GLTFTexture represents a texture in a GLTF file. $DOCS_URL/tutorials/io/runtime_file_loading_and_saving.html ID of the texture sampler to use when sampling the image. If -1, then the default texture sampler is used (linear filtering, and repeat wrapping in both axes). The index of the image associated with this texture, see [method GLTFState.get_images]. If -1, then this texture does not have an image assigned.