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From HalfLife 2 Knowledge Base

by: Exitus

Precursor

Striders are one of the most formidable enemies in Half Life 2. You may remember them from the battle in front of the museum, or from various places in City 17. perhaps maybe you remember their reality-bending cannon from when you stared in awe as it blew up buildings? Want to do it yourself?

Well, this series of tutorials is going to cover the following things:

- Making striders walk

- Making striders crouch and walk under something and stand back up

- Making striders fire their reality-bending cannon

- Making a strider go on a war path

These 4 things will be split up into 3 tutorials.

Part I: Making a strider walk around, making striders crouch and walk under something and stand back up.

Part II: Making striders fire their reality-bending cannon, also making buildings blow up.

Part III: Making the strider war path. This will incorporate all previous tutorials and make one large path.

Setup

This step is optional, but it will make it easier for you to test the map. Create a ai_relationship somewhere in the map. For the Subject(s) field, enter npc_strider. for the Target(s) field, enter "player" without the quotes. Also be sure that the Start On is set to Yes.

This will make it so that the strider is freindly towards the player, and won't attack him.

Making a Strider Walk Around

The first thing you will need to do is to create an npc_strider. Give it name of "strider".

Next, create a path_corner very close to where the strider current is located. Give it the name of "path_strider_1". To make the path, hold down shift, and then drag the path to where you want the next one to be created. This will create the next path_corner, and automatically rename it to the next number and set the previous path_corner's "Next Stop Target" to the new one. Use this method until you have a path as long as you like.

Now, select the strider again and set its "Target path corner" to path_strider_1. Stick an info_player_start in the map, and go test it!

Oh Crap! It didn't work!

You will more then likely notice that the strider did not do anything. This is because a strider needs a path of info_node_air_hint that are close to the path_corners, so that the strider can navigate in between these paths. You might want to put these up in the air so that they are seperate from your path_corners. You then need to set the hint key to "Strider Node". This designates it as a strider node. Now, after adding these, go back into the game and try it again. It should work. If not, then you might want to make sure you followed these steps correctly.

Crouching Strider, Hidden Cannon

The next thing to learn about the striders is how to make them crouch under an obstacle. The first thin that you need to do is to make something for the strider to crouch under. Maybe it's a tunnel, or whatever, but for this tutorial, it will be a bridge. Make sure the opening is wide enough so that the strider's legs don't clip into geomatry when walking under the bridge.

Extend your path of the path_corners and info_node_air_hints so that they pass under the bridge. Make one of the path tracks close to the bridge. On this specific path_corner, your going to tell the strider to crouch when passing it.

Go to the outputs tab, and make a new one. Name the output "OnPass", make it target "strider" via the input of "crouch". This is the command to make it crouch.

Now, on the other side of the bridge, make a path_corner, and for its outputs, do the same thing you did as before, but for the input, use "stand" instead.

That's it for now!

Next: Striders_Part_II