Business card raytracer / eventual IOCCC winner. See full writeup at https://mzucker.github.io/2016/08/03/miniray.html
To build:
cd /path/to/miniray
mkdir build
cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make
make ppm_images #optional, takes a while
For all versions, you can pipe the output to a PPM image (displayable with ImageMagick display command among other apps):
./miniray > image.ppm
For versions 4.2 and after, you can input your own text:
./miniray "my text" > image.ppm
./miniray "my text" -preview > image.ppm # faster, reflections & AA disabled