I was disappointed when I found out that the Unity terrain engine did not work properly on mobile devices, so I experimented with a number of different custom solutions. Over time, this project began to evolve into a fractal terrain generator, using simple noise algorithms to produce a randomly generated landscape. Next, I wrote custom shaders to blend between a stony texture and a grassy texture depending on the slope of the terrain. This worked well, but lacked the depth I felt it needed. The final step was implementing the custom shell model used to represent grass. The terrain is rendered multiple times with various vertex offsets in a multi-pass shader, with time and location based fluctuations to emulate wind, and a grass height based on slope, and some user specified parameters.
The system works fairly well, and allows for a simple procedural terrain that can be dropped into any scene.
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- A simple landscape generated by the script.
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- A close-up of the rendered grass, implemented in the base terrain shader.
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- A view of the generated terrain from within the Unity engine.
You can experiment with this script by running the Unity Player here
Andrew Gotow 
Nice work, grass makes me dizzy after a while though.
Agreed! This was one of my first attempts at writing a shader that defined more than shading parameters, and before more complex geometry shaders were possible. I settled with a shell system, but it ended up being a little bit nauseating… 😛
I may re-write this demo later, and I promise I won’t make the grass quite as painful next time!