Upgrade wetzel to handle 2020-12 schemas, delete draft4 schemas.

[emackey]

For consideration by @lexaknyazev and others.

This consolidates us back to a single set of schemas, dropping draft 4 and moving draft 2020-12 into their place. A new version of wetzel handles the two main changes: exclusive min/max, and consts instead of enums.

Once CI runs, I plan to diff the output.

[emackey]

Diffing the HTML artifacts from main vs. this branch, the date and git hash change of course, and there are two lines in main that say this:

<p><strong>Format</strong>: uriref</p>

Which are replaced on this branch by:

<p><strong>Format</strong>: iri-reference</p>

This is expected, and I believe this was one motivation for using the newer draft in the first place.

In other news, I tested 2020-12 on a branch of the VSCode plugin, and it seems to perform fine there too.

[lexaknyazev]

Before deleting the old schemas, we should check if other Khronos tools (e.g., glTF-CSharp-Loader) still use them.

[emackey]

@bghgary Is it possible to upgrade the CSharp loader?

Here's an exhaustive list of schema changes:

• The top of every schema file changed slightly (new draft version, new $id etc.) but CSharp might not care.
• All occurrences of "enum" : [ value ] have changed to "const" : value
• exclusiveMinimum and exclusiveMaximum have changed from a bool to the actual value (dropping the old minimum and maximum fields in cases where they were exclusive). (Example: camera.perspective.schema.json)
• In two places, format has changed from uriref to iri-reference (for example image.schema.json).

That's all that changed. The diffs are actually visible as part of this PR, since I'm replacing draft-4 here with the latest version from @lexaknyazev.

[bghgary]

@bghgary Is it possible to upgrade the CSharp loader?

It's possible for sure, but I don't have the bandwidth to do it any time soon.

[emackey]

OK. Should that hold up this PR?

[bghgary]

I'm not sure. I suppose people can checkout a commit before this PR is merged. Can we tag it somehow maybe?

[emackey]

No need for a tag. I updated the C# loader. KhronosGroup/glTF-CSharp-Loader#37

[lexaknyazev]

@bghgary @emackey
Are glTF-CSharp-Loader updates complete?

[emackey]

Yes, thanks to @bghgary who reviewed, tweaked, and merged them.

[bghgary]

Yes, thanks to @bghgary who reviewed, tweaked, and merged them.

Thanks to @emackey who did the actual change. :-)

[aaronfranke]

Is there a plan to upgrade the Khronos extension schemas to 2020-12? I noticed they are still using draft-04.

[javagl]

This is actually tracked in #2049 , but ... with little activity, and ... no volunteers yet 😬