We have liquids in our stomachs and some people like the play around with them. I never understood that. Until i saw the Boomer bile/puke flask in Left 4 Dead 2. It’s a detail (at the characters belt, there is a high quality version of it for holding it in the hand in 1st person view). But, what a detail! It has some kind of physics!
Source: Left 4 Dead 2 Authoring Tools
The solution is “simple” but not less stunning to me. Thanks to Lino (he told me about these L4D2 Authoring Tools) i can bring you good pictures of the investigation.
Here you can see how they did it. They have one bone which reacts the your movement. This bone controls the upper verts of the liquid. The rest is skinned to the second bone. You can see how the cylinder deforms at the side during strong movement.
Source: Left 4 Dead 2 Authoring Tools
I’m happy that the did this “cheap” trick, ignoring that there is some deformation which wouldn’t appear with a real fluid simulation. Because so i could understand it. :)
It would have been totally OK if they would have pre-animated this. Or just do nothing with the liquid inside of the flask. So why I’m so exited?
When i worked on Sacred 2,we tried to make some eyes (growing at the ground, it was a spooky forest) look at you. The idea was to add a bone and let them always point at the player. This never made it into the game. It was too complicated to put this feature into the renderer for the short amount of time we had left. Of course we had other more important things to do that short before the release date.
That’s why I’m always impressed when such details make it into games. Because i know, that (almost) nothing is easy and the most cool things need a lot of time to implement.
Source: Sacred 2 “Ice & Blood”
But on the other side, we made it possible pretty fast to destroy these eyes. Then, a new eyeball spawned but this time with physic. This means you could play football with it. :) This example shows, that sometimes it is easy to implement stuff. (Sorry for the bad performance of the following GIF, my machine isn’t that strong):
Source: Sacred 2 “Ice & Blood”
Valve, you have my great respect! And if you would be a men and i would be a woman, i would like to have a baby with you.
P.s. If you’re interested in the wireframe of the bad boy:
Source: Left 4 Dead 2 Authoring Tools
Update 1
And here’s his Shader-Network. Thanks for sharing Tyler!! :)
Update 2Source: Liquid done by Michael