@@ -144,7 +145,50 @@ Grin material with coordinate system tilted against global coordinate system.
Water droplet which bends the light of different wavelengths differently in order to create a rainbow.
The material data was obtained from https://refractiveindex.info by Mikhail N. Polyanskiy.
## Formulas
# Frequently Asked Questions
## I know of another raytracer project, why not combining forces?
Our goal is to provide a very general raytracer with arbitrary coordinate systems and nearly arbitrary materials and we want to see how far we could go this route.
This implies also some conceptual problems on the road which are difficult to solve and therefore our development is far slower than it could be.
This also implies that we cannot properly throw together code with projects where the goal is "to just get this
raytracer done and useable". At the end of the day our raytracer should also be useful, but maybe our goal is not compatible with other raytracer projects.
Nevertheless: we are always interested in contributions, questions, issues and if somebody implemented cool stuff or is interested in our stuff, we are happy to provide interfaces or code.
https://github.com/mess42/pyrate/issues/142
## What about the FreeCAD interface?
The FreeCAD interface has more or less the status of a mockup and is broken since the last large refactoring in 2017. Until now there is no good idea about getting a not-so-tight coupling between FreeCAD classes and pyrate classes. Since the API is not quite settled it is really difficult to start with a full fledged FreeCAD interface without rewriting all the stuff when there is a slight API change appearing. All ideas here are appreciated. If you are interested in digging into the matter, please have a look in the `freecad/PyrateWorkbench` directory.
https://github.com/mess42/pyrate/issues/136
https://github.com/mess42/pyrate/issues/134
https://github.com/mess42/pyrate/issues/91
## How does the optimizer work?
The optimizer decomposes in backend and frontend whereas the backend determines which optimization algorithm is used and the frontend determines which meritfunction or parameters to be used.
There were several discussions on that in the following issues:
https://github.com/mess42/pyrate/issues/140
https://github.com/mess42/pyrate/issues/137
## How to create a full sphere lens?
Since the `Conic` surface solves the ray intersection equation analytically and the two intersection points in a sphere correspond to the two roots of the quadratic equation, one cannot properly use two subsequent `Conic`s and expect a proper raytracing. In issue XX and our own research, we came up with a few workarounds:
* use a slightly deformed second surface (introduce radius deviation or slight conic const) -> this is no optimal solution when you need an exact sphere
* use the `Asphere` type surface to avoid the quadratic analytical solution problem and use a numerical solver instead
* use an intermediate plano surface (this is the most reliable solution without any downsides)
https://github.com/mess42/pyrate/issues/149
https://github.com/mess42/pyrate/issues/50
# Formulas
If you want to use formulas in issues or wikis, then the following example would be useful:
