Unexpected render for section 2.6 (quad) #1631

Hello,

I am currently working on the section 2.6 (adding quad primitives)
I see that this section is pretty new, so I was wondering if there was a bug of some sort.
The render I produce from the code (which I checked to be the same 4 times) is the following :

It just feels like the scene in not properly setup, orelse it would be a camera issue that I did not spot earlier but this really seems unlikely...

Here is the code I am testing against (branch develop, commit 00588ef)

Would you have any idea of what is happening ? I'm a bit lost, as the new code amount is pretty limited.

Thanks !