Shader issues with certain new Android devices

[gm-bug-reporter]

Description

Many shaders simply don't work at all on a few newer-gen Android devices. The attached project works fine on all platforms and most Android phones, but not the Samsung Galaxy S23+, for example. There are a few other phones that our players have reported issues with as well but this is the only device I can personally confirm it is an issue on.

Steps To Reproduce

1. Run the project on Windows. Observe that the shader correctly re-colors the sprites (left is the original sprite, right is the re-colored/shaded sprite).

2. Run the project on a Galaxy S23+. Observe that the shader does not work.

Which version of GameMaker are you reporting this issue for?

IDE v2024.600.0.575 Runtime v2024.600.0.601

Which operating system(s) are you seeing the problem on?

Windows 10.0.19045.0

Which platform(s) are you seeing the problem on?

Android

f99862b9-3a67-41f0-b729-388441c7a28e

[jackerley]

Some Android devices run their shaders in low precision mode in order to have a longer battery life. You can avoid this by adding

precision highp float;

at the top of any pixel shader that requires a higher degree of mathematical precision. In this case adding it at the top of shd_pal_swapper.fsh resolves the issue.

Hope this helps,
Fritz

[YYBartT]

Added a paragraph on the Shaders manual page on how to set the highest precision in a shader using the code line given above.