Performance Optimization for Android Deployment

[MizunagiKB]

Thank you so much! I was just about to report/ask about poor performance on Android. In a blank project with no code, and just the "Niziiro Mao" model, I was getting only 7 fps in Bluestacks on Vulkan and 9 fps on OpenGL, on my pc (Ryzen 5 5600, 3060 Ti).
Nothing I tried seemed to improve the situation - changing the project resolution, model texture size, or mask viewport size made no difference. But i tried this code and even though on OpenGL it improved slightly to 25fps, on Vulkan, it jumped to 80fps with a static model. Now, making a game in Godot with a Live2D model and releasing it on Android is actually plausible.
FPS drops when motion is applied or parameters are changed, sometimes going as low as 20fps, but adjusting the mask viewport size significantly improves performance, although it breaks the eyes' rendering.
I'm not much of a programmer myself, so may I ask if there's anything I can do on my part to improve performance even more?
In any case, i hope you will continue the development and make it even more optimized if possible.
Thank you erodozer for this fix and all the improvements you bring to this project!
And thank you MizunagiKB for your huge work, that is making this addon in the first place and your continuous support of it!

Originally posted by @cigarette-craver in #140 (comment)

[MizunagiKB]

@cigarette-craver

Performance Differences in Live2D Model Rendering

The rendering of Live2D models does not change in terms of vertex count or texture usage during rendering.
However, rendering performance may vary due to the following factors:

1. Number of Parts

Rendering is performed on a per-part basis. Consequently, the more parts a Live2D model uses, the heavier the rendering process becomes. (In Godot, parts are treated as Nodes, so a higher number of parts results in more Nodes.)

For example, when aiming for detailed movement, such as finely animated hair, parts may be divided into smaller segments. Similarly, techniques like overlaying semi-transparent shadow images for added depth are often used in Live2D models.
While these techniques enhance visual quality, they may be disadvantageous when rendering speed is critical.

In environments with limited processing power, lowering the texture resolution might also be an effective approach.

2. Number of Masks Used

Masks are dynamically generated. Therefore, reducing the number of mask usage areas can lighten the rendering load.

To determine how much rendering speed varies between models, it is recommended to try other models besides "Niziiro Mao."

Mask Viewport Size and Eye Rendering Issues

Regarding the issue where the rendering of the eyes becomes distorted with certain mask viewport sizes, it is possible that the size is too small, or that the mask viewport is not being generated correctly in your environment.

If the distortion occurs only at specific mask viewport sizes, it might be a bug specific to certain environments. While we are unable to confirm behavior on Android and cannot provide support for it at this time, we would appreciate it if you could report the issue for information-sharing purposes.