#quaternions

Okay so I have this testing scene for the Beckett Engine, and earlier today I had the idea to try and load camera and light positions from FBX files.

45, 0, and 112 degrees.

Using UFBX to load this, I see a camera node whose local_transform.translation is a vector3 with values [58.19, 63.91, -19.02] which is almost the correct values. Y and Z are switched, and the new Y is inverted. This is probably to be expected — Blender is Z-up but OpenGL(?) is not, it's Y-up.

More importantly, local_transform.rotation is a quaternion but my camera class takes a vector3 of Euler angles.

Handily, there's also the euler_rotation field. That's explicitly called out by the UFBX manual to be in degrees... but its values are [-15.94, -164.64, 47.16], nowhere close to [45, 0, 112].

As a quaternion, local_transform.rotation is [0.17, 0.37, -0.90, -0.07], which is nowhere near what Blender says it should be, [0.517, 0.213, 0.317, 0.765] (both in WXYZ order). And again, I need that converted to Euler angles.

It's a pretty handy feature to have, and a shame if it had to tossed out.

I should note that I did attempt to use these fields, and the results were not at all correct. Ignoring things like Y-up, they were just plain wrong. And manually setting the camera rotation to [0,45,112] does result in a basically correct image.

Or quaternions.

Flowey: Ughhhh!

Flowey: I'm an expert in everything including math, but it just slows down everything unecessarily! Time is wasted with scientific computing and measuring ingredients.

That's why I havent actually cooked for the kid yet.

Flowey: That and... This is a really bad spot to make a cooking fire. But I don't want to move.

...

I've been thinking about non-euclidean geometry for a few hours and now I'm reading about William Rowan Hamilton and the Quaternion things.

I realized I hadn't shared this here yet! Here's my 3D printed Quaternion Julia Set! See I first learned of these things reading about it from a pretty well known graphics programmer Inigo Quilez. Theirs are a lot prettier! But yeah, if you're familiar with Julia Sets and the Mandelbrot set already, this is basically that but we use 4D complex numbers called quaternions instead of the regular old complex numbers.

The original shaders I used to render them were unity CG/HLSL implementations, but this particular one is from a GLSL implementation over on my shadertoy you can find here: https://www.shadertoy.com/view/tdt3W8 It isn't exactly the same one that I've printed here (I've long lost the exact seed) but it is reasonably close. The way I printed it was I stole some marching cube code for blender and just plugged in the SDF function derived by Inigo Quilez, tweaked the values and eventually got a mesh I can print!

This uh, isn't the one I used lol. It did take a few tries to get one that was both visually interesting and also printable. In fact i wasn't even using the marching cube algorithm at first. I was using Poisson Surface Reconstruction with a python script that casted points to form a point cloud. Basically I was attempting to create a mesh like you would with photogrammetry, just with an abstract object rather than an actual thing or place.

The results were, well not good lol.

*Continues digging through box* I know its around here some where, I should have the one that works. Okay this still isnt it but this one is using the same method, I just wanted to use this for a vrchat world instead of using it for 3D printing. It gets the point across lol