Vacuum Tube

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The Vacuum Tube (or Vac-tube) is used within the Aperture Science facility in the bts (Behind the scenes) areas of Portal, to transport testing apparatus (aka. cubes, people, etc.). The vacuum tube was picked because it shows that Aperture only choose the most ridiculous way to transport material objects.

How to create one

First, start off making the basic shape by combining these models, make them twisty, make them windy, end them behind a wall, or going into a wall. Here is a list of useful models: vacuum_entrance_a.mdl vacuum_flange_a.mdl vactube_connector.mdl

Making items inside

First, start by making path_tracks. Don't forget to turn on 'Teleport to this path' in the first 'path_track'.
Now create 2 prop_dynamic_overrides, and 3 brushes in the same place. Convert two of them to func_rotating and the 3rd one to func_tracktrain.
Parent prop_dynamic to func_rotating, func_rotating to 2nd func_rotating, and then to func_rotating. Set track train speed to 450-600, height above track to 0 and distance between the wheels to 0.
Now go to flags and check Allow Roll (Z-rot). Now open both of func_rotating and in flags check "X Axis" in the first and "Y Axis" in 2nd. Set rotating speed to 150.

Now set 2 different models to prop_dynamics_overrides. Create logic_auto and give it outputs.

	My Output	Target Entity	Target Input	Parameter	Delay	Only Once
	OnMapSpawn	prop_dynamic_override1	TurnOff		0.00	No
	OnMapSpawn	prop_dynamic_override2	TurnOff		0.00	No

Create logic_case and add output:

	My Output	Target Entity	Target Input	Parameter	Delay	Only Once
	OnCase1	prop_dynamic_override1	TurnOn		0.00	No
	OnCase1	prop_dynamic_override2	TurnOff		0.00	No
	OnCase2	prop_dynamic_override1	TurnOff		0.00	No
	OnCase2	prop_dynamic_override2	TurnOn		0.00	No

Now in the last path_track of your tube create outputs:

	My Output	Target Entity	Target Input	Parameter	Delay	Only Once
	OnPass	(Your logic case entity name)	PickRandom		0.00	No

Gels

To make gel flow through tubes create an info_particle_system. Then set the particle to one of the following gels:

1. blob_curve_orange - Propulsion Gel
2. blob_curve_blue - Repulsion Gel
3. blob_curve - Conversion Gel

Then create an info_target entity, name it, check the "Always transmit to client (ignore PVS)" flag and set the info_target as control point 1 of the info_particle_system you created before. The Gel will now go straight from the info_particle_system to the info_target.

The distance between those two entities will determine how thick the gel flow is.