Added a really crude demonstration of the compositor effects use case of this functionality here: godotengine/godot-demo-projects#1086

This should both work if you build the shader manually like in the post_proces_shader.gd example, as well as doing the include in a .glsl file. I'm assuming for real files they need a res::// prefix, else this means that our build in glsl include files have become reserved names.

As we lack some of the build in defines, it all does come with a bit of a manual (yet to be written), but for instance to include the scene data we get:

#version 450

#define MAX_VIEWS 2

#include "godot/scene_data_inc.glsl"

// Invocations in the (x, y, z) dimension.
layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;

layout(set = 0, binding = 0, std140) uniform SceneDataBlock {
	SceneData data;
	SceneData prev_data;
}
scene_data_block;
...

Then in code we get:

var scene_data := p_render_data.get_render_scene_data()
var scene_data_buffers: RID = scene_data.get_uniform_buffer()

To retrieve our RID, and then obviously our uniform set:

var scene_data_uniform := RDUniform.new()
scene_data_uniform.uniform_type = RenderingDevice.UNIFORM_TYPE_UNIFORM_BUFFER
scene_data_uniform.binding = 0
scene_data_uniform.add_id(scene_data_buffers)
var uniform_set := UniformSetCacheRD.get_cache(shader, 0, [scene_data_uniform])

...

rd.compute_list_bind_uniform_set(compute_list, uniform_set, 0)

Now in the shader we can access the build in scene data uniform buffer (view in this case coming from our push constant):

mat4 inv_projection_matrix = scene_data_block.data.inv_projection_matrix_view[int(params.view)];

Rebased and added some more code that is needed for custom shader templates.

@clayjohn Would you mind reviewing this, I'd like to get this merged as the functionality added here is already useful even before we add custom shader templates.

Forgot to put some extra info here after our rendering meeting a month ago.
Decision was made to change this PR so the include files are held within their own ShaderIncludeDB class.
Just haven't had time to do this yet.

Rofl, edited the OP to include an example only to realise I had previously provided an example. A well, makes more sense in the OP. :)

This is ready for review again, with changes applied as discussed in rendering meeting from some time ago.

Thanks!

Merged a bit too soon with the "built in" typo but ah well

h the "built in" typo but a

Shhhh, you can just fix it separately :P