We usually write about what we learn,
so hopefully you can learn too!
With the continuous rising popularity of VRChat and its standardisation as a virtual meeting point, Polygonal Mind contributed to its growth by creating 100 avatars available in the platform. This took the team to think about a "room" in the virtual world of VRChat where you could hang out with friends and change your avatar to one of our creations.
Background of the issue
Creating a visually impressive scenario need the use of a high dose of creativity. And so Laura Uson lead the visual development of the scene, taking the impressionist painter Gauguin as the main inspiration for our environment. The vivid colors of the paintings and the simplicity of the shape direction and vague definition is one of the main highlights of our environment.
In this project I took the lead in general composition and technical development, this meant to be in charge of all the optimisation and general look alike by compositing and creating a good looking environment by level design, lighting and colour harmony. And one of those tasks to perform was to have a water flowing among all the static-ish environment.
To do so we heavily relied on Seamless textures getting animated to simulate water flowing.
#01 - Seamless textures can create flowing rivers
It is true that seamless textures are a great way to achieve massive texture distribution without feeling that there is some kind of repetition grid and everything looks overall uniform. This type of textures also work great to make flowing rivers or fluid movement. Said so make shape direction your main ally for flow movements, think about a "starting quad" and an "ending quad" where water will flow along the loop.
The 3D quad adaptation to an square texture also gives you the ability to shape the “stress” of the water flow by enlarging or stretching its area in the UV space. If you stretch the quad in the UV space you will get a quicker and stressed water flow. On the other hand if you enlarge its length, you will get a calm and slower flow of the water path.
This technique can be applied to a wide range of standard water flows like broken pipes or waterfalls.
In order to achieve this, we created a seamless square texture along the Y/V axis so the river would follow this pattern vertically, and so the animation goes from a Texture tile offset from 0 to 1 during X time. This way your "simple trick" animation will be always flowing seamlessly.
Although in the previous texture tile preview you can notice the "square" repetition due to small details in the texture, this cannot be appreaciated in the river mesh, as its quads only match the X/U vertical straight boundaries, while the horizontal edges mantain an unfolded freedom. This makes the texture to not necessarily match the whole square as its texel density is uniform along all the mesh. Of course this was our desired approach, you can always match the full square for different visual appealing results.
#02 - Seamless textures can create flowing oceans
The river came firstly, as its a simple UV animation logically made and thought, but we faced that the ocean couldn't be animated the same way as its flow doesn't behave the same way. The main issue was to "imitate" and do a visual ressemble of the ocean waves in a calmed way, without creating wave meshes. The attained look was inspired by the following Gauguin painting:
From the picture from above we can already see how the ocean shape and look a like was made, each "wave" was made by creating a river that went along the shore to the limits of the map, creating a water flow that ressembled to the sea.
At this point you can already guess that you cannot animate it the same way as it is animated the river, in this case the animated axis is the X/U axis, moving the foam closer to the shore.
This could be achieved by doing a seamless connection between all the faces, this time each quad occupies the whole UV region, creating a seamless mesh deformed by its own mesh. The stress points now are made when there are more (and smaller) polygons instead of smaller UVs.
And that's all about the project breakdown regarding this particular environment effect and animation. The next two points are going to be focused on creating this effect step by step.
#P1 - Ok I made a river, How do I create proper UVs?
Once you have the initial River mesh you will probably have a UV mess. Because how Maya behaves, UVs get deformed as the Maya engine performs the commanded operations. My recommendation is to delete all the UVs and select the path loop the river will follow, you should get something like this by using a contour stretch:
As you can see, with the Maya History deleted and the shape Frozen, an one-opened loop will be displayed like this when performing a Contour Stretch. You can say that it still doesn't look right (because the whole mesh has been stretched to the coordinates 0,1 in the UV axis) but it has the water flow direction already. From this point the best forward step to do is to scale in the V axis the whole UV shell until finiding the desired texture stretching.
Remember rotate the sheel and align the last quad of the river as the highest point in the UV coordinates, this way the animation value towards a positive axis will get displayed properly. Otherwise the river would be climbing up the waterfall.
With the UV length expanded along the V axis you now have a proper seamless water flow in a river, good job! Now let's take a look to the next point.
#P2 - Now I want it to flow, Animation.
One of the many benefits of Unity is its simplicity when it comes to animation. Unity is an engine capable of animating through its animation engine almost any public property or value displayed in the inspector of a gameObject in scene. All you need is to create an Animation Controller in one of your Assets folder, create a default State and create an Animation clip assigned to it.
Once you have done this, you can start to create and edit your water animation in the Animation Window (CTRL+6).
With all these Unity basics you will have a beautiful (and maybe simple but effective) water flow. From this point everything is ad-on and there are infinite ways to keep experimenting and improving this workflow, it will always depend on the artistic and visual approach you are trying to get.
With all the things said, I will pack my tools and do my last paragraph as a farewell. This was my very first time doing a river flowing, sea waves approaching and a waterflow being alive, but I have been already experimenting with texture offsets for a wide range of other applications. Because it's more important to know the useful basics and tech tricks instead of very particular cases of technology and graphics applications. Experimentation is key in this world!
That's all you need to start experimenting with simple water flows, there is no real need to use Particle Systems or complex Shaders, with the correct texture and clever usage of UVs you can achieve amazing results that at the same time will do a less impact in performance.
You are more than welcome to drop any question or your try-out and results!
I purr when you're not looking. I'm passionate about environments and all the techie stuff to make them look rad. Learning and improving everyday to be a better hooman.