[trigger_multiple]]</code> entity only firing its target entity, it may now use any number of its outputs to do the same, including: <code>OnStartTouch</code>, <code>OnEndTouch</code>, <code>OnTouch</code>, etc. These outputs may be connected to an arbitrary number of entities all at once with unique delays per output, making <i>multi-managers</i> obsolete as well. Likewise, the <code>killtarget</code> field is now replaced by connecting an output to the <code>Kill</code> input of another entity.
+Set "My output named" to "<code>OnStartTouch</code>". This causes the output (and thus the trigger) to occur when the player starts touching this brush in the game.
-=Outputs=
+Set "Targets entities named" to "<code>ambient_1</code>" using the pull-down arrow. This makes the trigger output target the <code>ambient_generic</code> you placed earlier.
-Outputs are events that are fired when an entity's state changes. This could be a timer reaching its end, a button being pressed or a door coming to a close. Any number of outputs can be specified by a programmer internally in an entity to trigger on any number of criteria. Specifying outputs is done in the '''Outputs''' tab in an entity's properties. The '''Ouputs''' tab of the '''Object Properties''' dialog displays all the outputs that are connected from this entity to other entities.
+Set "Via this input" to "<code>PlaySound</code>". This chooses the <code>PlaySound</code> action from the target <code>ambient_generic</code>'s list of actions, which of course causes its sound to start playing.
-[[Image:hammer_entityio1.jpg]]
+Click the '''Apply''' button to save your changes to the trigger, and close it. Now we have the trigger set up so that as soon as the player touches it, it sends a command to the <code>ambient_generic</code> which makes it start playing its sound.
-# The method in which the output is triggered*.
-# Name of the entity to receive the output (click an entity with Eye Dropper tool to paste its name here).
-# Input(entity) that will receive the output.  This is where you will choose what action the entity will do.  For instance if you want a soldier to rappel you enter the beginrappel command.
-# Parameter override to use if data is accepted by the target input. Often this is a number used by the input function (see Inputs section below).
-# Amount to delay sending the output (in seconds). 1/10th of a second is expressed as "0.1" seconds.
-# Whether to only fire the output once.
- *Sample Triggers
-   OnTrigger-When another trigger is triggered, it will set off the curent one
-   OnMapSpawn-When this map is loaded the trigger will go off immediately
-=Inputs=
+If you open up the properties for the <code>ambient_generic</code>, you can see how the '''Output''' from the trigger has automatically been converted to an '''Input''' for the <code>ambient_generic</code>.
-[[Image:hammer_entityio2.jpg]]
+If you want to compile and test your new trigger, make sure you have all the basics (player start, lighting, etc) and have assigned a sound effect to the <code>ambient_generic</code>.
-Inputs connect to outputs of any type. Here we see the '''Inputs''' tab on the '''Object Properties''' dialog. It shows all of the outputs that are connected from other entities to this entity.
+== Debugging ==
+Source provides various debugging tools for when an I/O chain is not working as expected.
-Because any output can connect to any input, there are a multitude of combinations that can be used to make complex interaction occur. Timers can orchestrate a countdown sequence using blinking sprites, sounds and special effects all without any need for special entities. By clicking the '''Mark''' button or double-clicking on an entry in the list, the user is able to go to the entity sending the output to the input in question.
+Foremost among them is the object properties dialog itself. Invalid inputs outputs are highlighted red ({{↑|Target entity|see Target entity warning}}) in the entity's input or output list; the I/O icons at the bottom of the dialoge also change accordingly. Invalid outputs also show up in [[Hammer Check For Problems Dialog|Check For Problems]] ({{key|Alt+P}}). It's a good idea check for problems before every compile.
-If a connection is displayed in red, it is invalid. This means that either the output does not exist in the source entity, or the input is not present in the destination entity. Invalid connections are benign but should be fixed before map compilation because the '''Check For Problems''' menu command will report them as an error.
+Away from Hammer, there are a number of [[Developer console|console]] commands and variables that will help you spot errors while your map is running:
-=Debugging=
+{{varcom|start}}
+{{varcom|[[developer]]|0|integer|If set to 2 or higher all entity I/O events will be reported to the console (see [[developer]] for more info)}}
+{{varcom|dumpeventqueue||void|Dumps IO event queue to console}}
+{{varcom|ent_messages_draw|0|bool|This displays the same information as developer mode, except that instead of appearing in the console it's drawn in the 3D world at the location of the entities in question.}}
+{{varcom|[[ent_fire]]|<[[targetname|target]]>&nbsp;<input>&nbsp;[parameter]&nbsp;[delay]||This ''extremely'' useful command allows you to manually fire inputs on any entity at any time. If you want to unlock a door ahead of time, you would type <code>ent_fire my_door unlock</code>, followed if you're feeling lazy by <code>ent_fire my_door open</code>.
+: Like the "output target" field in Hammer, <code>ent_fire</code> supports classnames and wildcards. If you want to <code>ent_fire npc_* ignite</code>, you can! {{tip|<code>ent_fire</code> is where the special <code>[[!picker]]</code> targetname comes in. Use it to target whatever is under your crosshair.}}
+}}
+{{varcom|ent_pause||void|This command pauses all entities in the map except the player; submit it again to unpause. It is designed for use with <code>ent_step</code>.}}
+{{varcom|ent_step|[number of steps (default 1)]|integer|When used with <code>ent_pause</code>, this command makes entities perform a specified number of I/O steps before pausing again}}
+{{varcom|end}}
-Because the nature of how entities communicate has become more complex and powerful, so too has the debugging capabilities of the engine to help you track down problems. If a chain of I/O logic is not working as expected, the tools below will aid greatly in solving the error.
+== See also ==
+* [[Data Descriptions]] - Some information on how inputs and outputs function internally can be found here.
+* [[Entity creation]]
+* [[List of entities]]
+* [[Targetname]]
+* [[User Inputs and Outputs]]
+* [[AddOutput]]
+* [[Entity parameters inputs outputs]] - List of entities parameters, Inputs and Outputs (Advanced stuff)
-{|
+[[Category:IO System]]
-| <code>ent_developer</code>
+[[Category:Level Design]]
-|-
-| By setting this console variable to a value of "2", you'll receive a detailed log of how the entities are interacting via the entity I/O system. This is useful for seeing the exact chain of events taking place in complex interactions.
-|}
-{|
-| <code>ent_messages_draw</code>
-|-
-| Setting this console variable to a value of "1" will display visual information about how entities are communicating with one another. This is very similar to using the ent_developer console variable, but can sometimes be more immediately intuitive to the viewer.
-|}
-{|
-|<code>ent_fire (<i>entity name</i>, <i>input name</i>, <i>input value</i>)</code>
-|-
-| This console command allows you to manually fire inputs on an entity from the console. This can be very useful for testing settings for entities in realtime. To fire the "Open" input for an entity named "testentity" with an input parameter of "3", you would type: <i>ent_fire testentity open 3</i>
-|}
-{|
-| <code>ent_pause</code>
-|-
-| This command pauses entities in the map. If entered again, the entities will resume their normal behavior. This is most useful when use with the <i>ent_step</i> command, described below.
-|}
-{|
-| <code>ent_step</code>
-|-
-| When used with the <i>ent_pause</i> console command, this command allows the user to slowly step through an entity's chain of execution for input and output. Any number of steps can be iterated through at one time, as specified by a value entered after the command (i.e. <i>"ent_step 3"</i> would execute three steps at once).
-|}

Inputs and Outputs: Difference between revisions

Latest revision as of 18:44, 14 May 2025

Contents

Inputs

Outputs

Setting up a simple trigger

Debugging

See also

Navigation menu

Inputs and Outputs: Difference between revisions

Latest revision as of 18:44, 14 May 2025

Inputs

Outputs

Setting up a simple trigger

Debugging

See also

Navigation menu

Search