Ocean Simulation

I love games which can change the entire mechanics of its self by creating a world that is something different. This is what the Mario Galaxy games did by creating planetary bodies to open up a variety of new mechanics that otherwise would not have been available. And this is also something Assassins Creed Black Flag did with its ocean, creating a non-static world that was something I had never experienced before. It was a world with a personality, that could work with or against you.

Ever since I played the game I wanted to figure out how there ocean worked and create it. Lucky for me I came across an article that interviews an Ubisoft employee who explains how the ocean works entirely (Assassins Creed Tech Article).

One of the first thing I wanted to get right before anything else was getting the waves procedurally animating on a plane. With a series of values that I could adjust to change the size, speed, or shape of waves. Before I could do any of this I had to study into Gerstner waves. A Gerstner wave is a wave that forms peaks and troughs. And the collective Gerstner waves is a summation of multiple individual Gerstner waves of different amplitudes and wave lengths to form a fractal implementation.

I decided to work with the Unreal Engine, because I enjoy working with its Blueprint system for creating shaders. The implementation of Gerstner waves into a shader also went rather well with the use of this GPU gems chapter of water simulation (GPU Gems Water simulation Article). Helpful laying out all the equations I need to implement this functionality. Though I came across an annoying issue that I have never seen before. For some reason Unreal Engine shaders do not use radians or degrees. Instead they use a normalised value between 0 and 1. So 2pi (Radians) = 360 (degrees) = 1 (Unreal). I do not understand why it does this, but it took a long time to debug.

I managed to get the shader set up, and a manager that could send down values to the shader in order to control the shape, speed, or size of the waves being created. The end result was very effective, and am quite happy with this first step.

 

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