This is the third HL2 Trains tutorial.
1) HL2 Player Controllable Trains
2) HL2 Automated Trains
3) HL2 Synchronized Trains
(The one you’re reading now.)

In this one I’m only going to cover the aspects needed for synchronized trains in HL2 which were not mentioned in parts 1 or 2.

Note: I’ve also included a CS:S version in the download below.
The CS:S version doesn’t include Alyx, naturally, or the moving ropes.
The moving ropes are somewhat of a problem in CS:S, however there is a method you can use to overcome it.
I haven’t created a tutorial for that but the CS:S Drawbridge I created, on the Files page, uses a method to overcome this problem.
The other ropes in this project work in either HL2/HL2DM or CS:S.

One more note about Ropes in any Source game. . .
A lot of people E-Mail me and ask why their ropes don’t hold anything.
Ropes are illusionary, they are not solid and do not constrain anything, they are for appearance only.

The first consideration for HL2 trains that are synchronized, move together, is to space them properly, or as you learned in the previous 2 train tutorials we need to space the starting path_track's properly, as the trains will spawn on the path_track they are assigned to.

In the image below you can see how the 4 trains in this tutorial are spaced, and the 4 path_track’s that are assigned to each of them.


Even more important is the way these trains are controlled, start, change speed and stop, together.

The method I’ve used to lock the player in the first train is very important.
As you can see in the 3D and 2D Top view ports, below, the player spawns in an invisible set of brushes.


These are all func_brush textured entirely with nodraw, tools/toolsnodraw.

When the 4 trains first start the player spawns in these invisible brushes, which are parented to train 1.
When the trains stop the player is released.

This method won’t work very well in a multiplayer game, unless you use a series of triggers and get the timing right, so the player can be locked in the train.

I’m still trying to come up with a better method of locking the player in trains like these.
The only reason the player even needs to be locked in is the angle of climb and decent used in this tutorial, which will no doubt be the case if you create a Roller Coaster for HL2.

Here are the actions taken when the map spawns:
1) Player spawns in Train 1 and is enclosed in an invisible set of func_brush.
The important settings for these brushes:
Name: PlayerLock (6 func_brush all with the same name.)
Parent: Train01 (They will move with the train.)
Disable Receiving Shadows: Yes
Start Disabled: No
Disable Shadows: Yes
Solidity: Toggle
Solid BSP: No

Flags: Ignore Player USE; Checked
2) logic_auto starts each of the 4 trains forward.
Flag: Remove on Fire; Checked


Notice that the Target Input is SetSpeedReal, this is the same each time I change the speed of these trains.
3) As the trains get to certain parts of the track I’m using SetSpeedReal to gradually speed the trains up, as one, and then slow them back down before stopping.


4) When the trains get to the incline I’m using a path_track to play clicking sounds, from an ambient_generic. (For the effect of a Roller Coaster climbing)
The Sound I used is ambient/machines/keyboard4_clicks.wav


5) When the trains complete their journey one of the last path_track’s will slow them down, stop them and release the player.


6) All 4 trains share the same exact settings, except for their name and the name of their First Stop Target.

Class: func_tracktrain
Name: Train01, Train02, Train03 and Train04
Disable Receiving Shadows: Yes
Disable Shadows: Yes (To save on system resources)
First Stop Target: Track2, Track1, Track0 and Track17
Maximum Speed: 260
Initial Speed: 0
Change Velocity: Instantaneously
Change Angles: Near path_tracks
Distance Between the Wheels: 50
Height above Track: 20
Bank angle on turns: -10 (Roller Coaster effect)
Damage on Crush: 0
Move Sound: ambient/machines/train_wheels_loop1.wav (Train01 only)
Start Sound: plats/train_use1.wav (Train01 only)
Stop Sound: plats/ttrain_brake1.wav (Train01 only)

Flags: (All 4 trains)
No User Control; Checked
HL1 Train; Checked
Is unblockable by Player; Checked

There’s a lot more you can do with this effect.
I’ve included much more in the project file than is mentioned in this tutorial.

I’m hoping I’ve included enough to get you up and running.
Please forgive the track I made for this one, to create an actual coaster set of rails would have taken a lot of time, but I’m sure you’re going to create an awesome set of rails anyway.

Here are some shots from the game:




Alyx is only meant to be a side-show in this project, simply for fun.
Here's a thought; Imagine if the ropes were gone and the plank was invisible.
It would look like the NPC (Alyx) was floating in mid air.
(This includes the Hostage I put in the CS:S version for this project.)


There’s a lot more you can do, I hope I’ve stimulated your imagination.
  The example used in this tutorial.