Adding a simple example for how to use UIOffscreenView

[Type1J]

For AtomicGameEngine/AtomicGameEngine#1165

At first, I wanted a really nice 3D UI example. Then, I realized that such a UI might be pretty, but it would't be easy to understand how it works. These are "examples" after all.

This example should be very easy to follow. It's very short, and is based on the WebTexture3D example. It has a simple UI with a checkbox, a button that saves a PNG of the current UI, and it has a few edit fields.

[JoshEngebretson]

I am getting a black screen when trying the branch + the example, can you verify that it runs when cleanly cloned for you?

[Type1J]

I'll try a clean clone some time today. Was it on a Mac? I was on Windows. I'll try with a Mac as well.

[JoshEngebretson]

I am on Windows here, I meant a clean clone of the example just in case the project is missing something.

[Type1J]

Will do

[Type1J]

On a clean clone of the AtomicExamples repo after switching to this branch I get the correct output. I'll try updating the engine source.

[JoshEngebretson]

Hm, switched to mac and black screen here too...

[JoshEngebretson]

I can make the cube appear if I comment out: // model.material = self.uiOsView.material;

Though, that's not terribly helpful, the scene camera being parented to the node threw me for a little bit :)

[Type1J]

Clean AtomicGameEngine clone and clean AtomicExamples clone. I also pulled AtomicGameEngine upstream just to make sure that there wasn't a breaking change.

Do you know what might cause it to not work on your machine? Did the log give you any insight? What is your machine's configuration, and can you test it on another machine?

[Type1J]

The material uses an xml file that I assumed was in CoreData, but I'll try creating it in code. I'll try it on another machine as well.

[JoshEngebretson]

Hey, I plan on spending some time on this today. There isn't anything in logs, I'll verify whether I can get rendering here, if not will have a look into it since working for you, screenshot or it didn't happen 📸 😄

[Type1J]

Here's a Windows 10 machine: It wasn't a dev machine, so I installed VS2015 (with Git), and CMake. I cloned AtomicGameEngine and checked out JLS-UI-TEXTURE, then checked out AtomicExamples and checked out JLS-UI-TEXTURE on it as well. I built the editor, then opened the UITexture.atomic project, and ran it. That got me the screenshot. I was hoping that it wouldn't work so that I'd have a machine to reproduce the problem.

[JoshEngebretson]

If I enable the profiler (which uses SystemUI), I get this:

Which leads me to think there is some kind of bug, as on 2 different boxes I get a black screen without it enabled. This is on Windows and Mac, so probably not any kind of driver issue.

I plan on refactoring this a bit, so no worries, can see if that knocks issue into place.

[Type1J]

Strange, it looks horizontally flipped, and the text isn't present. Was that on a clean checkout?

[JoshEngebretson]

Yeah, clean clone of both engine/examples repos. I wouldn't worry too much about tracking down the issue, I plan on taking a pass on it now that you've done the diligence of proving/making it work :)

[Type1J]

Awesome. When it works, if you can, please let me know the details of why it didn't work for you on those machines. I'm curious.

[Type1J]

In Windows when you saw the black screen, were you building Atomic with OpenGL?

I reproduced the problem on a Mac. I'll have to look at it later, though. I'm suspecting that since the View.cpp Render() flips the camera when rendering to an OpenGL FBO that I should probably do the same. I've had some good luck proving that to myself, but I don't have all of the camera matrix values corrected just yet. I don't think that anything will need to be done for the input mapper since that's unrelated to the rendering API used.

[JoshEngebretson]

@Type1J Great, and would be good to know. I'd say not to spend a lot of time on it, as going to refactor this in a pretty major way. For example, I think we can maintain a list of root UIView's with the main view always being available... and offscreen ones added (ie. I don't think we need a specific offscreen widget class as this complicates event and rendering handling).

I'll be able to rip this out pretty fast, now that you have figured it out and shown it is possible without blowing apart the UI subsystem... hard to go back and forth on design on GitHub. I'll make a PR against your branch and we can look at changes, once I have a chance to get into them.

[JoshEngebretson]

Oh, and D3D9 on Windows

[Type1J]

Sounds good.

[Type1J]

Just for reference it's 2 different problems.

1) OpenGL currently needs a different camera matrix. 2) When the UI has no batches, it returns. It should at least reset the render targets. That's because if any offscreen views were rendered, then their render target stays active, if it doesn't.

Something else may reset them (like bringing up the debug UI, as you did, or any normal UIView which bypasses problem 2, but not problem 1.

[JoshEngebretson]

Aha! Nice sleuthing 🔍