flyingfishfinger
Posts: 26
Joined: Thu Feb 20, 2014 7:28 pm

Dual screens (any kind) for 3D?

Mon Apr 18, 2016 9:29 pm

Hi all-
I'm working on a project that I'd like to implement 3D capability on. The catch is that there would be 2 physically separate screens, so unless I provide external hardware, side-by-side HDMI wouldn't work.
I haven't played with this at all yet, I'm just exploring options. I know that Kodi as the ability to play back 3D content on the Pi, so I'm assuming the hardware is capable of generating it.
The question is, how to do it on 2 separate screens, one per eye? Ideally it would use 2 composite screens, but I'm open to HDMI solutions (or any suggestions at all, for that matter).
Thanks in advance for any musings, regarding both hardware and software issues!

Rafael

User avatar
topguy
Posts: 5967
Joined: Tue Oct 09, 2012 11:46 am
Location: Trondheim, Norway

Re: Dual screens (any kind) for 3D?

Mon Apr 18, 2016 10:26 pm

flyingfishfinger wrote: I know that Kodi as the ability to play back 3D content on the Pi, so I'm assuming the hardware is capable of generating it.
That is a statement and assumption at least I cant agree with. Kodi can "detect" HSBS (half-resolution side by side) 3D material if you name the file correctly and it adjusts the gui thereafter, but its a step from there to actually produce a proper 3D HDMI signal.

What kind of material will you be showing ? 3D graphics (OpenGL) or video ?

flyingfishfinger
Posts: 26
Joined: Thu Feb 20, 2014 7:28 pm

Re: Dual screens (any kind) for 3D?

Mon Apr 18, 2016 10:39 pm

I'd like to be able to show 3D graphics, not just video files. The software for it can come later, first I need to find out whether I can make the hardware support this at all.
I suppose I should first expand the question as to whether the Pi can generate this type of material, then ask about display options.
Thanks for pointing it out.

Rafael

Conjur
Posts: 17
Joined: Wed Apr 06, 2016 8:55 pm

Re: Dual screens (any kind) for 3D?

Tue Apr 26, 2016 2:52 am

Personally, I would write the code to display 2 images, side by side, in a single frame buffer; then "copy" portions of the framebuffer to 2x SPI-based TFT screens in userspace.

I am assuming that you are making a pair of 3d goggles, basically.. so each eye will have a separate 240x320 tft in front of it; each having a slightly different POV, to produce depth. My method is entirely in userspace; and will likely struggle to produce over 5FPS; but should be viable, depending on the purpose.

for example:
1) have your software play the videos on fb0 at:
(left) x=0,y=0,width=320,height=240
(right) x=320,y=0,width=320,height=240

Then write a short program to repeatedly copy those pixels from /dev/fb0 to your TFT screens via SPI... This gives you the capability of using the videocore for rendering.... unless you are just displaying static images; in that case, pushing them directly to the displays is far more efficient.


The short answer is yes, the Pi can have multiple displays; but the built-in video card only supports 1 natively. Additional displays take a bit of "finesse", and significant coding to make work.

V/r,
Mike

tinylcd
Posts: 206
Joined: Sat Oct 26, 2013 4:07 am

Re: Dual screens (any kind) for 3D?

Tue Apr 26, 2016 4:27 am

hello

below is a link to the product which can have 2 tft display attached to spi signals

it displays same image on both the display

http://www.neosecsolutions.com//product ... 9&cPath=20

regards
tinylcd

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