Broken transition?

[protyposis]

Describe the bug
When switching presets with a soft cut, a certain type of transition seems to be broken. See the bottom area in the attached picture and video below.

Screenshots

Screen_recording_20240303_195732.mp4

Desktop (please complete the following information):
Using projectM 4.1 arm64 build on Android 11 (Nvidia Shield TV), but thought it may help to report it anyway. Please let me know if you need any other information.

ps: Thank you for this awesome piece of software!

[blaquewithaq]

It would be very helpful if you could provide the name of the preset you're displaying here!

[kblaschke]

It looks like the "plasma" transition is only affecting the bottom part of the screen, in the shape of a triangle - which would make me think that the actual transition quad is not rendered correctly for some reason. I've tested it many times, and have never seen this behavior, so can't really tell what's going on there. If you can create a OpenGL API trace for a frame with a broken transition, that'd be very helpful. I've never tested on Android and also have no knowledge about how to debug or render there. It should work similarly to other OpenGL ES platforms though.

Are all transitions behaving this way, or only this particular one?

[protyposis]

It would be very helpful if you could provide the name of the preset you're displaying here!

Here are two example presets between which this issue happened (from the cream of the crop collection; issue doesn't seem related to presets, though):

Rozzor vs Esotic - Pixie Party Light (Party Down).milk
shifter - brain coral primaries.milk

If you can create a OpenGL API trace for a frame [...] I've never tested on Android and also have no knowledge

Haven't done this either, but I'm willing to try. Does this look like it could provide what you need?

Are all transitions behaving this way, or only this particular one?

Only the "plasma" transition.

[protyposis]

The Android GPU Inspector linked above only supports selected phones. Nvidia provides its own toolkit for Android, "CodeWorks for Android" containing "Nsight Graphics 2019.3.0" with a frame debugger, but I can't get it to work with my Shield (getting stuck in "Injecting library..." step). The latest toolkit was released with Android 9, but the Shield was later updated to Android 11 - maybe they're incompatible, and toolkit support was dropped in the meantime. So, unfortunately, I'm out of ideas.

[kblaschke]

Sadly I can't really give any advice regarding Android development, that's completely outside of my current knowledge range. The only thing I could work with and at least tell what's going wrong there is some OpenGL API validation output.
There are different possibilities what causes this error, but the one I think is most probable is that the "plasma" transition shader can't be compiled and thus the draw call uses an invalid shader program, which will definitely cause undefined behavior, like the one seen in your video.

One thing you can try, if you have some way of getting STDOUT output (or using other means of Android-specific logging) out of libprojectM is that:

• Add output or logging in this catch block here and log the return value of the exception's what() method
• Recompile libprojectM and link it with your app
• Run the app

If the shader compilation fails, you'll hopefully get some output with the error message. It might well be that Android's GLSL compiler doesn't understand some parts of the plasma shader (note this file isn't the full program, just the "main" function).

If you actually get some output, I can see if I'm able to replace the offending parts with a more compatible syntax.

The next projectM release will focus on developers integrating it, specifically we'll add a proper logging API for errors and other debug messages, plus other things helpful for debugging the library from the application's side. You should subscribe to issue #732 to get updates on that particular feature, once we start/finish implementing it.

[protyposis]

• Add output or logging in this catch block here and log the return value of the exception's what() method

Unfortunately, this doesn't help - there's no exception thrown here.

[kblaschke]

There were multiple fixes being released over the past months which should have addressed the shader compilation issues.

If you still encounter this issue, feel free to provide additional information and reopen the bug report.