Don't create rendering device or parse glsl shader in headless mode

[TCROC]

This PR resolves: #98246

It appears that some recent code changes were made that parse glsl shaders in new locations as well as some logic surrounding DisplayServer::can_create_rendering_device. Both of which introduced problems when running on a machine that does not have a gpu. This may not be the correct solution so please leave your comments and / or open a different pr with the proper fix. This at least fixed it for me though. Without further ado, here is the explanation for my changes:

bool DisplayServer::can_create_rendering_device() {
	if (get_singleton()->get_name() == "headless") {
		return false;
	}

^ We can't create a DisplayServer in headless mode... at least I don't think we can. I'm mostly going off my intuitive understanding of the word Display and regarding the fact that there is no display on a headless server without a gpu. But that is grammatical rather than technical reasoning which I know does not necessarily apply in the world of software.

void BetsyCompressor::_init() {
	if (!DisplayServer::can_create_rendering_device()) {
		return;
	}

^ Don't try to initalize a new BetsyCompressor in headless mode. I found that for whatever reason, BetsyCompressor was trying to hook into the gpu on my device and crashing if it couldn't find one. This may or may not be the correct solution.

Error RDShaderFile::parse_versions_from_text(const String &p_text, const String p_defines, OpenIncludeFunction p_include_func, void *p_include_func_userdata) {
	ERR_FAIL_COND_V_EDMSG((DisplayServer::get_singleton()->get_name() == "headless"), ERR_UNAVAILABLE, "Cannot import custom .glsl shaders when running in headless mode.");
	ERR_FAIL_NULL_V(RenderingDevice::get_singleton(), ERR_UNAVAILABLE);

^ This is really the only change that I'm fairly confident in. I actually copied this ERROR_FAIL from a different area of code that prevents glsl imports in headless mode

godot/editor/import/resource_importer_shader_file.cpp

Line 95 in 04692d8

ERR_FAIL_COND_V_EDMSG((DisplayServer::get_singleton()->get_name() == "headless"), ERR_UNAVAILABLE, "Cannot import custom .glsl shaders when running in headless mode.");

And if you notice, that is actually preventing shader_file->parse_versions_from_text from being called on line 106: https://github.com/godotengine/godot/blob/04692d83cb8f61002f18ea1d954df8c558ee84f7/editor/import/resource_importer_shader_file.cpp#L106C8-L106C44

This is introduces a crash. So we might as well copy that check to the root cause method as well for stability purposes. Which is what I did in my change :)

NOTE:

The change I said I was "confident in" will no longer be necessary when this issue gets resolved: #94734

Which also happens to be an issue I opened 😎. But until then, this change is necessary to prevent crashes and increase stability.

I look forward to hearing your guys thoughts! As always, thanks for the awesome engine! :)

[clayjohn]

This looks mostly good. Just a bit more feedback to get it fully finished

[clayjohn]

Looks great! The final step before merging is to squash all the commits together so that the whole PR only contains 1 big commit with all your changes. We like to merge one commit at a time to keep the git history clean and navigable.

If you don't know how to do that, we have a helpful tutorial in the official documentation https://docs.godotengine.org/en/latest/community/contributing/pr_workflow.html#the-interactive-rebase

[TCROC]

Looks great! The final step before merging is to squash all the commits together so that the whole PR only contains 1 big commit with all your changes. We like to merge one commit at a time to keep the git history clean and navigable.

If you don't know how to do that, we have a helpful tutorial in the official documentation https://docs.godotengine.org/en/latest/community/contributing/pr_workflow.html#the-interactive-rebase

done :) Let me know if you need anything else :)

[clayjohn]

Looks great! Thank you

[TCROC]

Looks great! Thank you

You are very welcome! And thank you as well! ❤️

[Repiteo]

Thanks!