Improve shading to properly display blind holes

[hannobraun]

Problem

This is how blind holes currently look:

You can reproduce this picture, by running cargo run -p holes from the repository root, then rotating (drag while left mouse button is pressed) and moving (drag while right mouse button is pressed) the model until you see the blind hole.

As you can see in this screenshot, the surface of the part and the bottom of the blind hole look exactly the same. This is because they are parallel, and the shading only depends on the angle between a surface and the viewing direction.

Solution

I'm not an expert on graphics, and I'm sure there are many ways to improve this. If you know of one, feel free to implement it!

The solution that comes to my mind, is to make shading also depend on the distance to the camera. This would have to be carefully tuned, to make cases as the one shown in the screenshot look decent, without making far-away parts completely black. It might make sense to clamp the result in such a way, that the effect of distance can never make a part too dark.

Implementation

Rendering is implemented in the fj-viewer crate, specifically within shader.wgsl. It's possible that this issue can be completely addressed with only changes to the linked shader function. It's also possible (especially, if a more advanced solution is chosen), that this requires changes to the larger graphics system.

In any case, implementing this will only require knowledge shader languages (I'm guessing that WGSL is pretty easy to understand for anyone familiar with other shader languages), and possibly Rust and wgpu. It won't require knowledge of other Fornjot internals. For this reason, I'm tagging this as a good first issue Good for newcomers .