Added MeshMatcapMaterial

[WestLangley]

MeshMatcapMaterial supports maps, bump maps, normal maps, object-space normal maps, displacement maps, alpha maps, flat-shading, alpha test, skinning, morphs, and local and global clipping.

MeshMatcapMaterial does not respond to lights. (The matcap image file encodes baked lighting). It will cast a shadow onto an object that receives shadows (and shadow clipping works), but it will not self-shadow or receive shadows.

The included example supports drag-and-drop, so the user can easily experiment with alternate matcap image files.

[WestLangley]

If preferred, the example can be modified to use the glTF LeePerrySmith model once #14806 is merged.

[WestLangley]

Bubblegum Knight

[mrdoob]

Thanks!

[WestLangley]

@mrdoob Is referencing document here going to be a problem?

Is there another way we can have a default matcap?

This is actually not necessary. If the matcap is null, the model will render black, I guess. But for drag and drop support, ensuring the matcap was a valid texture to begin with makes things easy.

[mrdoob]

This is how it's done in WebGLTextures:
https://github.com/mrdoob/three.js/blob/dev/src/renderers/webgl/WebGLTextures.js#L31

[mrdoob]

You can probably create a DataTexture instead though.

[WestLangley]

document.createElementNS

That presupposes a document, too. Is that OK? I'm not sure of the advantage of createElementNS here...

You can probably create a DataTexture instead though.

I tried a DataTexture first, but there were errors when the user replaced the default matcap with a Texture, or when drag-and-drop was used. It is possible I did something wrong, of course...

[mrdoob]

I tried a DataTexture first, but there were errors when the user replaced the default matcap with a Texture, or when drag-and-drop was used. It is possible I did something wrong, of course...

Oh, sounds like a bug. I'll have to investigate.

[WestLangley]

I'll have to investigate.

Sweet. I appreciate that!

Here is my original attempt:

if ( this.matcap === null ) {

	this.matcap = new THREE.DataTexture( new Uint8Array( [ 255, 255, 255 ] ), 1, 1, THREE.RGBFormat, THREE.UnsignedByteType ); // white

	this.matcap.needsUpdate = true;

}

[WestLangley]

Oh, sounds like a bug. I'll have to investigate.

/bump

/ping @Mugen87 Should it be this, instead? Or doesn't it matter?

var canvas = document.createElementNS( 'http://www.w3.org/1999/xhtml', 'canvas' );

[Mugen87]

Yes, that's correct. Otherwise we assume a HTML document context. Explicitly defining the HTML namespace via createElementNS() is more robust.

[mrdoob]

Oh, sounds like a bug. I'll have to investigate.

/bump

#15313