I'm trying to make a logo that will be on the header of a website. What I'd like to achieve, and the reason I'm using Blender, is the projected shadows on the background looking perfectly real (as opposed to doing a drop-shadow in Photoshop).
The only thing is, the background has to be transparent because the website might use different background colors / gradients that make it impossible to match with the exported 3D background.
I made this dummy file (not the real logo... duh!):
If I use the file as is, the grey borders of the image will be impossible to match with the website's background color. Here what I want:
So obviously, I tried masking the plane, which made the shadows disappear. I tried having a plane set to glass, which didn't work either. And I looked around for a similar question, but didn't find one.
I am not trying to render an object without a shadow, or a shadow without the emitter object. I've seen this question which has a very difficult solution to this problem, and this one that is very similar but in Blender Internal. This one is similar too but has never been solved. I'm only a beginner at Compositor, and I'm trying to learn more any chance I get, so any solution in Compositor is welcome if detailed enough. Although if there's a simpler or faster way, it's welcome too!