Add new render target types for 3D and array textures.

[Mugen87]

Fixed #23466.

Description

The PR implements WebGL3DRenderTarget and WebGLArrayRenderTarget similar to WebGLCubeRenderTarget.

The undocumented WebGLRenderTarget.setTexture() can be removed now. It was previously used to overwrite the texture reference of a render target to make webgl2_rendertarget_texture2darray.html work. This was actually a hack since the texture reference of a render target should not be replaced.

I'll add the doc pages for both new render targets if the PR gets merged.

[mrdoob]

@DavidPeicho Also FYI

[mrdoob]

I think we should probably figure out these names too...

Texture
Texture > CanvasTexture
Texture > CompressedTexture
Texture > CubeTexture 
Texture > DataTexture
Texture > DataTexture2DArray // Should this be renamed to Data2DArrayTexture? Or DataArray2DTexture?
Texture > DataTexture3D // Should this be renamed to Data3DTexture?
Texture > DepthTexture
Texture > FramebufferTexture
Texture > VideoTexture

WebGLRenderTarget
WebGLRenderTarget > WebGL2DArrayRenderTarget // New. Should it be WebGLArray2DRenderTarget?
WebGLRenderTarget > WebGL3DRenderTarget // New
WebGLRenderTarget > WebGLCubeRenderTarget
WebGLRenderTarget > WebGLMultipleRenderTargets // Could we remove this one and use an Array of WebGLRenderTargets instead? (Like how we did with MultiMaterial)

[DavidPeicho]

Just a heads up, Texture3D might still be broken on ANGLE isn't it? At least when you render to a level > 0. Linking the open bug: https://bugs.chromium.org/p/angleproject/issues/detail?id=5009

I think the same will happen with layered textures.

Regarding namings, it's not consistent with DataTexture, but technically we could go for:

Texture2DArray
Texture3D

Because those types are constructible only with raw data anyway?

[Mugen87]

Good point! However, I like the suggestion of @mrdoob to ensure the texture classes always end like so *Texture. I vote for:

DataTexture3D > 3DTexture
DataTexture2DArray > 2DArrayTexture

The two new render target names already sound good to me.

[DavidPeicho]

I don't think we can start a class with a number in JS :(

[Mugen87]

Totally forgot that 🤦 . Too bad...

[Mugen87]

How about using the same approach like for 3MFLoader? The JS file becomes 3DTexture.js but the class:

DataTexture3D > ThreeDTexture
DataTexture2DArray > ArrayTexture

[DavidPeicho]

Or we alias all the existing texture class and go for:

TextureCanvas
TextureCompressed
TextureCube
TextureData
Texture2DArray
Texture3D
...

Bigger change in the codebase, but from the user's pesperctive all the previous type exists as an alias?

[mrdoob]

If we did that we'd have to change the whole API... CameraPerspective, GeometryBox, MaterialPoints, ...

[DavidPeicho]

To me it doesn't seem confusing to only do it for textures, we don't need to do it for every class.
Otherwise we just keep the current names 😄

[mrdoob]

How about this?

Data3DTexture
DataArrayTexture
DataCubeTexture

WebGL3DRenderTarget
WebGLArrayRenderTarget
WebGLCubeRenderTarget

Basically *Array* instead of *Array2D* or *2DArray*.
Isn't 2D implied when we don't specify 3D anyway?

[Mugen87]

Basically Array instead of Array2D or 2DArray.

Sounds good!

DataCubeTexture isn't right though since you can setup a cube texture of normal HTML5 images or canvas elements.

[Mugen87]

Updated the PR with the renamed data textures.

[mrdoob]

Thanks!