added more to the readme

README.md

@@ -1,14 +1,16 @@
 # RayTraceEllipsoid
 
-[![Build status](https://ci.appveyor.com/api/projects/status/voutf74a40lh511f?svg=true)](https://ci.appveyor.com/project/yakir12/raytraceellipsoid-jl)
+[![Build status](https://ci.appveyor.com/api/projects/status/voutf74a40lh511f?svg=true)](https://ci.appveyor.com/project/yakir12/raytraceellipsoid-jl) [![Build Status](https://travis-ci.org/yakir12/RayTraceEllipsoid.jl.svg?branch=master)](https://travis-ci.org/yakir12/RayTraceEllipsoid.jl)
 
-[![Build Status](https://travis-ci.org/yakir12/RayTraceEllipsoid.jl.svg?branch=master)](https://travis-ci.org/yakir12/RayTraceEllipsoid.jl)
+[![Coverage Status](https://coveralls.io/repos/yakir12/RayTraceEllipsoid.jl/badge.svg?branch=master&service=github)](https://coveralls.io/github/yakir12/RayTraceEllipsoid.jl?branch=master) [![codecov.io](http://codecov.io/github/yakir12/RayTraceEllipsoid.jl/coverage.svg?branch=master)](http://codecov.io/github/yakir12/RayTraceEllipsoid.jl?branch=master)
 
-[![Coverage Status](https://coveralls.io/repos/yakir12/RayTraceEllipsoid.jl/badge.svg?branch=master&service=github)](https://coveralls.io/github/yakir12/RayTraceEllipsoid.jl?branch=master)
+This Julia package allows for geometric ray tracing with ellipsoids (actually domes shaped as ellipsoids). It includes intersection and refraction/reflection of rays with arbitrary ellipsoids. It accomplishes that in about 100 lines of code thanks to heavy use of `CoordinateTransformations.jl` and `StaticArrays.jl`.
 
-[![codecov.io](http://codecov.io/github/yakir12/RayTraceEllipsoid.jl/coverage.svg?branch=master)](http://codecov.io/github/yakir12/RayTraceEllipsoid.jl?branch=master)
+These ellipsoid-domes are defined with `Ellipsoid` (see details with `help?> Ellipsoid`). The normal and refractive indices are defined within the `Interface` type. These two are baked into a single `OpticUnit`.
 
-This Julia package allows for geometric ray tracing with ellipsoids (actually domes shaped as ellipsoids). It includes intersection and refraction/reflection of rays with arbitrary ellipsoids. It accomplishes that in about 100 lines of code thanks to heavy use of `CoordinateTransformations.jl` and `StaticArrays.jl`.
+`Ray`s `advance!` to intersect with the `Ellipsoid`s and `bend!` at the `Interface`s. The `raytrace!` function includes these two actions, taking in a `Ray` and an `OpticUnit`, updating the location and direction of the ray.
 
 ## Todo
+- add the `Angles.jl` package to improve how users input cos(α)
 - add rotated ellipsoids
+- add more shapes, so it's not only `RayTrace**Ellipsoid**`