Request for new primitives

[Manfred Schaefer]

This is an example of converting the challenging angles to easier angles.
You'd rotate the prim by 45°.

You are correct in that 3 decimals are usually enough for vertex coordinates. In rotation matrices, however, more decimals (up to 6, sometimes even 7 if motivated properly) can be used to maintain reasonable accuracy of the resulting vertices.

I need a circular segment from 22.5° to 45°.
If I understand your explanation correctly, I would end up with a segment from 45° to 67.5°.
This means I would have to reflect a circular segment from 0° to 22.5° across the x-axis and then rotate it by 45° about the y-axis. However, a rotation of 45° implies a factor of 0.707... which results in too many decimal places.

Regards

Manfred