add type is*** to d.ts

src/animation/AnimationObjectGroup.d.ts

@@ -10,6 +10,7 @@ export class AnimationObjectGroup {
 			inUse: number;
 		};
 	};
+	isAnimationObjectGroup: boolean;
 
 	add( ...args: any[] ): void;
 	remove( ...args: any[] ): void;

src/lights/AmbientLight.d.ts

@@ -15,5 +15,6 @@ export class AmbientLight extends Light {
 	constructor( color?: Color | string | number, intensity?: number );
 
 	castShadow: boolean;
+	isAmbientLight: boolean;
 
 }

src/lights/DirectionalLight.d.ts

@@ -30,5 +30,6 @@ export class DirectionalLight extends Light {
 	intensity: number;
 
 	shadow: DirectionalLightShadow;
+	isDirectionalLight: boolean;
 
 }

src/lights/DirectionalLightShadow.d.ts

@@ -4,5 +4,6 @@ import { LightShadow } from './LightShadow';
 export class DirectionalLightShadow extends LightShadow {
 
 	camera: OrthographicCamera;
+	isDirectionalLightShadow: boolean;
 
 }

src/lights/HemisphereLight.d.ts

@@ -12,5 +12,6 @@ export class HemisphereLight extends Light {
 	skyColor: Color;
 	groundColor: Color;
 	intensity: number;
+	isHemisphereLight: boolean;
 
 }

src/lights/RectAreaLight.d.ts

@@ -14,5 +14,6 @@ export class RectAreaLight extends Light {
 	width: number;
 	height: number;
 	intensity: number;
+	isRectAreaLight: boolean;
 
 }

src/lights/SpotLight.d.ts

@@ -51,5 +51,6 @@ export class SpotLight extends Light {
 	shadow: SpotLightShadow;
 	power: number;
 	penumbra: number;
+	isSpotLight: boolean;
 
 }

src/lights/SpotLightShadow.d.ts

@@ -4,5 +4,6 @@ import { LightShadow } from './LightShadow';
 export class SpotLightShadow extends LightShadow {
 
 	camera: PerspectiveCamera;
+	isSpotLightShadow: true;
 
 }

src/math/Box3.d.ts

@@ -11,6 +11,7 @@ export class Box3 {
 
 	max: Vector3;
 	min: Vector3;
+	isBox3: boolean;
 
 	set( min: Vector3, max: Vector3 ): this;
 	setFromArray( array: ArrayLike<number> ): this;

src/math/Euler.d.ts

@@ -10,6 +10,8 @@ export class Euler {
 	y: number;
 	z: number;
 	order: string;
+	isEuler: boolean;
+
 	_onChangeCallback: Function;
 
 	set( x: number, y: number, z: number, order?: string ): Euler;

src/math/Matrix3.d.ts

@@ -10,6 +10,7 @@ export interface Matrix {
 	 * Array with matrix values.
 	 */
 	elements: number[];
+	isMatrix3: boolean;
 
 	/**
 	 * identity():T;

src/math/Matrix4.d.ts

@@ -30,6 +30,8 @@ export class Matrix4 implements Matrix {
 	 */
 	elements: number[];
 
+	isMatrix4: boolean;
+
 	/**
 	 * Sets all fields of this matrix.
 	 */

src/math/Plane.d.ts

@@ -11,6 +11,7 @@ export class Plane {
 
 	normal: Vector3;
 	constant: number;
+	isPlane: boolean;
 
 	set( normal: Vector3, constant: number ): Plane;
 	setComponents( x: number, y: number, z: number, w: number ): Plane;

src/math/Quaternion.d.ts

@@ -25,6 +25,7 @@ export class Quaternion {
 	y: number;
 	z: number;
 	w: number;
+	isQuaternion: boolean;
 
 	/**
 	 * Sets values of this quaternion.

src/objects/LOD.d.ts

@@ -11,6 +11,7 @@ export class LOD extends Object3D {
 
 	levels: { distance: number; object: Object3D }[];
 	autoUpdate: boolean;
+	isLOD: boolean;
 
 	addLevel( object: Object3D, distance?: number ): this;
 	getObjectForDistance( distance: number ): Object3D | null;

src/objects/SkinnedMesh.d.ts

@@ -17,6 +17,7 @@ export class SkinnedMesh extends Mesh {
 	bindMatrix: Matrix4;
 	bindMatrixInverse: Matrix4;
 	skeleton: Skeleton;
+	isSkinnedMesh: boolean;
 
 	bind( skeleton: Skeleton, bindMatrix?: Matrix4 ): void;
 	pose(): void;

src/renderers/WebGLMultisampleRenderTarget.d.ts

@@ -11,4 +11,6 @@ export class WebGLMultisampleRenderTarget extends WebGLRenderTarget {
 		options?: WebGLRenderTargetOptions
 	);
 
+	isWebGLMultisampleRenderTarget: boolean;
+
 }

src/renderers/WebGLMultiviewRenderTarget.d.ts

@@ -12,6 +12,7 @@ export class WebGLMultiviewRenderTarget extends WebGLRenderTarget {
 		options?: WebGLRenderTargetOptions
 	);
 
+	isWebGLMultiviewRenderTarget: boolean;
 	setNumViews( numViews: number ): this;
 
 }

src/renderers/WebGLRenderTarget.d.ts

@@ -36,6 +36,8 @@ export class WebGLRenderTarget extends EventDispatcher {
 	depthBuffer: boolean;
 	stencilBuffer: boolean;
 	depthTexture: DepthTexture;
+	isWebGLRenderTarget: boolean;
+
 	/**
 	 * @deprecated Use {@link Texture#wrapS texture.wrapS} instead.
 	 */

src/scenes/Fog.d.ts

@@ -32,6 +32,8 @@ export class Fog implements IFog {
 	 */
 	far: number;
 
+	isFog: boolean;
+
 	clone(): this;
 	toJSON(): any;
 

src/scenes/FogExp2.d.ts

@@ -16,6 +16,8 @@ export class FogExp2 implements IFog {
 	 */
 	density: number;
 
+	isFogExp2: boolean;
+
 	clone(): this;
 	toJSON(): any;
 

src/scenes/Scene.d.ts

@@ -27,6 +27,8 @@ export class Scene extends Object3D {
 	background: null | Color | Texture;
 	environment: null | Texture;
 
+	isScene: boolean;
+
 	toJSON( meta?: any ): any;
 	dispose(): void;
 

src/textures/Texture.d.ts

@@ -54,6 +54,8 @@ export class Texture extends EventDispatcher {
 	encoding: TextureEncoding;
 	version: number;
 	needsUpdate: boolean;
+	isTexture: boolean;
+
 	onUpdate: () => void;
 	static DEFAULT_IMAGE: any;
 	static DEFAULT_MAPPING: any;

src/textures/VideoTexture.d.ts

@@ -21,4 +21,6 @@ export class VideoTexture extends Texture {
 		anisotropy?: number
 	);
 
+	isVideoTexture: boolean;
+
 }