BufferAttribute setVector & setColor convenience methods

[Kodub]

Description

This PR adds new convenience methods to BufferAttribute & InterleavedBufferAttribute.

• setVector2()
• setVector3()
• setVector4()
• setColor()

These helps simplify setting vectors and colors which seem to be a quite common pattern as most instances of setXYZ are possible to change into these new convenience methods.

Before:

const v = new THREE.Vector3(1, 2, 3);
attribute.setXYZ(0, v.x, v.y, v.z);

const c = new THREE.Color(0.1, 0.2, 0.3);
attribute.setXYZ(1, c.r, c.g, c.b);

After:

const v = new THREE.Vector3(1, 2, 3);
attribute.setVector3(0, v);

const c = new THREE.Color(0.1, 0.2, 0.3);
attribute.setColor(1, c);

Advantages

• Shorter code
• Helps prevent hard to spot mistakes. For example: attribute.setXYZ(0, v.x, v.x, v.z);

Discussion points

• Other possible names are setXYZFromVector3 and setXYZFromColorRGB. Would these names be preferred to make it clearer that these are convenience methods for setXYZ?
• Right now these methods simply call their respective setXYZ methods. The extra function call might introduce a small performance overhead.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	361.21 85.78	361.21 85.78	+0 B +0 B
WebGPU	637.46 177.05	637.46 177.05	+0 B +0 B
WebGPU Nodes	635.58 176.76	635.58 176.76	+0 B +0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	493.71 120.45	493.89 120.46	+184 B +13 B
WebGPU	709.2 191.87	709.59 191.88	+386 B +12 B
WebGPU Nodes	658.42 179.16	658.81 179.16	+386 B +0 B

[gkjohnson]

If convenience of setting BufferAttribute values here is the primary goal of this change I'll point out that using the spread operator serves this use quite well, in my opinion:

const pos = new Vector3();
posAttr.setXYZ( i, ...pos );

[WestLangley]

Note that we have similar convenience methods. See #25637. I'd follow the same naming conventions for consistency.

[Mugen87]

TBH, I'm not in favor of this PR since it bloats the API for no adequately good reason. The spread operator wasn't available in earlier days of three.js but now it's safe to use it and can avoid such verbose APIs.

Regarding the math classes, there is e.g. no need for setFromColor() since you can now do this:

vector.set( ... color );

https://jsfiddle.net/0hdq9sLr/

[Kodub]

Note that the spread operator syntax does not work in this case when using TypeScript, since it can't guarantee that the iterator will return enough elements.

From my understanding this can't be fixed on the TS side either, because TS does not currently support tuple iterators.
See: microsoft/TypeScript#42033

This syntax works though:
attribute.setXYZ(0, ...v.toArray());

Either way, I think it's not entirely clear that the spread operator can be used like this, since the user would have to know that the Vector implements an iterator. But maybe it shouldn't be up to the library to educate users.