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<\/a><\/div>\nIndeed, I want a world with various (floating) islands and some waterfalls. Maybe you noticed it, but there is already water in the video game. I previously worked on the main sea <\/a>of the world, and it wasn’t that easy to set up a look that I found OK. I finally chose to have a purely reflective water. The big problem is that displaying the main sea is quite computationally expensive.<\/p>\n If I want to add other water planes (for example a lake on an island) or waterfalls, I can’t use the exact same approach because it will seriously slow down the game. Plus, for a simple plane, computing the reflection is “quite” straight-forward, but for complex shapes (a waterfall), the computations are more difficult and the graphical pipeline of the GPU is not well suited for such a task. So I have to use a work around if I don’t want to spend days developing an incredibly complex material that nobody will notice anyway.<\/p>\n I finally choose a combination of various classical techniques used in video game\/real-time applications…<\/p>\n <\/p>\n An environment map is some kind of “spherical” texture (actually it’s computed from the faces of a cube) that is applied on a mesh according to its normals. The idea is to “fake” the reflection of the environment on the object. <\/p>\n Technically, it is possible to compute such a normal map in real-time to obtain a “true” reflection of the environment. However, as usual, this is quite GPU-heavy (you have to make 6 renders of the scene to create the real-time reflection texture). Furthermore, even with real-time computed reflections, the mapping itselft is still a fake one, which won’t fool the careful viewer’s eye.<\/p>\n Thus, I choose to use a pre-computed environment map: I simply use the cube map of the sky (see this post<\/a> for more details).<\/p>\n <\/p>\n Then, to break the perfect flatness of the water, I add 2 normal maps that moves at 2 different speeds. It creates a nice effect of moving waves. By the way, it’s the same trick that is used to create the waves on the main sea material.<\/p>\n This one is a simple classical moving texture added on top of the moving waves. To keep consistency with the rendering of the main sea, I use pure white for the foam, and I play with the alpha channel to modulate the visual impact.<\/p>\n Because I want the foam not to be straight on this moving water, I add distortion to it by altering the texture coordinates with a noise texture (actually, this is the wave normal map with a different scale and speed).<\/p>\n <\/p>\n <\/p>\n The final difficulty is adjusting all the material parameters of this “fake” water, to match most closely the main sea water. Because the algorithms behind the rendering of these 2 water styles are different, it’s strictly impossible, but I have to minimize the visual gap.<\/p>\nI – Environment(cube) map<\/h3>\n
<\/a><\/div>\nII – Moving normal maps to create waves<\/h3>\n
<\/a><\/div>\nIII – Moving foam texture<\/h3>\n
<\/div>\nIV – Distortion of the foam texture<\/h3>\n
<\/a><\/div>\nV – Day time aware material<\/h3>\n
<\/a><\/div>\n<\/a><\/div>\nVI – Tweaking and particles<\/h3>\n
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