ViewNode

a node within a VTK scene graph

This is the superclass for all nodes within a VTK scene graph. It
contains the API for a node. It supports the essential operations such
as graph creation, state storage and traversal. Child classes adapt this
to VTK’s major rendering classes. Grandchild classes adapt those to
for APIs of different rendering libraries.

build(prepass)

Builds myself.

synchronize(prepass )

Ensures that my state agrees with my Renderable’s.

render( prepass )

Makes calls to make self visible.

parent

The view node that owns this view node

children

The View nodes gthat this nodeowns

//A factory that creates particular subclasses for different
//rendering back ends.
virtual void SetMyFactory(vtkViewNodeFactory*);
vtkGetObjectMacro(MyFactory, vtkViewNodeFactory);

getViewNodeFor ( dataObject )

Returns the view node that corresponding to the provided object
Will return NULL if a match is not found in self or descendents

getFirstAncestorOfType( type )

Find the first parent/grandparent of the desired type

renderable

The data object (thing to be rendered)

traverse ( operation )

Traverse this node with the specified pass. If you want to traverse your
children in a specific order or way override this method

traverseAllPasses()

Traverse the view tree for alldefined passes.

Source

index.js

import macro from 'vtk.js/Sources/macro';

const { vtkErrorMacro } = macro;

const PASS_TYPES = ['Build', 'Render'];

// ----------------------------------------------------------------------------
// vtkViewNode methods
// ----------------------------------------------------------------------------

function vtkViewNode(publicAPI, model) {
  // Set our className
  model.classHierarchy.push('vtkViewNode');

  // Builds myself.
  publicAPI.build = (prepass) => {};

  // Renders myself
  publicAPI.render = (prepass) => {};

  publicAPI.traverse = (renderPass) => {
    // we can choose to do special
    // traversal here based on pass
    const passTraversal = renderPass.getTraverseOperation();
    const fn = publicAPI[passTraversal];
    if (fn) {
      fn(renderPass);
      return;
    }

    // default traversal
    publicAPI.apply(renderPass, true);

    for (let index = 0; index < model.children.length; index++) {
      model.children[index].traverse(renderPass);
    }

    publicAPI.apply(renderPass, false);
  };

  publicAPI.apply = (renderPass, prepass) => {
    const customRenderPass = publicAPI[renderPass.getOperation()];
    if (customRenderPass) {
      customRenderPass(prepass, renderPass);
    }
  };

  publicAPI.getViewNodeFor = (dataObject) => {
    if (model.renderable === dataObject) {
      return publicAPI;
    }

    for (let index = 0; index < model.children.length; ++index) {
      const child = model.children[index];
      const vn = child.getViewNodeFor(dataObject);
      if (vn) {
        return vn;
      }
    }
    return undefined;
  };

  publicAPI.getFirstAncestorOfType = (type) => {
    if (!model.parent) {
      return null;
    }
    if (model.parent.isA(type)) {
      return model.parent;
    }
    return model.parent.getFirstAncestorOfType(type);
  };

  publicAPI.addMissingNode = (dobj) => {
    if (!dobj) {
      return;
    }
    const result = model._renderableChildMap.get(dobj);
    // if found just mark as visited
    if (result !== undefined) {
      result.setVisited(true);
    } else {
      // otherwise create a node
      const newNode = publicAPI.createViewNode(dobj);
      if (newNode) {
        newNode.setParent(publicAPI);
        newNode.setVisited(true);
        model._renderableChildMap.set(dobj, newNode);
        model.children.push(newNode);
      }
    }
  };

  publicAPI.addMissingNodes = (dataObjs) => {
    if (!dataObjs || !dataObjs.length) {
      return;
    }

    for (let index = 0; index < dataObjs.length; ++index) {
      const dobj = dataObjs[index];
      const result = model._renderableChildMap.get(dobj);
      // if found just mark as visited
      if (result !== undefined) {
        result.setVisited(true);
      } else {
        // otherwise create a node
        const newNode = publicAPI.createViewNode(dobj);
        if (newNode) {
          newNode.setParent(publicAPI);
          newNode.setVisited(true);
          model._renderableChildMap.set(dobj, newNode);
          model.children.push(newNode);
        }
      }
    }
  };

  publicAPI.prepareNodes = () => {
    for (let index = 0; index < model.children.length; ++index) {
      model.children[index].setVisited(false);
    }
  };

  publicAPI.setVisited = (val) => {
    model.visited = val;
  };

  publicAPI.removeUnusedNodes = () => {
    let deleted = null;
    for (let index = 0; index < model.children.length; ++index) {
      const child = model.children[index];
      const visited = child.getVisited();
      if (!visited) {
        const renderable = child.getRenderable();
        if (renderable) {
          model._renderableChildMap.delete(renderable);
        }
        if (!deleted) {
          deleted = [];
        }
        deleted.push(child);
      } else {
        child.setVisited(false);
      }
    }

    if (deleted) {
      // slow does alloc but not as common
      model.children = model.children.filter((el) => !deleted.includes(el));
    }
  };

  publicAPI.createViewNode = (dataObj) => {
    if (!model.myFactory) {
      vtkErrorMacro('Cannot create view nodes without my own factory');
      return null;
    }
    const ret = model.myFactory.createNode(dataObj);
    if (ret) {
      ret.setRenderable(dataObj);
    }
    return ret;
  };
}

// ----------------------------------------------------------------------------
// Object factory
// ----------------------------------------------------------------------------

const DEFAULT_VALUES = {
  parent: null,
  renderable: null,
  myFactory: null,
  children: [],
  visited: false,
};

// ----------------------------------------------------------------------------

function extend(publicAPI, model, initialValues = {}) {
  Object.assign(model, DEFAULT_VALUES, initialValues);

  // Build VTK API
  macro.obj(publicAPI, model);
  macro.event(publicAPI, model, 'event');

  model._renderableChildMap = new Map();

  macro.get(publicAPI, model, ['visited']);
  macro.setGet(publicAPI, model, ['parent', 'renderable', 'myFactory']);
  macro.getArray(publicAPI, model, ['children']);

  // Object methods
  vtkViewNode(publicAPI, model);
}

// ----------------------------------------------------------------------------

const newInstance = macro.newInstance(extend, 'vtkViewNode');

// ----------------------------------------------------------------------------

export default { newInstance, extend, PASS_TYPES };