reference `FlatShading` directly; Use comparison result directly

Importing `FlatShading` from ./constants directly, instead of accessing it from `THREE`.

and `value === FlatShading` resolves to a boolean, so no need for a ternary operation

Fix sign in Matrix4 docs

Definition of rotation matrix is incorrect

GLTFExporter: prevent exporting ShaderMaterial

Consider the case when vrdisplaypresentchange fires but device is null.

Fix #11962 Remove WebGLUtils and renderer dependency

Examples: Added Sobel Edge Detection

GLTF2Loader: Rename to GLTFLoader.

fix DragControl not work on mobile

Check asset existence to detect glTF version