These are my first stab at creating NPR shaders in cycles for line and cross hatching using only procedural textures. I'm fairly happy with this as a start, though there are a few things I still want to add, including:
<ul><li>Variable line width - the current shader gets tonal range from adjusting the color of the line. This is somewhat limiting, and to get a full range of tones, I need to add the ability to adjust thickness based on tonal value</li>
<li>Support for cast shadows - Currently, the tonal value comes from the diffuse and specular lighting only - shadows cast from other objects do not affect the tone.</li>
</ul>Despite those shortcomings, I can still see uses for the shader in its current form, so I thought I'd share.