3D scene goes blank when using more than 1000 MeshInstance3D's in Web Export

Tested versions

Tested on: v4.3.stable.official [77dcf97d8] (compatibility renderer) Firefox: 130.0 (64 bit) Chromium: Version 128.0.6613.119 (Official Build) Arch Linux (64-bit)

System information

Manjaro Linux #1 SMP PREEMPT_DYNAMIC Mon Aug 19 09:51:26 UTC 2024 - Wayland - GLES3 (Compatibility) - Mesa Intel(R) UHD Graphics 620 (KBL GT2) - Intel(R) Core(TM) i5-8350U CPU @ 1.70GHz (8 Threads)

Issue description

In my 3D project, I was using blender to create my level by making hundreds of copies of the same object with different offsets and rotations but using the same mesh to save on video memory. Everything worked as expected when running natively. 2D elements like Controls and Sprites still render fine on web. All 3D elements are gone and only the clear color remains on web.

Screenshot of my Blender scene with 2543 objects all using the same mesh:

After some testing, I narrowed the problem down to the number of MeshInstance3D nodes. If the scene has more than 1000 MeshInstance3Ds, the web export scene will go blank. I did not find any mention of this limitation in the documentation, github issues, or reddit posts.

Steps to reproduce

Create a new scene with a Node as root.
Attach the below script to the root node.
Set new scene as "Main Scene".
Note: you may need to set up a web export for the project.
Go to the "Remote Debug" menu.
- Click "Run in Browser".
You should see 1000 spheres set up in a grid.
Edit the root node script to comment out add_generated_meshes(1000) and un-comment add_generated_meshes(1001).
You should see a gray screen without 1001 spheres.

Minimal reproduction project (MRP)

Add the following script to a root node of an empty scene.

extends Node

func _ready() -> void:
  add_camera()
  add_sun()

  # Works in web export:
  add_generated_meshes(1000)  # Shows 1000 spheres
  # Doesn't work in web export:
  # add_generated_meshes(1001)  # Shows only clear color background

  print(get_meshinstance_count())  

func get_meshinstance_count() -> int:
  var count: int = 0
  for child: Node in get_all_children(get_tree().root):
    if child is MeshInstance3D:
      count += 1
  return count

func get_all_children(node: Node) -> Array[Node]:
  var nodes : Array[Node] = []
  for N: Node in node.get_children(true):
    if N.get_child_count() > 0:
      nodes.append(N)
      nodes.append_array(get_all_children(N))
    else:
      nodes.append(N)
  return nodes

func add_camera() -> void:
  var camera: Camera3D = Camera3D.new()
  add_child(camera)
  camera.global_position = Vector3(0, 0, 50)

func add_sun() -> void:
  var sun: DirectionalLight3D = DirectionalLight3D.new()
  add_child(sun)
  sun.global_rotation_degrees = Vector3(-50, 0, 0)

func add_generated_meshes(count: int) -> void:
  var width: int = sqrt(count) as int
  for i: int in range(0, count):
    var mesh: MeshInstance3D = MeshInstance3D.new()
    mesh.mesh = SphereMesh.new()
    add_child(mesh)
    mesh.global_position = Vector3(
      i%width - width/2.0,
      floorf((i as float)/width) - width/2.0,
      0
    )

godotengine / godot