Water shader study

 Here is a study of a water shader that I created a little while ago. The shader is based on a simple idea of using a black and white height map and a normal map that defines the heightmap where the water will be and how the normals are oriented.

Download the project file here.


See the screenshot of the shader network inside the Phenomenon. Many parts could be wrapped into Phenomena themselves, but I leave that to the users as a practice.

This is a preview of the water shader network inside the Phenomenon. I broke up the network into sections (though some functionalities overlap, but I tried to give it a rough structure. See the  (Note that in the image one node does not belong to any section. This is because it does nothing, and I removed it from the final .xmsl that you can download from the mental mill blog)

How the effect is created (a rough overview)

Two different procedural perlin noises are combined to a float2 that is biased around 0 so that the values vary between -1 and 1. These values are used for

• texture coordinate distortion (for the fake-refraction texture lookup)
• caustic generation
• water normal generation

A height map and a normal map that are both derived from the same source are used. The height map is used to calculate the water-falloff and the normal map provides the normal of the shape that 'contains' the water which is used for the diffuse shading.
The height information is used to create the falloff of the water (when it fades to the water color). Caustics are generated by using a special shader that is fed by the procedural float2 value.

All effects are finally combined and composited: Reflection, (fake) refraction, water color, caustics to generate the final look of the surface.

What to improve
The next things that would be interesting to do is, to find a way to replace the procedural waves with some cheaper normal textures that would save a massive number of instructions. However, this would raise the question how the caustics are generated, since this is done in a special shader.