Antlions: Random Spawn

The great thing about these antlions is that they are made to be used with other litle tools to make them spawn randomly when the player walks on a specified material, be it sand or any other material.

This tutorial will walk you through the making of a simple example of randomly unburrowing antlions.

Getting started

First, make a map with sand and rocks. The situation we are attempting to create is that if the player walks on the sand, antlions come out near the player and attack, and the player is forced to walk on the rocks.

These are the entities we are going to need:

• npc_antlion
• env_shake
• ambient_generic
• npc_antlion_template_maker
• logic_relay
• env_player_surface_trigger
• info_node_hint

Configuring the entities

Italicized text is a flag. ---

Class: npc_antlion
Keyvalues		Comments
Name	AntLion

---

	Flag
	File:Checkbox-yes.png	Start Burrowed
	File:Checkbox-yes.png	Template NPC

Class: env_player_surface_trigger
Keyvalues		Comments
Name	SurfaceTrigger
GameMaterialToWatch	sand

This entity triggers inputs if the player is walking on the specified material.

Create the following outputs:

		My output	Target entity	Target input	Parameter	Delay	Only once	Comments
	File:Entity-output-iconOnSurfaceChangedFromTarget.png	relay_expanse_disablespawn	Trigger					{{{8}}}
	File:Entity-output-iconOnSurfaceChangedToTarget.png	relay_expanse_spawn	Trigger					{{{8}}}

Those mean that if the player starts walking on the surface we have chosen, it triggers the relay OnSurfaceChangedToTarget which enables the npc_antlion_template_maker, and after that that when (or if) the player steps off it, it triggers the relay OnSurfaceChangedFromTarget which stops the spawning.

Class: ambient_generic
Keyvalues		Comments
Name	sound_antlion_spawn
SoundName	Streetwar.d3_c17_10b_rumble1
Volume	8
Fade In Time	1.5
Fade Out Time	2
Pitch	120
Start Pitch	90
Max Audible Distance	1250

This entity creates the noise when the antlions are emerging.

Class: env_shake
Keyvalues		Comments
Name	shake_antlion_spawn
Amplitude	2
Effect Radius	500
Duration	3
Frequency	100

This entity creates the quake when the antlions are emerging.

npc_antlion_template_maker

Class: npc_antlion_template_maker
Keyvalues		Comments
Name	antlion_expanse_spawner
StartDisabled	Yes	....we do not want the template_maker to start spawning at the beginning of the map
Num. of NPCs		Leave empty because we will check Infinite Children in flags
Frequency	0.35
Max Live NCPs		how many antlions can live at same time, 8 for example
Name Of Template NPC	AntLion
Spawn On HintGroup	antlion_expanse_spawn_nodes
Spawn Radius	1000
Spawn Target	!player	the target that the antlions will attack
Ignore Bugbait	No

Now, remember to check:

	Flag
		Infinite Children

Then, add the following output:

		My output	Target entity	Target input	Parameter	Delay	Only once	Comments
	File:Entity-output-iconOnAllSpawnedDead.png	antlion_expanse_spawner	SetMaxChildren	8	9.00			{{{8}}}
								{{{8}}}

That means if all antlions are dead it resets the max number to 8 to prevent any problems.

Class: logic_relay
Keyvalues		Comments
Name	relay_expanse_spawn

Add the following outputs, the numbers this time meaning Delay:

		My output	Target entity	Target input	Parameter	Delay	Only once	Comments
	File:Entity-output-iconOnTrigger.png	sound_antlion_spawn	PlaySound					{{{8}}}
	File:Entity-output-iconOnTrigger.png	relay_expanse_disablespawn	CancelPending					{{{8}}}
	File:Entity-output-iconOnTrigger.png	shake_antlion_spawn	StartShake		0.10			{{{8}}}
	File:Entity-output-iconOnTrigger.png	antlion_expanse_spawner	Enable		1.00			{{{8}}}

This means if this relay is triggered it plays the sound, the ground shakes and the npc_antlion_template_maker enables 1 second after we walked on the ground, which makes an effect like the antlions are coming up.

Another...

Class: logic_relay
Keyvalues		Comments
Name	relay_expanse_disablespawn

Add the following outputs:

		My output	Target entity	Target input	Parameter	Delay	Only once	Comments
	File:Entity-output-iconOnTrigger.png	sound_antlion_spawn	StopSound					{{{8}}}
	File:Entity-output-iconOnTrigger.png	shake_antlion_spawn	StopShake					{{{8}}}
	File:Entity-output-iconOnTrigger.png	antlion_expanse_spawner	Disable		0.50			{{{8}}}
	File:Entity-output-iconOnTrigger.png	relay_expanse_spawn	CancelPending		0.50			{{{8}}}

This means if this relay is triggered, the sound stops, the shake stops and the template_maker disables.

Another group of entities:

Class: info_node_hint
Keyvalues		Comments
Hint	AntLion Burrow Point
Hint Group	antlion_expanse_spawn_nodes

These are to set where the antlions can spawn, you must put one everywere that the antlion can possibly spawn, and the npc_antlion_template_maker will pick the one nearest the player.

Notes

The antlions use info_node to navigate on the ground, and info_node_air to navigate while flying.

To make them follow a precise path, use path_corners and set it to the antlion's path corner, and place info_nodes around the way so the antlions can navigate through them.

If there is a wall in their way, put some info_node_airs about 10 units above it, the antlions will use it to fly above the wall.

Quick tutorial to making antlions follow a path

If you want the antlions to run to a precise target, use aiscripted_schedule, name it and configure:

Target Npc: Antlion

Search Radius: If there are more than one target, put 0.

All In Radius: If there are more than one target, put yes.

Ai State To Set: Choose one

Schedule to run: Choose one

Interruptability: Choose one

Goal Entity: Is the target, it can be one precise or a classname, like npc_citizen.

Then at the npc_antlion_template_maker, add the following output:

OnSpawnNpc, AiSchedule, StartSchedule

Example Map

Example map