Gel (Portal 2)

The three main gels: Repulsion, Propulsion, and Conversion on a floor.

Gel or Paint is a puzzle element of Portal 2. It flows out of droppers in blobs, and covers most surfaces or objects it touches, changing the physical properties and coloring it. Gel streams can be redirected with portals and excursion funnels.

Note:Gel works off of lightmaps. This means that a map must have lighting (and not just running VRAD) to render gel splats, and the lightmap scale directly affects the appearance of gel on surfaces.

Bug:Related to the note above, if you are noticing a lag spike when applying gel to surfaces, it's probably because a low lightmap scale is forcing the game to make a more accurate gel mapping. Lightmap scales other than the default 16 may also make gel look more squareish or stretch the border textures.  [todo tested in ?]

There are six gel types:

• Repulsion gel: Blue, and causes things to bounce around.
• Propulsion gel: Orange, and reduces friction, making objects slippery and players move quickly.
• Conversion gel: White, and allows portals to be placed on surfaces that didn't already allow them.
• Cleansing gel: Clear, erases effects of other gels.
• Reflection gel: Unused gel that reflects lasers. Functional, but looks wrong.
• Adhesion gel: Unused gel that made things sticky. Not available in Portal 2, but some modders have remade it.

Note:To fix the reflection gel texture, create a VMT and VTF named "blob_surface_stick". You copy and adapt the information from one of the other texture files in materials\paintblobs\.

Creating a Gel Dropper

Using an instance

1. Place a func_instance entity with the following properties:

Property Name	Value
Fix up Name	gel_dropper
VMF Filename	instances/gameplay/paint_dropper.vmf
$paint_sprayer	gel_sprayer
$trigger_to_start	start
$trigger_to_stop	stop
$paint_type	0 = Bounce, 1 = Reflection , 2 = Speed, 3 = Conversion, 4 = Cleansing

If the dropper doesn't show up, try restarting Hammer.

2. Create the entity you want to activate the gel dropper, such as a trigger_once at the entrance to the room, and give it the following outputs:

	My Output	Target Entity	Target Input	Parameter	Delay	Only Once
	OnTrigger	gel_dropper-start	Trigger		0.00	No

Note:Hammer may warn you that this is invalid. The game will recognize what it is though.

From scratch

1. Place a dropper prop, including any visible pipes.
2. Place an info_paint_sprayer inside the dropper, and tune it to your liking.
3. If there is anything that enables or disables the gel dropper, send Start and/or Stop inputs to the info_paint_sprayer.
4. Depending on your model, you may want to change skins or play animations when enabled or disabled.

If you want to create paint bombs, follow these steps in place of an info_paint_sprayer:

1. Place a prop_paint_bomb, and give it a name like paint_bomb.
2. Place a point_template. Give it a name like paint_bomb_temp and set "Template 01" to paint_bomb.
3. Place an env_entity_maker. Give it a name like paint_bomb_spawner and set "Point_template To Spawn" to paint_bomb_temp.
4. Put this output in your prop_paint_bomb:

	My Output	Target Entity	Target Input	Parameter	Delay	Only Once
	OnExploded	paint_bomb_spawner	ForceSpawn		0.00	No

This how Valve does their droppers in Portal 2. Alternatively, you can use a logic_timer instead using the output above, just change OnExploded to OnTimer. This alternative method will allow multiple paint bombs to be used at once, greatly increasing the chances of two bombs colliding with each other in midair, which can be a simple nuisance, or a clever trick to solve a puzzle.

If your input device can be activated rapidly, consider having a logic_relay do the spawning inputs so that you can temporarily disallow the env_entity_maker from spawning more paint bombs after your device is activated.

Conversion Gel Color

There is some evidence and debate saying that the conversion gel was originally pure white, and that the current gray color was an accident by Valve, made while developing the Art Therapy maps.

How Valve could have missed this is not very clear, because at least one Art Therapy map used conversion gel, so they must have noticed. This gives rise to the thought that it was an intended change, possibly to make it blend in better with darker areas, or so it's more visible on white surfaces.

Whatever the case, you can change it to pure white with this console command: portal_paint_color 255 255 255 255 (requires map restart).

Gel Mobility

Like physics objects, gel can be flung through portals. Like everything else, the velocity of gel is preserved through portals (of course, accounting for the angles of portals). This allows gel to reach areas you may not expect. Careful level design is the best solution. At the potential cost of diminished realism, trigger_paint_cleanser is also an option, and so is %nopaint 1. Below are examples of just how mobile gel, especially conversion gel, can be:

• 

  sp_a3_bomb_flings, the first map where the player can freely place gel. The lower portion of the map isn't very paintable due to few portalable surfaces.

• 

  Inside the test chamber, more surfaces are portalable, enabling more possibilities. Not seen in this picture is gel on the platform the player is currently standing on. With precise movements, the player can use gel to skip the final fling in this test.

Related Entities

• info_paint_sprayer
• paint_sphere
• prop_paint_bomb
• prop_physics_paintable
• trigger_paint_cleanser
• item_paint_power_pickup
• weapon_paintgun
• paint_stream

See Also

• A tutorial on fixing reflection gel.
• Gel-related console commands
• Dropper (Portal 2)