Create a primitive sampling showcase example

[IQuick143]

Objective

• Show + Visually Test that 3D primitive sampling works
• Make an example that looks nice.

Solution

• Added a sampling_primitives examples which shows all the 3D primitives being sampled, with a firefly aesthetic.

Testing

• cargo run --example sampling_primitives
• Haven't tested WASM.

Changelog

Added

• Added a new example, sampling_primitives, to showcase all the 3D sampleable primitives.

Additional notes:

This example borrowed a bunch of code from the other sampling example, by @mweatherley.

In future updates this example should be updated with new 3D primitives as they become sampleable.

[github-actions]

The generated examples/README.md is out of sync with the example metadata in Cargo.toml or the example readme template. Please run cargo run -p build-templated-pages -- update examples to update it, and commit the file change.

[IQuick143]

Please give suggestions on code quality, visual and performance improvements.

[Jondolf]

Looks good! Might be almost too fancy for just demonstrating sampling, but it does showcase it well and is visually appealing :) A screenshot or video of this would be a great fit for the 0.14 release notes too!

Left just a few non-blocking consistency nits. Also the keyboard inputs for zooming are sort of flipped and/or partially broken like we discussed on Discord, and for example pressing the non-numpad version of the minus/hyphen doesn't work with my Nordic (Finnish) keyboard layout, but I probably wouldn't block over it

[Jondolf]

LGTM! The input issue seems to just be that the physical keys (KeyCode) don't map to the correct logical keys with my keyboard layout, but I don't think we have a good clean approach to do it properly, and the other examples also just use key codes.