Tag materials to make them available to be applied to meshes. Use swatches to ensure your materials aren't removed when exporting.
When you tag a material with a name, you make that material available to be applied to any tagged mesh. For example by tagging a mesh named BALL, and two materials tagged BLUE and RED, you allow viewers to request the BALL with either the RED or BLUE material applied.
Warning: Take care to tag the material name itself, *not* a mesh the material is applied to.
Any materials that are not requested won't have their textures included in the generated model file, which helps reduce the transfer size to the end user.
note: In the near future properties will be able to be set dynamically on tagged materials. For example; if you had a cotton material in a range of colours, rather than creating one material for each color, you would just create a single tagged material and let the viewer set an RGB value for the diffuse channel when requesting to generate the model.
Chances are, you'll have many more materials than meshes, and most 3D editors will remove unused materials when exporting. To ensure your GLTF file includes all the materials you have tagged, we create ‘swatches’ for each material in the file.
A swatch is just a tiny mesh you tag with V[SWATCH], then apply a material to, guaranteeing the material is then available to generate variants. Swatches won't be tagged with anything else (like a tag-name), as they are just a delivery method for your tagged materials.