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The first part of the article about describing sphere rotations with a direction and magnitude has some overlap with quaternion rotations, described and visuali
by nayuki 5y ago
The first part of the article about describing sphere rotations with a direction and magnitude has some overlap with quaternion rotations, described and visualized nicely here: https://eater.net/quaternions/ https://eater.net/quaternions/ ; https://www.youtube.com/watch?v=d4EgbgTm0Bg https://www.youtube.com/watch?v=d4EgbgTm0Bg
The second part of the article about untangling strings after a 720° turn is also covered in: https://www.youtube.com/watch?v=JaIR-cWk_-o https://www.youtube.com/watch?v=JaIR-cWk_-o ; https://www.youtube.com/watch?v=Nat-EsReXtQ https://www.youtube.com/watch?v=Nat-EsReXtQ ; https://www.youtube.com/watch?v=O7wvWJ3-t44 https://www.youtube.com/watch?v=O7wvWJ3-t44 ; https://www.youtube.com/watch?v=Rzt_byhgujg https://www.youtube.com/watch?v=Rzt_byhgujg
- deleted 5y ago[deleted]
- deleted 5y ago[deleted]
- phkahler 5y ago>> The first part of the article about describing sphere rotations with a direction and magnitude has some overlap with quaternion rotations Some? Scale the direction vector (x,y,z) to have magnitude = sin(theta) and then set w = cos theta, where theta is half the desired rotation angle. Then (w,x,y,z) is the quaternion that represents the rotation. It was hard for me to read without that relationship constantly popping into my head.