Android application on multiple displays

Hi everyone,

I have an Android tablet application already connected via Bluetooth with another one on a mobile.
I need to put a specific view from the tablet (i.e. everything but the UI) to an external monitor.

So, the complete chain is:

MOBILE (connected via Bluetooth to) TABLET (connected via something to) EXTERNAL MONITOR.

I'm currently using nativebt plugin for the Bluetooth connection, so as far as I know I can't use an additional Bluetooth connection on the external monitor.

My thought was a physical cable, but I'm not sure I can address different renderings to multiple displays on Android.

Here I undestand I can't:
https://docs.unity3d.com/Manual/MultiDisplay.html

while here i understand I can:
https://docs.unity3d.com/ScriptReference/Display.html

Any idea?

 

Did you find your answer?

 

I need to stream the display from my Android device application to a projector with WiFi, could you tell me an easier way?

 

A bit late in the game but if anyone else is looking: recent android devices and displays supports Miracast or a variant (e.g. Samsung's SmartView) so it's pretty straightforward. Sometime the screen mirroring activation is a bit buried in the devices parameters, but you can start the whole thing by code with a simple native call (see here).

Back to the original question: in 2018.3.12, once the screen mirroring is activated you can very easily able to have different content on the device and on the external monitor using the Display class. In my case, I used a camera to grab the content I wanted to display on the tv screen. These few line of code did the trick:

Code (CSharp):

1. if (Display.displays.Length <= 1) return;
2.  
3.             Display tv = Display.displays[1];
4.          
5.             tv.SetRenderingResolution(1280, 720);
6.             _CastCam.SetTargetBuffers(tv.colorBuffer, tv.depthBuffer);

Sadly, in 2019 this code doesn't work anymore as Display.displays.Length remains at 1.

 

I made a sample project for the bug report (first in 2018.3.12f1 that I upgraded to 2019.2.12f1) and the issue did not occur.

I made a bit of digging and found out the culprit: the "Graphics API" default values (in the player settings) for a new 2019.2.12f1 project have "Vulkan" listed first. Changing the API orders or enabling "Auto Graphics API" solves the issue for 2019.2.12f1 and setting Vulkan as the first API in 2018.3.12f1 creates the issue.

TL;DR: having different content on different displays does not work with Vulkan on Android, regardless of version.

Bug ID is #1198601

 

I am experiencing the same problem with iOS Metal (Airplay).