Ensure shadow material and mesh are not used with wireframe mode

[clayjohn]

Fixes: #98532

In all three backends, the shared shadow material and shadow mesh were being used despite the wireframe render mode being on. This meant that for all backends shadows would never be wireframed and in the forward+ backend the depth prepass used the wrong shader + mesh.

Also, in the Compatibility renderer we weren't requesting wireframe mode at render time when using the wireframe render_mode.

	Compatibility	Mobile	Forward+
Before
After

[clayjohn]

CC @tetrapod00

[Calinou]

Tested locally (rebased on top of master 87318a2), it works as expected in all rendering methods.

Hoever, in Compatibility, when running the project, the mesh doesn't use wireframe:

It renders correctly in the editor which is also using Compatibility:

To test this, edit car_base.tscn in Truck Town and give the Body node material a custom shader with render_mode wireframe;.

[clayjohn]

@Calinou Did you remember to call RenderingServer.set_debug_generate_wireframes(true) in your project?

It is needed for the engine to generate the wireframe versions of meshes. It is true by default in the editor

[Calinou]

@Calinou Did you remember to call RenderingServer.set_debug_generate_wireframes(true) in your project?

I forgot to do that. I've added a call to RenderingServer.set_debug_generate_wireframes(true) in car_select.gd's _ready() function and it still doesn't work with this PR though, even when running the project from the editor.

PS: The method's description is outdated in the class reference.

[clayjohn]

@Calinou Did you remember to call RenderingServer.set_debug_generate_wireframes(true) in your project?

I forgot to do that. I've added a call to RenderingServer.set_debug_generate_wireframes(true) in car_select.gd's _ready() function and it still doesn't work with this PR though, even when running the project from the editor.

PS: The method's description is outdated in the class reference.

Thanks for taking a look. I will update the docs in this PR and I'll take another look to see why the setting might be ignored at run time.

[clayjohn]

@Calinou Did you remember to call RenderingServer.set_debug_generate_wireframes(true) in your project?

I forgot to do that. I've added a call to RenderingServer.set_debug_generate_wireframes(true) in car_select.gd's _ready() function and it still doesn't work with this PR though, even when running the project from the editor.

PS: The method's description is outdated in the class reference.

I took a look at truck town locally. The problem with truck town is that it is loading the mesh before RenderingServer.set_debug_generate_wireframes(true) is called. You need to set RenderingServer.set_debug_generate_wireframes(true) before loading the mesh otherwise wireframes will not be generated. Fixing that makes the demo work correctly.

[clayjohn]

Rebased and updated the documentation. This is ready for merging now

[clayjohn]

Updated docs based on the comments. Should be good to merge now

[Repiteo]

Thanks!