Watercolor Rendering

Based on this paper I wrote a 2 1/2 dimension water simulator that moved pigment around. I also wrote a paint description shading system that would take input layers from a renderer and transform them, turning them into inputs for the simulation. For example, you render an element in your scene which is a mask. Based on the values of the mask and the watercolor shading description (more water here, more pigment there), you provide the the simulation with a series of inputs, which it runs. The watercolor artistry is in how you translate the render inputs into simulation inputs.

Examples

The first image is the input from the render. Each of the other images is a different watercolor shader that takes that input and does something different. Based on the input, each shader decides how much water, how much pigment, how much drying, and in what order to do them. A single shader can be a long list of simulation instructions.