Explorable videos: Quaternions and 3d rotation

Following the last video, this project gets into how quaternions apply to 3d rotation. This is introduced with a short video on YouTube, but things get much more interesting after that...

The bulk of this lesson is actually hosted off YouTube, where thanks to the fantastic web development wizardly of Ben Eater it is done in the form of "explorable videos" that you can interact with during the narration. To accommodate anyone landing on the page of explorable videos without having watched the ~36 minutes of YouTube content above, some of the explorables are a bit redundant with the previous video. But a little repetition never hurts when we're dealing with a difficult topic.