This sample demonstrates usage of the the EXT_structural_metadata extension for storing properties associated with the surface of a primitive, using a property texture.
The sample contains a glTF asset with a single mesh primitive. The mesh primitive consists of a quad (the unit square), formed by 2 triangles. The vertices in this mesh primitive have the usual POSITION, NORMAL, and TEXCOORD_0 vertex attributes.
The metadata in this example consists of a single example class inside an EXT_structural_metadata schema. This class defines properties of a building facade, namely the insideTemperature, outsideTemperature, and an insulation thickness. These first two properties are given as UINT8 values, covering the range [0,255]. The insulation is given as a normalized UINT8 value, meaning that the raw values in the range [0,255] represent values in the range [0.0, 1.0].
The values for the class properties are stored in an EXT_structural_metadata property texture. The red, green, and blue channel of this texture stores the value for the insideTemperature, outsideTemperature, and insulation, respectively.
This example can be viewed with the simple property texture sandcastle code.