Three Dollar Quill

I wanted to have some kind of a buffer before posting things, but I'm at an impasse here and it's annoying me, so I'm going to vent. First off, the whole idea of "anaglyph sketching". In the past, I've tried to work through Drawabox, before getting distracted or whatever, and one thing I remembered was that for the perspective stuff, my understanding of the goal was to drill on making stuff "look 3D". What recently occurred to me was, it's all lines with no hue information; that means that, in theory, sketches and stuff like practice outlines could be done in red and cyan, and the degree to which it appears 3D could be objectively assessed with the use of anaglyph glasses.

From my initial experiments with one of the art apps on my phone, I can confirm that sketching an anaglyph line is possible, but I don't have good control over it currently. I concluded that several things are required to get this whole weird idea working:

• Red/cyan images of abstract wireframes, to directly observe and feel the perspective differences from binocular vision.
• Templates in a program like Krita, to set up the required layers for sketching twice.
• Maybe a nicer setup than "it turns out capacitive styluses work on my laptop's touchscreen".

Anyway, here's my current issue. I'm trying to write code to generate the wireframe images from simple data files, and maybe one of my mistakes here is trying to roll my own rendering code instead of just ("just") learning Blender scripting or something, but I'm invested in working out the math now. Now, I'm pretty confident in my ability to do perspective calculations with line segments, as that's basically just doing perspective calculations with points. And that should allow for working with parallelpipeds, or boxes, but I also feel like I should try to generate frames for cones or cylinders, and that is giving me some grief. My understanding is that a circle projects to a conic, but when I try to determine the equation of a projected conic, given an ellipse in three-dimensional space, things break down in ways that surprise me. Either this doesn't actually work, or my pre-rigorous techniques for intuiting how it should work are failing me.

In any case, I've decided that the solution is to try to get an actually good grounding in projective geometry. So, I've got a textbook, and I'll be reading it until hopefully I have a better grasp on how to do some stuff that seems like it should be pretty basic.

Good night.