Timeline for Understanding how to use Quaternion to rotate object
Current License: CC BY-SA 4.0
11 events
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| Jan 22, 2024 at 21:03 | comment | added | KdotJPG | It may also be useful to look into rotors / multivectors / outer products from geometric algebra. Quaternions are actually just the 3D case of rotors with different (and perhaps less clear) naming conventions. Article/video: marctenbosch.com/quaternions | |
| S Jan 22, 2024 at 17:29 | history | suggested | CommunityBot | CC BY-SA 4.0 | Conjugate notation is * |
| Jan 21, 2024 at 15:38 | review | Suggested edits | |||
| S Jan 22, 2024 at 17:29 | |||||
| Feb 5, 2021 at 16:10 | history | edited | PentaKon | CC BY-SA 4.0 | add omission about unit quaternion |
| Feb 4, 2021 at 14:24 | comment | added | PentaKon | The behavior you describe is correct. The rotation axis [0,1,0] is essentially the y axis of your 3D coordinate system, not the cube's y axis! Which is why the cube moves. It rotates around the "coordinate system y" if you will. In order to rotate around itself, mathematically what you do is first apply a translation transformation to the cube and move its center to [0,0,0] then rotate it around y as normal then apply a second translation to move it back to [0,0,-5]. | |
| Feb 4, 2021 at 11:42 | comment | added | Filip Cacic | I m so sorry, i reall appreciate the help, but I just cant seem to understand, I guess I m missing lot of fundementals. Let say I have a cube that is in position [0,0,-5] and want to rotate it by 45 degrees? What I did at first was, axis quaternion =[cos(45/2),0,1,0], I wanted to rotate around y axis. I multiplied that qutaernion with position[0,0,-5] and with conjugate. Result was object was completely moved from its origin. Now I cant understand If make my quaternion axis equals [0,0,-5], how is that going to rotate him on y-axis | |
| Feb 4, 2021 at 8:41 | comment | added | PentaKon | The object rotates around an axis which is represented as a vector. That vector starts from (0,0,0) and points to (x,y,z). If you want the object to rotate around itself, the axis vector should then start from (0,0,0) as all vectors do and point to coordinates (x,y,z) that correspond to the object's center. You decide where exactly in your object that is and it depends on its position in the 3D space. For example if you have a sphere with its center at (1,1,1) then your rotation axis would be the vector [1,1,1]. | |
| Feb 3, 2021 at 23:43 | comment | added | Filip Cacic | Just one more question, when I use it like that, my object rotates around some imaginary center, it does not rotate around itself, meaning he is not staying on the same position. | |
| Feb 3, 2021 at 23:03 | comment | added | Filip Cacic | Dont know what to say, amazing, thank you so much for dumbing it down and explaining it so clearly. | |
| Feb 3, 2021 at 23:02 | vote | accept | Filip Cacic | ||
| Feb 1, 2021 at 14:28 | history | answered | PentaKon | CC BY-SA 4.0 |