Vulkan Mobile: Point rendering casts solid shadows, as opposed to point shadows

[Calinou]

Godot version

4.0.rc3

System information

Fedora 37, GeForce RTX 4090 (NVIDIA 525.85.05)

Issue description

• Related to OpenGL: Point rendering not working #73826.

This behavior is inconsistent with Forward+, which casts point shadows for materials using poin t rendering.

Forward+

Faint shadows appear for points (even the 1-pixel ones if you look carefully).

Mobile

Shadows appear solid.

Steps to reproduce

• Create a MeshInstance3D with a SphereMesh.
• Create a second MeshInstance3D with a SphereMesh. Move this sphere below the other one, and keep its default material so you can see this sphere receiving shadows from the other sphere.
• Add a BaseMaterial3D with Transform > Use Point Size enabled, then change Transform > Point Size.
• Notice shadow casting doesn't change if using the Forward Mobile rendering method.

Minimal reproduction project

test_point_rendering_mobile.zip