Check for GLES3 shader cache support before using it

[bitsawer]

Experimental draft PR for logging and possibly fixing some GLES3 shader cache related issues on older graphics cards and drivers. See #79115 and #78888 This is mostly for providing test PR and possibly builds for those who can't build their own Godot engine.

This PR adds heavy logging as it seems some drivers seem to blow up when attempting to use their shader cache. Also adds is_shader_cache_supported() function which tries to test if some cache related values are available before attempting to cache shader data. It seems that many reported issues are related to devices that report GL_NUM_PROGRAM_BINARY_FORMATS to be zero, see https://registry.khronos.org/OpenGL/extensions/ARB/ARB_get_program_binary.txt, so in these cases it might be best not to use cache at all.

[clayjohn]

I guess you can remove these before users try this out

[bitsawer]

I left them there for now to make sure that if people post their logs they have used --verbose flag and 2>&1 error redirect on Windows, I'll remove them with other logging if we want to merge some version of this PR at some point.

[clayjohn]

This looks super helpful.

I guess what we should do is get it to a place where it provides a ton of info for debugging. distribute binaries to affected users, then in a final version trim down the debug information to just what is most useful and use print_verbose. Is that what you have in mind?

[clayjohn]

I guess this can also be calculated at startup (and then cached) here

godot/drivers/gles3/rasterizer_gles3.cpp

Lines 260 to 288 in 90f90cb

	{
	String shader_cache_dir = Engine::get_singleton()->get_shader_cache_path();
	if (shader_cache_dir.is_empty()) {
	shader_cache_dir = "user://";
	}
	Ref<DirAccess> da = DirAccess::open(shader_cache_dir);
	if (da.is_null()) {
	ERR_PRINT("Can't create shader cache folder, no shader caching will happen: " + shader_cache_dir);
	} else {
	Error err = da->change_dir("shader_cache");
	if (err != OK) {
	err = da->make_dir("shader_cache");
	}
	if (err != OK) {
	ERR_PRINT("Can't create shader cache folder, no shader caching will happen: " + shader_cache_dir);
	} else {
	shader_cache_dir = shader_cache_dir.path_join("shader_cache");
	bool shader_cache_enabled = GLOBAL_GET("rendering/shader_compiler/shader_cache/enabled");
	if (!Engine::get_singleton()->is_editor_hint() && !shader_cache_enabled) {
	shader_cache_dir = String(); //disable only if not editor
	}
	if (!shader_cache_dir.is_empty()) {
	ShaderGLES3::set_shader_cache_dir(shader_cache_dir);
	}
	}
	}
	}

But that wouldn't be necessary for a testing build of course.

[bitsawer]

Yep, I added some excessive logging as debugging this is partly shooting in the dark, Foxysen provided very good info in #79115 and seemed to pinpoint at least one place where things crash, so I'll try to ping them once the builds are ready in case they can test this. Finding other people to test this who suffer from the issue would also be great.

In the final version we probably don't need any extra logging at all, so let's first see if this manages to clear things out in any way.