World Triplanar is broken with double-precision build

### Tested versions

- Reproducible in master. https://github.com/godotengine/godot/commit/c4733e80030f01182c91f69245a0e5ad247b4e07
- Reproducible in 4.2. https://github.com/godotengine/godot/commit/190cbcfd7f4ff22dc7d3a8a9058b0fbfe08fd194
- Reproducible in 4.1. https://github.com/godotengine/godot/commit/845fb92b0386b3e466f493b2158ee27b09b410ad

### System information

Mac Mini, Apple Silicon, M2 Pro

### Issue description

Triplanar broke in tests.

https://github.com/V-Sekai/godot-double-precision-test

See https://github.com/godotengine/godot/pull/90950#issuecomment-2077844399

#### Broken


#### OK

*Please ignore the rigged mesh test here.*


### Steps to reproduce

1. Ensure you have a double precision version of Godot Engine
1. Load mrp https://github.com/V-Sekai/godot-double-precision-test
2. Switch to the far version of the test scene.
3. Check that tri-planar is fuzzy on single-precision
3. Check that tri-planar is fuzzy on double-precision (bug)

### Minimal reproduction project (MRP)

https://github.com/V-Sekai/godot-double-precision-test