Would it be possible to add a warp/distortion effect when aliens teleport in?


Many years back - long before the first mod release - I suggested that when aliens appear, as well as having just a zap of green electricity, there could be a ‘warp’ effect, to create the impression of a spacetime rift opening. Similar to the distortion effect when a Strider charges its big energy cannon in Half-Life 2. Also, in HL2 Episode 2, when the the anti-Strider bombs are teleported to you, Valve had the teleportation effect be a similar sort of black hole distortion.

At the time, I think the idea was dismissed as being potentially too graphics intensive, that a distortion effect during action scenes with explosions could cause a big framerate hit. Especially if lots of aliens teleported in. (This was back in 2009 or something, heh.) Personally, I never thought that was likely to be a problem, games like FEAR had done distortion warp effects every time a grenade or barrel exploded.

Recently, the in-development Source mod ‘Peer Review’ was announced - a Source engine remake of Half-Life Decay - and their first video shows that they’ve implemented a distortion effect whenever an alien teleports in. It’s quick and brief and subtle, but it looks pretty cool. I’ve linked to a moment a few seconds before some aliens teleport in. (There’s plenty of similar moments before and after as well.)

When I saw that video, I immediately thought ‘Now THAT’S what I’m talking about! After all these years, someone has finally done it!’

Also, the latest video from the developers of Operation Black Mesa / Guard Duty (the in-progress remakes of Opposing Force and Blue Shift) shows that they’ve implemented distortion effects for the muzzleflash of every gun. Maybe that’s a bit excessive, but it illustrates my point. Nowadays, in 2019, distortion-effects can be easily handled by gaming PCs, they aren’t going to cause big framerate hits.

Back in 1998, the best Valve could do was a green explosion sprite and some green electricity. But things have moved on since them, I think Black Mesa could do much better, without ruining the Half-Life feel.

The ‘Peer Review’ mod has already demonstrated that it looks good asthetically, and it still resembles the classic Half-Life teleport effect, the distortion is simply an enhancement. It also makes sense thematically. The resonance cascade causes a ‘dimensional breach’, Marc Laidlaw’s Half-Life story synopsis talked of ‘spacetime shattering’ and ‘rifts’ opening everywhere. And Valve themselves did a warp effect for teleportation in HL2 Episode Two. So rather than just a green flash and electricity, lets see some space warps!


Hi, I’m the developer from PSR who made that particle effect - I’m glad you liked it!

I feel I should point out that Black Mesa’s equivalent of the teleport effects does have a refraction layer, however - I know this because in the process of making our warpball I took a peek at theirs to figure out how portions of it worked. (I am not an experienced particle artist, and it took some work to get those lightning bolts behaving properly ingame!)

The difference between my rendition of the warpball and Crowbar Collective’s is mainly on how the refraction is utilized; Theirs is very subtle, mine is exaggerated, (A refraction value of -0.175 compared to my -0.25, much larger particle scale, and mine uses a more ‘severe’ normal map) and additionally where my effect is more of a “cone” theirs is more of a splatter:

In the end I think it comes down to priorities; Crowbar Collective wanted to emphasize the green lightning, we at PSR decided the refraction should be the star. Neither direction is “correct”, just different ways of creating the same effect.

Hopefully we’ll figure out how to do the muzzleflash distortions - making refraction in the air as opposed to as a surface look decent in Source without cutting down the framerate or causing sorting issues can be a challenge - Even on modern PCs alpha sorting is hard!


To be honest, the first time I watched the video you linked, I didn’t even pay attention to the distorsion effect. I had to watch it a few times to realise “oh right, that’s what he was talking about”. Therefore, I’m wondering if it would be worth the effort, because it’s not so noticeable at first glance, at least in my opinion.
But if Crowbar Collective (or a modder) is willing to do it, I won’t fight the idea :wink:


Aha! I never noticed the distortion effect on Black Mesa’s alien teleport, as you say it is much more subtle. (And yours is a cone/funnel, which is a more traditional black hole/wormhole effect, while Black Mesa’s is literally a water splash.)

Also, perhaps this means that I could mod the game myself by replacing the current vtf file with a more powerful distortion effect simply by replacing the vtf normal file. I might try grabbing the Strider cannon’s distortion effect and plonking that in there, see what that looks like. I shall do a bit of experimentation tomorrow!

Oh… unless Black Mesa’s teleport re-uses an existing wasterplash effect that is actually used for water splashing. That would mean any time anything splashed in water it would look like a black hole vortex just opened up… hmm.