Made in cycles, while using light from HDRI and Portal to direct it into the room.
Missing thing is, this window frame casting the shadow onto the floor. As far as I know, smaller light source makes the shadows sharper, but then everything else casts sharp shadow, and instead of bright, room goes dark. How could I force the window to cast the shadow ?
Hi!
The HDRi will create diffuse shadows, so you will need to add another light, you can use the sun aligner addon so it’s aligned with the sun,
I don’t know if you created the walls that aren’t visible, those will help in bouncing light and the room won’t be darker.
Another option is to do compositing, you could for example remove the HDRi and leave only the light in order to generate the shadow and then composite that with the image you have now, that way you’ll also have more control over what you can do.
Oh, I will definitelly try these solutions. Thanks 
Edit: Adding sun as another light source helped casting that shadow of the window.
Well, I just copied the arleady existing area light and scaled it to 0.01.
Sun, meanwhile, looks not realistic, only from area light, the reflection gets wider with distance, but then it tries to reflect entire window on the room. I’m only trying to get that effect like in the reference… https://prnt.sc/rwxlyl
Oh I see, for that you can use a spot light and change the size to get the non-sharp shadow borders.
Also, it seems by the image you put the light quite close to the window and on the same height, whereas in the reference seems to be well above.
Cheers
