I have recently been following this awesome talk by Eben Cook on this threshold animation for the blood effects he did in The Last of Us. I have followed it up to the point he talks about generating the normals but after that i am a little unsure of exactly whats going on. He generated a base normal from the threshold map with crazy bump. He is also generated some sort of gradient map based on the threshold and combining the gradient map with the normals in some way to get the final result.
Can anyone elaborate more on what exactly the shader is doing? The functions and math steps that are going on to combine the base normal with the gradients in order to get the final result.
Also, what is the purpose to having multiple colors in the gradient map? Is the gradient texture being generated on the fly by the shader or is it something that is authored by the artist?
Lastly, is the “final” normal being generated by the shader, or is all this an offline process that is authored by the artist? He did mention that they do the blending in the shader, but im unsure as to exactly what he means. (type of blending?)
Any insight would be greatly appreciated!
P.S. Here is the gdc talk im referring to. Thanks to Eben Cook for sharing this awesome technique!