I would like to use Sweet Home 3D to help myself in drawing the background for my comic (basically I hand trace with gimp over the image rendered image in background [:D] ).
The most logical way would had be just take a shot of the rendered room image and then sketch over it. But I also need to work on the old pages, and find the right matching prospective it's quite hard without having an overlay preview of it.
In short: I need to know how put on overlay image while I am in 3d view. The image is a png with transparency
Here's an example.

(I need to have a 3d view of a basic room with desk+window behind)
Probably I can do something alike exporting and then importing through blender... but this would be a lot of mess for each page x every panel [:((]
