RoundedBoxGeometry: add type, parameters and toJSON

[vis-prime]

Description

RoundedBoxGeometry's parameters object by default holds BoxGeometry's parameters (since it extends BoxGeometry).
As a result:

• the segments and radius values passed in the constructor are lost after geometry is created.
• The toJSON method returns data relevant to creating a BoxGeometry.

This PR

• Makes the parameters key hold the actual values passed to create the geometry.
• Sets geometry.type to RoundedBoxGeometry instead of BoxGeometry.
• The two changes above consequently fix the toJSON method and make it return the correct data.
• The updated fromJSON method now returns the correct RoundedBoxGeometry instance instead of a BoxGeometry.

---

The geometry.parameters before and after for new RoundedBoxGeometry(1, 2, 3, 4, 0.125) :

---

Output from .toJSON():

---

Output from RoundedBoxGeometry.fromJSON(data) Before and after:

[vis-prime]

@Mugen87
It looks like #31319 introduces normal/shading artifacts.

Reverting this line:

super(width, height, depth, totalSegments, totalSegments, totalSegments)

Back to the original:

super(1, 1, 1, totalSegments, totalSegments, totalSegments)

fixes the issue .

Should we include this change in this PR or open a new one or something else?

2025-07-01.13-23-48.mp4

[Mugen87]

Should we include this change in this PR or open a new one or something else?

Let's include it! Good find, btw! 👍