Check "All primitives MUST have the same number of morph targets"

[scurest]

The spec says

All primitives MUST have the same number of morph targets in the same order.

I believe that means this should be invalid

"primitives" : [
  {
    "attributes" : {
      "POSITION" : 0
    },
    "indices" : 1,
    "material" : 0
  },
  {
    "attributes" : {
      "POSITION" : 3
    },
    "indices" : 4,
    "material" : 1,
    "targets" : [
      {
        "POSITION" : 5
      }
    ]
  }
],

Example file

It passes validation when using https://github.khronos.org/glTF-Validator/ though.

[lexaknyazev]

Good catch. I think we need to clarify the spec first. Opened KhronosGroup/glTF#2154.

[scurest]

Actually I realized this is already checked, but it depends on the primitive order; it only starts checking the lengths after the first primitive with a targets. So swapping those primitives above would trigger the error. That's definitely wrong (primitive order does not affect validity) right?

[lexaknyazev]

That's definitely wrong (primitive order does not affect validity) right?

I agree that the validation bug is there but the correct report (i.e., whether the snippet above is valid or not) would depend on the clarified spec language.

[lexaknyazev]

The new version has been released.