Grand Theft Auto V has some nice fountains which I would like to present you – but sometimes it’s a bit hard to admire them in the game :,(
It can be equally hard to put nice water effects into a game. One reason for this is, that water has an always-changing surface-topology.
While the polycount for e.g. a cloth-simulation stays consistent (and the vertices “just” need to be moved around) every frame of a water-simulation has a different amount of polygons/vertices:
It’s possible to use newer techniques like Vertex Animation Textures or “Geometry Flipbooks” á la Alembic but what I saw in GTA was simpler – that’s why I would like to show it to you.
Here is the first one. As it looks a bit like a worm, let’s call it:
In case you think: “Well … that’s water, so what?” I would like to underline, that having a nice volume and/or silhouette for the water is not that easy – and in the example above we have a both! <3 :)
To illustrate the problem: For water-effects often a water-texture is moved along a flat surface which sometimes works very well. Here, is a great example which we shall name:
Wedding Cake Fountain
But if try to mimic the “Wormy Fountain” by running a texture along a static geometry (like it was done for the “Wedding Cake Fountain”), the trick gets very obvious when looking at it from the side:
Of course, you could use a geometry with some volume instead of a flat plane. Luckily, GTA offers an example for that as well. I’m introducing to you – last but not least:
Here we have a geometry which some volume which works perfectly fine from any angle but there is a “but”.
Here comes the “but”.
But the silhouette is very static and not as dynamic as we saw it on the “Wormy Fountain”. Let’s look at the effect again:
Looks very good from all angles and has a nice dynamic silhouette, doesn’t it?
The secret behind this water-stream is called: Spline with camera-facing quads.
The polygon-ribbon is re-orienting itself toward the camera and with that you’ll never see, that it’s actually a flat polygon-stripe. Only when you look at it from very extreme angles, you might see some artifacts:
You may have seen similar techniques in other areas for example on the Home World Trails or from the Company of Heroes flame thrower (see image below), but I thought making a fountain with that is very creative so I had to share it with you guys. :)
By the way #1
Here is the texture which was used in GTA:
By the way #2
I have no idea what these smaller geometries are for … they are not visible in the game:
By the way #3
This effect inspired me (together with other influences like this great talk about loopable liquids in Mortal Kombat – careful, the talk also features many blood effects!) an idea in my mind: If a simple moving texture on a polygon-trail/spline already looks so nice, could this work even better with a tileable mesh moving along a spline?
To test this, I made a small side-project:
It uses two tileable meshes (generated in Houdini) and 5 instances of each run along a spline. If you want to see the full breakdown, I put everything together on my Artstation post.
Thanks for reading my article. <3
I hope you’ll like it!
And never forget: