Hi, I finalized the Blender export add-on. 

You can download it from here: https://drive.google.com/file/d/1tGBUr9xX5jzz15eKweNFvm3xB7DlzE_a/view?usp=sharing

Make sure you have Blender version 2.8+ and just install the add-on as normal. (It is very simple and there are tutorials about this if you still can't). Then, you can export your scene from File->Export->Ceng477.

Since there is no ideal conversion from blender scene to our ray tracer scene, I have made some design choices:

    All meshes triangulated and transforms applied (DONT RUN THE ADDON IF YOU DONT HAVE A BACKUP OF YOUR SCENE)
    Support for only point lights, no ambient light support, you can tweak the values in your .xml of course if you really want to have the ambient
    Support for only Principled BSDF materials, since the way blender handle materials very different from the HW so I tried to keep it as simple as possible. Base color stands for diffuse, specular value stands for specular, roughness stands for mirror(but inverse, ie mirror = 1 - roughness), no support for ambient, phong exponent always 1
    Background color taken from World->background color
    Support for multiple cameras but all same resolution
    Important: image_name uses camera name, so name your cameras something like box.ppm
    Camera near plane is 3, I don't know how can I actually calculate this from Blenders camera properties, but this what works for default 50mm camera. If you do know please tell me

These are the main things you should know about the exporter. If I miss something or you experience bug or something please contact me.
Of course what we see in Blender very different from what we see in our renders, so you may need to tweak values of lights, materials for at least a neat look :D