Date of Recording: 2020-10-17
Building a cloud shadowing engine which is consistent with the pixel art aesthetic poses some unique challenges:
1. A purely screenspace approach looks great, but does not behave consistently when the camera perspective changes
2. A purely worldspace approach is stable to camera rotation, but looks artistically inconsistent, and betrays the core 3D engine when the shadows roll over the edge of any object.
The solution is a clever mix of the two approaches, by building a worldspace formulation which assumes the world is a flat relief, and blending it with the physically correct worldspace formulation. The method is similar in spirit to normal smoothing in toon shaders for shading character faces in anime-styled rendering.
The clouds themselves are rendered using a 3D FBM that scrolls in space and evolves over time. After a lot of tweaking, I arrived at a result which I am quite satisfied with. It gives a real liveliness to the test scene.