Web: Disable raycast module by default (no occlusion culling)

[akien-mga]

This means no CPU occlusion culling (and not compiling Embree), unless you compile custom export templates with module_raycast_enabled=yes.

This reduces the memory footprint significantly, and binary size.

Fixes #70621.

@Calinou I'm not too familiar with the occlusion culling and lightmap documentation, could you tell me where to add some notes that this is not supported in default Web templates?

[Calinou]

and lightmap baking IIUC, unless you compile custom export templates with
module_raycast_enabled=yes.

The CPU lightmapper hasn't been reimplemented in 4.x yet, but we don't know if we'll keep Embree when it's ported anyway. (It also isn't available in exported projects, so it would only be usable in the web editor – and it would be slow due to WebAssembly overhead.)

I'm not too familiar with the occlusion culling and lightmap documentation, could you tell me where to add some notes that this is not supported in default Web templates?

Probably in these classes' descriptions:

• https://github.com/godotengine/godot/blob/5f1e56ff26be4070496aa51095b9ac2f2b4f4ed8/doc/classes/Occluder3D.xml
• https://github.com/godotengine/godot/blob/5f1e56ff26be4070496aa51095b9ac2f2b4f4ed8/doc/classes/OccluderInstance3D.xml

And in these properties:

• godot/doc/classes/ProjectSettings.xml

  Line 2518 in 5f1e56f

  <member name="rendering/occlusion_culling/use_occlusion_culling" type="bool" setter="" getter="" default="false">

• godot/doc/classes/Viewport.xml

  Line 364 in 5f1e56f

  <member name="use_occlusion_culling" type="bool" setter="set_use_occlusion_culling" getter="is_using_occlusion_culling" default="false">

• godot/doc/classes/RenderingServer.xml

  Line 3769 in 5f1e56f

  <method name="viewport_set_use_occlusion_culling">

I can open a separate PR on godot-docs for https://docs.godotengine.org/en/latest/tutorials/3d/occlusion_culling.html.

[ryanabx]

I approve I approve I approve.

Most people exporting for web won't even know about the raycast module anyways, and this has been a compatibility issue with Webkit/iOS for a while now!

Pending the docs change, of course, but it looks like Calinou has already brought attention to that. It'd be good to put a notice in there for the person who comes by every so often who would need to know this.

[akien-mga]

Thanks @Calinou, added docs. I didn't put the note in Occluder3D and Viewport to avoid being too redundant, as both places refer to the other class or property for more details already.

[clayjohn]

We use raycasts for importing meshes with LODs. We need to check that this change does not break mesh importing

[AThousandShips]

How feasible is importing meshes with LOD on web editor?

[Calinou]

How feasible is importing meshes with LOD on web editor?

It is technically feasible, but you probably don't want to work on a project with highly complex meshes in the web editor anyway.

[ryanabx]

How feasible is importing meshes with LOD on web editor?

It is technically feasible, but you probably don't want to work on a project with highly complex meshes in the web editor anyway.

In my opinion, the limitation should be clarified in documentation. I don't know if there is a section about using the web editor, but clarifying that would be helpful. Other than that, I do think this change is for the better.

[ryanabx]

I've tested importing a gltf scene into the godot web editor on this PR.

Sample model:
https://github.com/KhronosGroup/glTF-Sample-Models/raw/master/2.0/AnimatedCube/screenshot/screenshot.gif

It imported successfully: (ignore the watermark, had to compress the video)

cube-rotate_be9MIAJl.mp4

Let me know if any more testing is required!

[ryanabx]

Follow-up:
I was asked by @clayjohn to test LOD bias on an imported gltf model. I chose a dragon model from the same repo as the rotating cube.

LOD Bias = 1:

LOD Bias = 0.001 (Lowest):

The detail does in fact change on web with this PR! I say we move forward with this :)

EDIT: Better quality images

[clayjohn]

Thanks @ryanabx for confirming that compiling out RayCast won't break our LOD import logic!

[clayjohn]

Seems like a good change. If there is demand, we can add a slim StaticRayCast fallback implementation for memory constrained systems.

[akien-mga]

Cherry-picked for 4.1.2.