documentation & further renaming

thermion_dart/lib/thermion_dart/thermion_viewer.dart

@@ -0,0 +1,759 @@
+import 'dart:math';
+
+import 'package:vector_math/vector_math_64.dart';
+import 'dart:async';
+import 'package:animation_tools_dart/animation_tools_dart.dart';
+import 'package:thermion_dart/thermion_dart/entities/filament_entity.dart';
+
+// "picking" means clicking/tapping on the viewport, and unprojecting the X/Y coordinate to determine whether any renderable entities were present at those coordinates.
+typedef FilamentPickResult = ({ThermionEntity entity, double x, double y});
+
+enum LightType {
+  SUN, //!< Directional light that also draws a sun's disk in the sky.
+  DIRECTIONAL, //!< Directional light, emits light in a given direction.
+  POINT, //!< Point light, emits light from a position, in all directions.
+  FOCUSED_SPOT, //!< Physically correct spot light.
+  SPOT,
+}
+
+// copied from filament/backened/DriverEnums.h
+enum PrimitiveType {
+  // don't change the enums values (made to match GL)
+  POINTS, //!< points
+  LINES, //!< lines
+  UNUSED1,
+  LINE_STRIP, //!< line strip
+  TRIANGLES, //!< triangles
+  TRIANGLE_STRIP, //!< triangle strip
+}
+
+enum ToneMapper { ACES, FILMIC, LINEAR }
+
+// see filament Manipulator.h for more details
+enum ManipulatorMode { ORBIT, MAP, FREE_FLIGHT }
+
+class TextureDetails {
+  final int textureId;
+
+  // both width and height are in physical, not logical pixels
+  final int width;
+  final int height;
+
+  TextureDetails(
+      {required this.textureId, required this.width, required this.height});
+}
+
+abstract class ThermionViewer {
+  
+  Future<bool> get initialized;
+
+  ///
+  /// The result(s) of calling [pick] (see below).
+  /// This may be a broadcast stream, so you should ensure you have subscribed to this stream before calling [pick].
+  /// If [pick] is called without an active subscription to this stream, the results will be silently discarded.
+  ///
+  Stream<FilamentPickResult> get pickResult;
+
+  ///
+  /// Whether the controller is currently rendering at [framerate].
+  ///
+  bool get rendering;
+
+  ///
+  /// Set to true to continuously render the scene at the framerate specified by [setFrameRate] (60 fps by default).
+  ///
+  Future setRendering(bool render);
+
+  ///
+  /// Render a single frame.
+  ///
+  Future render();
+
+  ///
+  /// Sets the framerate for continuous rendering when [setRendering] is enabled.
+  ///
+  Future setFrameRate(int framerate);
+
+  ///
+  /// Destroys/disposes the viewer (including the entire scene). You cannot use the viewer after calling this method.
+  ///
+  Future dispose();
+
+  ///
+  /// Set the background image to [path] (which should have a file extension .png, .jpg, or .ktx).
+  /// This will be rendered at the maximum depth (i.e. behind all other objects including the skybox).
+  /// If [fillHeight] is false, the image will be rendered at its original size. Note this may cause issues with pixel density so be sure to specify the correct resolution
+  /// If [fillHeight] is true, the image will be stretched/compressed to fit the height of the viewport.
+  ///
+  Future setBackgroundImage(String path, {bool fillHeight = false});
+
+  ///
+  /// Moves the background image to the relative offset from the origin (bottom-left) specified by [x] and [y].
+  /// If [clamp] is true, the image cannot be positioned outside the bounds of the viewport.
+  ///
+  Future setBackgroundImagePosition(double x, double y, {bool clamp = false});
+
+  ///
+  /// Removes the background image.
+  ///
+  Future clearBackgroundImage();
+
+  ///
+  /// Sets the color for the background plane (positioned at the maximum depth, i.e. behind all other objects including the skybox).
+  ///
+  Future setBackgroundColor(double r, double g, double b, double alpha);
+
+  ///
+  /// Load a skybox from [skyboxPath] (which must be a .ktx file)
+  ///
+  Future loadSkybox(String skyboxPath);
+
+  ///
+  /// Removes the skybox from the scene.
+  ///
+  Future removeSkybox();
+
+  ///
+  /// Loads an image-based light from the specified path at the given intensity.
+  /// Only one IBL can be active at any given time; if an IBL has already been loaded, it will be replaced.
+  ///
+  Future loadIbl(String lightingPath, {double intensity = 30000});
+
+  ///
+  /// Rotates the IBL & skybox.
+  ///
+  Future rotateIbl(Matrix3 rotation);
+
+  ///
+  /// Removes the image-based light from the scene.
+  ///
+  Future removeIbl();
+
+  ///
+  /// Add a light to the scene.
+  /// See LightManager.h for details
+  /// Note that [sunAngularRadius] is in degrees,
+  /// whereas [spotLightConeInner] and [spotLightConeOuter] are in radians
+  ///
+  Future<ThermionEntity> addLight(
+      LightType type,
+      double colour,
+      double intensity,
+      double posX,
+      double posY,
+      double posZ,
+      double dirX,
+      double dirY,
+      double dirZ,
+      {double falloffRadius = 1.0,
+      double spotLightConeInner = pi / 8,
+      double spotLightConeOuter = pi / 4,
+      double sunAngularRadius = 0.545,
+      double sunHaloSize = 10.0,
+      double sunHaloFallof = 80.0,
+      bool castShadows = true});
+
+  Future removeLight(ThermionEntity light);
+
+  ///
+  /// Remove all lights (excluding IBL) from the scene.
+  ///
+  Future clearLights();
+
+  ///
+  /// Load the .glb asset at the given path and insert into the scene.
+  ///
+  Future<ThermionEntity> loadGlb(String path, {int numInstances = 1});
+
+  ///
+  /// Create a new instance of [entity].
+  ///
+  Future<ThermionEntity> createInstance(ThermionEntity entity);
+
+  ///
+  /// Returns the number of instances of the asset associated with [entity].
+  ///
+  Future<int> getInstanceCount(ThermionEntity entity);
+
+  ///
+  /// Returns all instances of [entity].
+  ///
+  Future<List<ThermionEntity>> getInstances(ThermionEntity entity);
+
+  ///
+  /// Load the .gltf asset at the given path and insert into the scene.
+  /// [relativeResourcePath] is the folder path where the glTF resources are stored;
+  /// this is usually the parent directory of the .gltf file itself.
+  ///
+  Future<ThermionEntity> loadGltf(String path, String relativeResourcePath,
+      {bool force = false});
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future panStart(double x, double y);
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future panUpdate(double x, double y);
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future panEnd();
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future rotateStart(double x, double y);
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future rotateUpdate(double x, double y);
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future rotateEnd();
+
+  ///
+  /// Set the weights for all morph targets in [entity] to [weights].
+  /// Note that [weights] must contain values for ALL morph targets, but no exception will be thrown if you don't do so (you'll just get incorrect results).
+  /// If you only want to set one value, set all others to zero (check [getMorphTargetNames] if you need the get a list of all morph targets).
+  /// IMPORTANT - this accepts the actual ThermionEntity with the relevant morph targets (unlike [getMorphTargetNames], which uses the parent entity and the child mesh name).
+  /// Use [getChildEntityByName] if you are setting the weights for a child mesh.
+  ///
+  Future setMorphTargetWeights(ThermionEntity entity, List<double> weights);
+
+  ///
+  /// Gets the names of all morph targets for the child renderable [childEntity] under [entity].
+  ///
+  Future<List<String>> getMorphTargetNames(
+      ThermionEntity entity, ThermionEntity childEntity);
+
+  ///
+  /// Gets the names of all bones for the armature at [skinIndex] under the specified [entity].
+  ///
+  Future<List<String>> getBoneNames(ThermionEntity entity, {int skinIndex = 0});
+
+  ///
+  /// Gets the names of all glTF animations embedded in the specified entity.
+  ///
+  Future<List<String>> getAnimationNames(ThermionEntity entity);
+
+  ///
+  /// Returns the length (in seconds) of the animation at the given index.
+  ///
+  Future<double> getAnimationDuration(
+      ThermionEntity entity, int animationIndex);
+
+  ///
+  /// Animate the morph targets in [entity]. See [MorphTargetAnimation] for an explanation as to how to construct the animation frame data.
+  /// This method will check the morph target names specified in [animation] against the morph target names that actually exist exist under [meshName] in [entity],
+  /// throwing an exception if any cannot be found.
+  /// It is permissible for [animation] to omit any targets that do exist under [meshName]; these simply won't be animated.
+  ///
+  Future setMorphAnimationData(
+      ThermionEntity entity, MorphAnimationData animation,
+      {List<String>? targetMeshNames});
+
+  ///
+  /// Resets all bones in the given entity to their rest pose.
+  /// This should be done before every call to addBoneAnimation.
+  ///
+  Future resetBones(ThermionEntity entity);
+
+  ///
+  /// Enqueues and plays the [animation] for the specified bone(s).
+  /// By default, frame data is interpreted as being in *parent* bone space;
+  /// a 45 degree around Y means the bone will rotate 45 degrees around the
+  /// Y axis of the parent bone *in its current orientation*.
+  /// (i.e NOT the parent bone's rest position!).
+  /// Currently, only [Space.ParentBone] and [Space.Model] are supported; if you want
+  /// to transform to another space, you will need to do so manually.
+  ///
+  /// [fadeInInSecs]/[fadeOutInSecs]/[maxDelta] are used to cross-fade between
+  /// the current active glTF animation ("animation1") and the animation you
+  /// set via this method ("animation2"). The bone orientations will be
+  /// linearly interpolated between animation1 and animation2; at time 0, 
+  /// the orientation will be 100% animation1, at time [fadeInInSecs], the 
+  /// animation will be ((1 - maxDelta) * animation1) + (maxDelta * animation2).
+  /// This will be applied in reverse after [fadeOutInSecs]. 
+  /// 
+  ///
+  Future addBoneAnimation(ThermionEntity entity, BoneAnimationData animation,
+      {int skinIndex = 0,
+      double fadeInInSecs = 0.0,
+      double fadeOutInSecs = 0.0,
+      double maxDelta = 1.0});
+
+  ///
+  /// Gets the entity representing the bone at [boneIndex]/[skinIndex].
+  /// The returned entity is only intended for use with [getWorldTransform].
+  ///
+  Future<ThermionEntity> getBone(ThermionEntity parent, int boneIndex,
+      {int skinIndex = 0});
+
+  ///
+  /// Gets the local (relative to parent) transform for [entity].
+  ///
+  Future<Matrix4> getLocalTransform(ThermionEntity entity);
+
+  ///
+  /// Gets the world transform for [entity].
+  ///
+  Future<Matrix4> getWorldTransform(ThermionEntity entity);
+
+  ///
+  /// Gets the inverse bind (pose) matrix for the bone.
+  /// Note that [parent] must be the ThermionEntity returned by [loadGlb/loadGltf], not any other method ([getChildEntity] etc).
+  /// This is because all joint information is internally stored with the parent entity.
+  ///
+  Future<Matrix4> getInverseBindMatrix(ThermionEntity parent, int boneIndex,
+      {int skinIndex = 0});
+
+  ///
+  /// Sets the transform (relative to its parent) for [entity].
+  ///
+  Future setTransform(ThermionEntity entity, Matrix4 transform);
+
+  ///
+  /// Updates the bone matrices for [entity] (which must be the ThermionEntity
+  /// returned by [loadGlb/loadGltf]).
+  /// Under the hood, this just calls [updateBoneMatrices] on the Animator
+  /// instance of the relevant FilamentInstance (which uses the local
+  /// bone transform and the inverse bind matrix to set the bone matrix).
+  ///
+  Future updateBoneMatrices(ThermionEntity entity);
+
+  ///
+  /// Directly set the bone matrix for the bone at the given index.
+  /// Don't call this manually unless you know what you're doing.
+  ///
+  Future setBoneTransform(
+      ThermionEntity entity, int boneIndex, Matrix4 transform,
+      {int skinIndex = 0});
+
+  ///
+  /// Removes/destroys the specified entity from the scene.
+  /// [entity] will no longer be a valid handle after this method is called; ensure you immediately discard all references once this method is complete.
+  ///
+  Future removeEntity(ThermionEntity entity);
+
+  ///
+  /// Removes/destroys all renderable entities from the scene (including cameras).
+  /// All [ThermionEntity] handles will no longer be valid after this method is called; ensure you immediately discard all references to all entities once this method is complete.
+  ///
+  Future clearEntities();
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future zoomBegin();
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future zoomUpdate(double x, double y, double z);
+
+  ///
+  /// Called by `FilamentGestureDetector`. You probably don't want to call this yourself.
+  ///
+  Future zoomEnd();
+
+  ///
+  /// Schedules the glTF animation at [index] in [entity] to start playing on the next frame.
+  ///
+  Future playAnimation(ThermionEntity entity, int index,
+      {bool loop = false,
+      bool reverse = false,
+      bool replaceActive = true,
+      double crossfade = 0.0});
+
+  ///
+  /// Schedules the glTF animation at [index] in [entity] to start playing on the next frame.
+  ///
+  Future playAnimationByName(ThermionEntity entity, String name,
+      {bool loop = false,
+      bool reverse = false,
+      bool replaceActive = true,
+      double crossfade = 0.0});
+
+  Future setAnimationFrame(
+      ThermionEntity entity, int index, int animationFrame);
+
+  Future stopAnimation(ThermionEntity entity, int animationIndex);
+  Future stopAnimationByName(ThermionEntity entity, String name);
+
+  ///
+  /// Sets the current scene camera to the glTF camera under [name] in [entity].
+  ///
+  Future setCamera(ThermionEntity entity, String? name);
+
+  ///
+  /// Sets the current scene camera to the main camera (which is always available and added to every scene by default).
+  ///
+  Future setMainCamera();
+
+  ///
+  /// Returns the entity associated with the main camera.
+  ///
+  Future<ThermionEntity> getMainCamera();
+
+  ///
+  /// Sets the current scene camera to the glTF camera under [name] in [entity].
+  ///
+  Future setCameraFov(double degrees, double width, double height);
+
+  ///
+  /// Sets the tone mapping (requires postprocessing).
+  ///
+  Future setToneMapping(ToneMapper mapper);
+
+  ///
+  /// Sets the strength of the bloom.
+  ///
+  Future setBloom(double bloom);
+
+  ///
+  /// Sets the focal length of the camera. Default value is 28.0.
+  ///
+  Future setCameraFocalLength(double focalLength);
+
+  ///
+  /// Sets the distance (in world units) to the near/far planes for the active camera. Default values are 0.05/1000.0. See Camera.h for details.
+  ///
+  Future setCameraCulling(double near, double far);
+
+  ///
+  /// Get the distance (in world units) to the near culling plane for the active camera.
+  ///
+  Future<double> getCameraCullingNear();
+
+  ///
+  /// Get the distance (in world units) to the far culling plane for the active camera.
+  ///
+  Future<double> getCameraCullingFar();
+
+  ///
+  /// Sets the focus distance for the camera.
+  ///
+  Future setCameraFocusDistance(double focusDistance);
+
+  ///
+  /// Get the camera position in world space.
+  ///
+  Future<Vector3> getCameraPosition();
+
+  ///
+  /// Get the camera's model matrix.
+  ///
+  Future<Matrix4> getCameraModelMatrix();
+
+  ///
+  /// Get the camera's view matrix. See Camera.h for more details.
+  ///
+  Future<Matrix4> getCameraViewMatrix();
+
+  ///
+  /// Get the camera's projection matrix. See Camera.h for more details.
+  ///
+  Future<Matrix4> getCameraProjectionMatrix();
+
+  ///
+  /// Get the camera's culling projection matrix. See Camera.h for more details.
+  ///
+  Future<Matrix4> getCameraCullingProjectionMatrix();
+
+  ///
+  /// Get the camera's culling frustum in world space. Returns a (vector_math) [Frustum] instance where plane0-plane6 define the left, right, bottom, top, far and near planes respectively.
+  /// See Camera.h and (filament) Frustum.h for more details.
+  ///
+  Future<Frustum> getCameraFrustum();
+
+  ///
+  /// Set the camera position in world space. Note this is not persistent - any viewport navigation will reset the camera transform.
+  ///
+  Future setCameraPosition(double x, double y, double z);
+
+  ///
+  /// Get the camera rotation matrix.
+  ///
+  Future<Matrix3> getCameraRotation();
+
+  ///
+  /// Repositions the camera to the last vertex of the bounding box of [entity], looking at the penultimate vertex.
+  ///
+  Future moveCameraToAsset(ThermionEntity entity);
+
+  ///
+  /// Enables/disables frustum culling. Currently we don't expose a method for manipulating the camera projection/culling matrices so this is your only option to deal with unwanted near/far clipping.
+  ///
+  Future setViewFrustumCulling(bool enabled);
+
+  ///
+  /// Sets the camera exposure.
+  ///
+  Future setCameraExposure(
+      double aperture, double shutterSpeed, double sensitivity);
+
+  ///
+  /// Rotate the camera by [rads] around the given axis. Note this is not persistent - any viewport navigation will reset the camera transform.
+  ///
+  Future setCameraRotation(Quaternion quaternion);
+
+  ///
+  /// Sets the camera model matrix.
+  ///
+  Future setCameraModelMatrix(List<double> matrix);
+
+  ///
+  /// Sets the `baseColorFactor` property for the material at index [materialIndex] in [entity] under node [meshName] to [color].
+  ///
+  Future setMaterialColor(ThermionEntity entity, String meshName,
+      int materialIndex, double r, double g, double b, double a);
+
+  ///
+  /// Scale [entity] to fit within the unit cube.
+  ///
+  Future transformToUnitCube(ThermionEntity entity);
+
+  ///
+  /// Directly sets the world space position for [entity] to the given coordinates, skipping all collision detection.
+  ///
+  Future setPosition(ThermionEntity entity, double x, double y, double z);
+
+  ///
+  /// Directly sets the scale for [entity], skipping all collision detection.
+  ///
+  Future setScale(ThermionEntity entity, double scale);
+
+  ///
+  /// Directly sets the rotation for [entity] to [rads] around the axis {x,y,z}, skipping all collision detection.
+  ///
+  Future setRotation(
+      ThermionEntity entity, double rads, double x, double y, double z);
+
+  ///
+  /// Queues an update to the worldspace position for [entity] to {x,y,z}.
+  /// The actual update will occur on the next frame, and will be subject to collision detection.
+  ///
+  Future queuePositionUpdate(
+      ThermionEntity entity, double x, double y, double z,
+      {bool relative = false});
+
+  ///
+  /// Queues an update to the worldspace rotation for [entity].
+  /// The actual update will occur on the next frame, and will be subject to collision detection.
+  ///
+  Future queueRotationUpdate(
+      ThermionEntity entity, double rads, double x, double y, double z,
+      {bool relative = false});
+
+  ///
+  /// Same as [queueRotationUpdate].
+  ///
+  Future queueRotationUpdateQuat(ThermionEntity entity, Quaternion quat,
+      {bool relative = false});
+
+  ///
+  /// Enable/disable postprocessing.
+  ///
+  Future setPostProcessing(bool enabled);
+
+  ///
+  /// Set antialiasing options.
+  ///
+  Future setAntiAliasing(bool msaa, bool fxaa, bool taa);
+
+  ///
+  /// Sets the rotation for [entity] to the specified quaternion.
+  ///
+  Future setRotationQuat(ThermionEntity entity, Quaternion rotation);
+
+  ///
+  /// Reveal the node [meshName] under [entity]. Only applicable if [hide] had previously been called; this is a no-op otherwise.
+  ///
+  Future reveal(ThermionEntity entity, String? meshName);
+
+  ///
+  /// If [meshName] is provided, hide the node [meshName] under [entity], otherwise hide the root node for [entity].
+  /// The entity still exists in memory, but is no longer being rendered into the scene. Call [reveal] to re-commence rendering.
+  ///
+  Future hide(ThermionEntity entity, String? meshName);
+
+  ///
+  /// Used to select the entity in the scene at the given viewport coordinates.
+  /// Called by `FilamentGestureDetector` on a mouse/finger down event. You probably don't want to call this yourself.
+  /// This is asynchronous and will require 2-3 frames to complete - subscribe to the [pickResult] stream to receive the results of this method.
+  /// [x] and [y] must be in local logical coordinates (i.e. where 0,0 is at top-left of the ThermionWidget).
+  ///
+  void pick(int x, int y);
+
+  ///
+  /// Retrieves the name assigned to the given ThermionEntity (usually corresponds to the glTF mesh name).
+  ///
+  String? getNameForEntity(ThermionEntity entity);
+
+  ///
+  /// Sets the options for manipulating the camera via the viewport.
+  /// ManipulatorMode.FREE_FLIGHT and ManipulatorMode.MAP are currently unsupported and will throw an exception.
+  ///
+  Future setCameraManipulatorOptions(
+      {ManipulatorMode mode = ManipulatorMode.ORBIT,
+      double orbitSpeedX = 0.01,
+      double orbitSpeedY = 0.01,
+      double zoomSpeed = 0.01});
+
+  ///
+  /// Returns all child entities under [parent].
+  ///
+  Future<List<ThermionEntity>> getChildEntities(
+      ThermionEntity parent, bool renderableOnly);
+
+  ///
+  /// Finds the child entity named [childName] associated with the given parent.
+  /// Usually, [parent] will be the return value from [loadGlb]/[loadGltf] and [childName] will be the name of a node/mesh.
+  ///
+  Future<ThermionEntity> getChildEntity(
+      ThermionEntity parent, String childName);
+
+  ///
+  /// List the name of all child entities under the given entity.
+  ///
+  Future<List<String>> getChildEntityNames(ThermionEntity entity,
+      {bool renderableOnly = true});
+
+  ///
+  /// If [recording] is set to true, each frame the framebuffer/texture will be written to /tmp/output_*.png.
+  /// This will impact performance; handle with care.
+  ///
+  Future setRecording(bool recording);
+
+  ///
+  /// Sets the output directory where recorded PNGs will be placed.
+  ///
+  Future setRecordingOutputDirectory(String outputDirectory);
+
+  ///
+  /// An [entity] will only be animatable after an animation component is attached.
+  /// Any calls to [playAnimation]/[setBoneAnimation]/[setMorphAnimation] will have no visual effect until [addAnimationComponent] has been called on the instance.
+  ///
+  Future addAnimationComponent(ThermionEntity entity);
+
+  ///
+  /// Removes an animation component from [entity].
+  ///
+  Future removeAnimationComponent(ThermionEntity entity);
+
+  ///
+  /// Makes [entity] collidable.
+  /// This allows you to call [testCollisions] with any other entity ("entity B") to see if [entity] has collided with entity B. The callback will be invoked if so.
+  /// Alternatively, if [affectsTransform] is true and this entity collides with another entity, any queued position updates to the latter entity will be ignored.
+  ///
+  Future addCollisionComponent(ThermionEntity entity,
+      {void Function(int entityId1, int entityId2)? callback,
+      bool affectsTransform = false});
+
+  ///
+  /// Removes the collision component from [entity], meaning this will no longer be tested when [testCollisions] or [queuePositionUpdate] is called with another entity.
+  ///
+  Future removeCollisionComponent(ThermionEntity entity);
+
+  ///
+  /// Creates a (renderable) entity with the specified geometry and adds to the scene.
+  ///
+  Future createGeometry(List<double> vertices, List<int> indices,
+      {String? materialPath,
+      PrimitiveType primitiveType = PrimitiveType.TRIANGLES});
+
+  ///
+  /// Gets the parent transform of [child].
+  ///
+  Future<ThermionEntity?> getParent(ThermionEntity child);
+
+  ///
+  /// Sets the parent transform of [child] to [parent].
+  ///
+  Future setParent(ThermionEntity child, ThermionEntity parent);
+
+  ///
+  /// Test all collidable entities against this entity to see if any have collided.
+  /// This method returns void; the relevant callback passed to [addCollisionComponent] will be fired if a collision is detected.
+  ///
+  Future testCollisions(ThermionEntity entity);
+
+  ///
+  /// Sets the draw priority for the given entity. See RenderableManager.h for more details.
+  ///
+  Future setPriority(ThermionEntity entityId, int priority);
+
+  ///
+  /// The Scene holds all loaded entities/lights.
+  ///
+  Scene get scene;
+
+  ///
+  ///
+  ///
+  AbstractGizmo? get gizmo;
+}
+
+///
+/// For now, this class just holds the entities that have been loaded (though not necessarily visible in the Filament Scene).
+///
+abstract class Scene {
+  ///
+  /// The last entity clicked/tapped in the viewport (internally, the result of calling pick);
+  ThermionEntity? selected;
+
+  ///
+  /// A Stream updated whenever an entity is added/removed from the scene.
+  ///
+  Stream<bool> get onUpdated;
+
+  ///
+  /// A Stream containing every ThermionEntity added to the scene (i.e. via [loadGlb], [loadGltf] or [addLight]).
+  /// This is provided for convenience so you can set listeners in front-end widgets that can respond to entity loads without manually passing around the ThermionEntity returned from those methods.
+  ///
+  Stream<ThermionEntity> get onLoad;
+
+  ///
+  /// A Stream containing every ThermionEntity removed from the scene (i.e. via [removeEntity], [clearEntities], [removeLight] or [clearLights]).
+
+  Stream<ThermionEntity> get onUnload;
+
+  ///
+  /// Lists all light entities currently loaded (not necessarily active in the scene). Does not account for instances.
+  ///
+  Iterable<ThermionEntity> listLights();
+
+  ///
+  /// Lists all entities currently loaded (not necessarily active in the scene). Does not account for instances.
+  ///
+  Iterable<ThermionEntity> listEntities();
+
+  ///
+  /// Attach the gizmo to the specified entity.
+  ///
+  void select(ThermionEntity entity);
+
+  ///
+  ///
+  ///
+  void registerEntity(ThermionEntity entity);
+}
+
+abstract class AbstractGizmo {
+  bool get isActive;
+
+  void translate(double transX, double transY);
+
+  void reset();
+
+  void attach(ThermionEntity entity);
+
+  void detach();
+}