Sgt. Conker We are "absolutely fine"

Article : Realistic Soft Edged Water In XNA

That’s it! Enjoy your new awesome planar water, all in shader 2.0!

Performance Considerations

While this sample doesn’t go out of it’s way to slow things down, it isn’t exactly optimal. There are some thigns you could do to potentially speed things up. The biggest overhead for most people in a game situtation would be having to render the scene 4 times. Currrently we render scene depth, scene color, and water reflection to render targets, in 3 separate sets of draw calls, prior to a fourth set of draw calls to the backbuffer. Fotunately, we can reduce those first 2 sets of draw calls to just a single set using MRT (Multiple Render Targets). This would mean that each shader rendering a scene element would also have to render its linear view depth to one of the render targets, as well as its color, so a custom shader would be in order.

Without MRT, the depth target could possibly use a half precision float, or perhaps packed integer format to save memory and speed things up. I have found that it is rather hard to keep acceptable precision for the shoreline though.

Another way to speed things up would be to reduce the size of the reflection render target, if lower resolution reflection was acceptable.

The water shader itself could also have some more microoptimizations, moving a few calculations to the vertex shader since there are a few more TEXCOORD registers available to interpolate results along. You would probably want to do this anyway if you are pixel shade limited.

Taking it Further

What if you want to do more? Sure, there are plenty more things you could do. The first and most obvious one would be to enable rendering underneath the water. When the camera Y position is less than the water plane Y position you would need to flip the cullmode to draw the back of the plane.In such a scenario the shader could do without reflection, depth colors and shoreline blending. In addition to a modifer water a shader, you would probably want a post process shader to shade things blue (or whatever your deep color was) as well as add a ripple effect.

There are more things you could do with the shader, although doing so would likely push it to shader 3.0. First is taking multiple refraction samples around the current offset pixel and averaging them to perform a box blur. You could also use a second normal map at a different scroll speed, perhaps going in the opposite direction. Such a normal map would be best if subtle, or complements the original normal map.

Download the sample: Here

About CorporalX

Professional XNA/.NET developer.