Korn Shell Ray Tracer


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You can also use your local clone with git send-email.


The Korn shell RayTracer


  1. Synopsis
  2. Install
  3. Tests
  4. Contributing
  5. License


krt [-s sqrt] [-n nearest]

krt is the beginning of a raytracer written in pure shell. There is actually nothing particularly korny about it, this is just a reference to my other project kbf. It is currently compatible with ksh and bash, and probably with any shell implementing the local keyword.

The option -s allows to select among three algorithms to calculate the square root of a given number: heron, newton and bakhshali. All three are implemented in sqrt.sh. The default algorithm is newton and was picked at random.

The option -n allows to select two methods of finding the nearest approximation of square root: dynamic and fixed. The first method, dynamic, is extremely slow and should not be used. The second, fixed, is the default but required a pre-generated list of squares named perfect_squares.txt.

Such a list can be generated beforehand using this helper script:

$ perfect_squares.sh > perfect_squares.txt

For now there are no scene, no floor, no lights, just a hanging red sphere on a blue background. This is the same as section 5 of Ray Tracing in One Weekend.

Here it is:

Blue background and red sphere

It took my laptop 47 minutes to generate it.



  • Any a-bit-more-than-POSIX shell.


There is a makefile available, just run make. Note that there are no install rule.


Either send send GitHub pull requests or send patches on SourceHut.


All the code is licensed under the ISC License.