MultipleClasses

Multiple Classes

This sample demonstrates usage of the EXT_structural_metadata extension for storing a property table with metadata that is looked up based on feature IDs.

The sample contains a glTF asset with a single mesh primitive. The mesh primitive consists of 4 quads (each formed by 2 triangles). The vertices in this mesh primitive have the usual POSITION and NORMAL vertex attributes.

Feature IDs

This example uses the same feature IDs as the the MultipleFeatureIdsAndProperties example.

Metadata Structure

The structure of the metadata is defined with an EXT_structural_metadata schema that contains two classes:

• The first class is called exampleMetadataClassA, and has the following properties:

  • a property "example_FLOAT32", with FLOAT32 components
  • a property "example_INT64", with INT64 components

• The second class is called exampleMetadataClassB, and has the following properties:

  • a property "example_UINT16", with UINT16 components
  • a property "example_FLOAT64", with, you guessed it, FLOAT64 components

Metadata Entities

The metadata entities are the actual instances of this class. They are defined with an EXT_structural_metadata property table for each class. The rows of this table correspond to the feature IDs. The columns of this table correspond to the properties of the respective class. The data for each column is stored in a standard glTF bufferView.

Based on the type information from the metadata classes, the contents of these buffer views are interpreted as follows:

The values for the property table for exampleMetadataClassA:

"example_FLOAT32" : [
    1.1, 2.2, 3.3, 4.4
],
"example_INT64" : [
    1234567, 2345678, 3456789, 4567890
]

The values for the property table for exampleMetadataClassB:

"example_UINT16" : [
    12345, 23456, 34567, 45678
],
"example_FLOAT64" : [
    1.234567, 2.345678, 3.456789, 4.567890
]

Screenshot

Example Sandcastle

This example can be viewed with the common sandcastle code.

License

CC0