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

Cursive text is a flag.

npc_antlion

Name: AntLion

Starts Burrowed: yes

env_player_surface_trigger

Name: SurfaceTrigger

GameMaterialToWatch: sand

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

Create the following outputs:

OnSurfaceChangedFromTarget, relay_expanse_disablespawn, Trigger OnSurfaceChangedToTarget, relay_expanse_spawn, Trigger

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.

ambient_generic

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.

env_shake

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

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 Infinite Children.

Then, add the following output:

OnAllSpawnedDead, antlion_expanse_spawner, SetMaxChildren, 8, 8.00

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

logic_relay

Name: relay_expanse_spawn

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

OnTrigger, sound_antlion_spawn, PlaySound OnTrigger, relay_expanse_disablespawn, CancelPending OnTrigger, shake_antlion_spawn, StartShake, 0.10 OnTrigger, antlion_expanse_spawner, Enable, 1.00

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 logic_relay

Name: relay_expanse_disablespawn

Add the following outputs, the numbers meaning Delay again:

OnTrigger, sound_antlion_spawn, StopSound OnTrigger, shake_antlion_spawn, StopShake OnTrigger, antlion_expanse_spawner, Disable, 0.50 OnTrigger, relay_expanse_spawn, CancelPending, 0.50

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

info_node_hint

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.

Hint: AntLion Burrow Point

Hint Group: antlion_expanse_spawn_nodes

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