Thought of You. BioMotionLab. Dance with Hands. Hallucination. Drop in slow motion. The Basics of Video Editing Part III: Effects and Color Correction. Animating Water. Last week I attended SIGGRAPH 2010, and among the many good presentations, Valve game a talk on the simple water shader they implemented for Left For Dead 2 and Portal 2. So on the plane ride back from LA, I whipped up this little sample from what I could remember of the talk. Edit: You can find the talk here: The standard technique for animated water is scrolling normal maps, as I’ve previously written about. The problem with this is that it looks unnatural as water does not uniformly move in one direction.
The Flow Map First we need to create a flow map. Using The Flow Map Now we need to use the flow map to alter the water normal maps. The graph illustrates that during a cycle time from 0 to 1, we want the layer to be fully interpolated at the mid-point in the cycle, and fully un-interpolated at 0 and 1. In the code above, HalfCycle would be .5 if our cycle was from 0 to 1. And that’s pretty much it.