The Draco-compressed version of the VirtualCity may be invalid:
- The mesh with index
15 refers to accessor 202 as its indices
- The accessor with index
202 contains a max: [ 228 ]
- The mesh refers to the accessor with index
203 as its NORMAL
- The accessor with index
203 (just below the indices) claims a count of 140 - meaning that some indices will be out of bounds for that
For comparison: In the glTF version (default, uncompressed):
- The mesh with index 15 refers to accessor
88 as its indices
- The accessor with index
88 contains the same max: [ 228 ]
- The mesh refers to the accessor with index
89 as its NORMAL
- But the accessor with index
89 (just below the indices) has a count of 229 - just right for the maximum index of 228
Maybe I'm overlooking something in the Draco spec - something that claims that the count may be that of the compressed/reordered data or something. The Conformance section claims that a loader must ignore the data of the accessor, and use the Draco-decoded data instead - but I think that this does not imply that the count of these accessors may be wrong.
There probably aren't many people who can quickly give a 👍 or 👎 on whether this is really invalid. But I hope that it's OK to tag @lexaknyazev here...
EDIT: Mistyped "accessor" as "buffer view" in some places...
The Draco-compressed version of the
VirtualCitymay be invalid:15refers to accessor202as itsindices202contains amax: [ 228 ]203as itsNORMAL203(just below the indices) claims acountof140- meaning that some indices will be out of bounds for thatFor comparison: In the
glTFversion (default, uncompressed):88as itsindices88contains the samemax: [ 228 ]89as itsNORMAL89(just below the indices) has acountof229- just right for the maximum index of228Maybe I'm overlooking something in the Draco spec - something that claims that the
countmay be that of the compressed/reordered data or something. The Conformance section claims that a loader must ignore the data of the accessor, and use the Draco-decoded data instead - but I think that this does not imply that thecountof these accessors may be wrong.There probably aren't many people who can quickly give a 👍 or 👎 on whether this is really invalid. But I hope that it's OK to tag @lexaknyazev here...
EDIT: Mistyped "accessor" as "buffer view" in some places...