cesium/Source/Scene/ModelExperimental/ModelExperimentalSceneGraph.js

CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.

import buildDrawCommand from "./buildDrawCommand.js";
import BoundingSphere from "../../Core/BoundingSphere.js";
import Cartesian3 from "../../Core/Cartesian3.js";
import Check from "../../Core/Check.js";
import defaultValue from "../../Core/defaultValue.js";
import defined from "../../Core/defined.js";
import ImageBasedLightingPipelineStage from "./ImageBasedLightingPipelineStage.js";
import Matrix4 from "../../Core/Matrix4.js";
import ModelExperimentalArticulation from "./ModelExperimentalArticulation.js";
import ModelColorPipelineStage from "./ModelColorPipelineStage.js";
import ModelClippingPlanesPipelineStage from "./ModelClippingPlanesPipelineStage.js";
import ModelExperimentalPrimitive from "./ModelExperimentalPrimitive.js";
import ModelExperimentalNode from "./ModelExperimentalNode.js";
import ModelExperimentalSkin from "./ModelExperimentalSkin.js";
import ModelExperimentalUtility from "./ModelExperimentalUtility.js";
import ModelRenderResources from "./ModelRenderResources.js";
import ModelSilhouettePipelineStage from "./ModelSilhouettePipelineStage.js";
import ModelSplitterPipelineStage from "./ModelSplitterPipelineStage.js";
import NodeRenderResources from "./NodeRenderResources.js";
import PrimitiveRenderResources from "./PrimitiveRenderResources.js";
import SceneMode from "../SceneMode.js";
import SplitDirection from "../SplitDirection.js";
import Transforms from "../../Core/Transforms.js";

/**
 * An in memory representation of the scene graph for a {@link ModelExperimental}
 *
 * @param {Object} options An object containing the following options
 * @param {ModelExperimental} options.model The model this scene graph belongs to
 * @param {ModelComponents} options.modelComponents The model components describing the model
 *
 * @alias ModelExperimentalSceneGraph
 * @constructor
 *
 * @private
 */
export default function ModelExperimentalSceneGraph(options) {
  options = defaultValue(options, defaultValue.EMPTY_OBJECT);
  const components = options.modelComponents;

  //>>includeStart('debug', pragmas.debug);
  Check.typeOf.object("options.model", options.model);
  Check.typeOf.object("options.modelComponents", components);
  //>>includeEnd('debug');

  /**
   * A reference to the {@link ModelExperimental} that owns this scene graph.
   *
   * @type {ModelExperimental}
   * @readonly
   *
   * @private
   */
  this._model = options.model;

  /**
   * The model components that represent the contents of the 3D model file.
   *
   * @type {ModelComponents}
   * @readonly
   *
   * @private
   */
  this._components = components;

  /**
   * Pipeline stages to apply across the model.
   *
   * @type {Object[]}
   * @readonly
   *
   * @private
   */
  this._pipelineStages = [];

  /**
   * Update stages to apply across the model.
   *
   * @type {Object[]}
   * @readonly
   *
   * @private
   */
  this._updateStages = [];

  /**
   * The runtime nodes that make up the scene graph
   *
   * @type {ModelExperimentalNode[]}
   * @readonly
   *
   * @private
   */
  this._runtimeNodes = [];

  /**
   * The indices of the root nodes in the runtime nodes array.
   *
   * @type {Number[]}
   * @readonly
   *
   * @private
   */
  this._rootNodes = [];

  /**
   * The indices of the skinned nodes in the runtime nodes array. These refer
   * to the nodes that will be manipulated by their skin, as opposed to the nodes
   * acting as joints for the skin.
   *
   * @type {Number[]}
   * @readonly
   *
   * @private
   */
  this._skinnedNodes = [];

  /**
   * The runtime skins that affect nodes in the scene graph.
   *
   * @type {ModelExperimentalSkin[]}
   * @readonly
   *
   * @private
   */
  this._runtimeSkins = [];

  /**
   * Pipeline stages to apply to this model. This
   * is an array of classes, each with a static method called
   * <code>process()</code>
   *
   * @type {Object[]}
   * @readonly
   *
   * @private
   */
  this.modelPipelineStages = [];

  // The scene graph's bounding sphere is model space, so that
  // the model's bounding sphere can be recomputed when given a
  // new model matrix.
  this._boundingSphere = undefined;

  // The 2D bounding sphere is in world space. This is checked
  // by the draw commands to see if the model is over the IDL,
  // and if so, renders the primitives using extra commands.
  this._boundingSphere2D = undefined;

  this._computedModelMatrix = Matrix4.clone(Matrix4.IDENTITY);
  this._computedModelMatrix2D = Matrix4.clone(Matrix4.IDENTITY);

  this._axisCorrectionMatrix = ModelExperimentalUtility.getAxisCorrectionMatrix(
    components.upAxis,
    components.forwardAxis,
    new Matrix4()
  );

  // Store articulations from the AGI_articulations extension
  // by name in a dictionary for easy retrieval.
  this._runtimeArticulations = {};

  initialize(this);
}

Object.defineProperties(ModelExperimentalSceneGraph.prototype, {
  /**
   * The model components this scene graph represents.
   *
   * @type {ModelComponents}
   * @readonly
   *
   * @private
   */
  components: {
    get: function () {
      return this._components;
    },
  },

  /**
   * The axis-corrected model matrix.
   *
   * @type {Matrix4}
   * @readonly
   *
   * @private
   */
  computedModelMatrix: {
    get: function () {
      return this._computedModelMatrix;
    },
  },

  /**
   * A matrix to correct from y-up in some model formats (e.g. glTF) to the
   * z-up coordinate system Cesium uses.
   *
   * @type {Matrix4}
   * @readonly
   *
   * @private
   */
  axisCorrectionMatrix: {
    get: function () {
      return this._axisCorrectionMatrix;
    },
  },

  /**
   * The bounding sphere containing all the primitives in the scene graph
   * in model space.
   *
   * @type {BoundingSphere}
   * @readonly
   *
   * @private
   */
  boundingSphere: {
    get: function () {
      return this._boundingSphere;
    },
  },
});

function initialize(sceneGraph) {
  const components = sceneGraph._components;
  const scene = components.scene;

  // If the model has a height reference that modifies the model matrix,
  // it will be accounted for in updateModelMatrix.
  const modelMatrix = sceneGraph._model.modelMatrix;
  computeModelMatrix(sceneGraph, modelMatrix);

  const articulations = components.articulations;
  const articulationsLength = articulations.length;

  const runtimeArticulations = sceneGraph._runtimeArticulations;
  for (let i = 0; i < articulationsLength; i++) {
    const articulation = articulations[i];
    const runtimeArticulation = new ModelExperimentalArticulation({
      articulation: articulation,
      sceneGraph: sceneGraph,
    });

    const name = runtimeArticulation.name;
    runtimeArticulations[name] = runtimeArticulation;
  }

  const nodes = components.nodes;
  const nodesLength = nodes.length;

  // Initialize this array to be the same size as the nodes array in
  // the model's file. This is so nodes can be stored by their index
  // in the file, for future ease of access.
  sceneGraph._runtimeNodes = new Array(nodesLength);

  const rootNodes = scene.nodes;
  const rootNodesLength = rootNodes.length;
  const transformToRoot = Matrix4.IDENTITY;
  for (let i = 0; i < rootNodesLength; i++) {
    const rootNode = scene.nodes[i];

    const rootNodeIndex = traverseSceneGraph(
      sceneGraph,
      rootNode,
      transformToRoot
    );

    sceneGraph._rootNodes.push(rootNodeIndex);
  }

  // Handle skins after all runtime nodes are created
  const skins = components.skins;
  const runtimeSkins = sceneGraph._runtimeSkins;

  const skinsLength = skins.length;
  for (let i = 0; i < skinsLength; i++) {
    const skin = skins[i];
    runtimeSkins.push(
      new ModelExperimentalSkin({
        skin: skin,
        sceneGraph: sceneGraph,
      })
    );
  }

  const skinnedNodes = sceneGraph._skinnedNodes;
  const skinnedNodesLength = skinnedNodes.length;
  for (let i = 0; i < skinnedNodesLength; i++) {
    const skinnedNodeIndex = skinnedNodes[i];
    const skinnedNode = sceneGraph._runtimeNodes[skinnedNodeIndex];

    // Use the index of the skin in the model components to find
    // the corresponding runtime skin.
    const skin = nodes[skinnedNodeIndex].skin;
    const skinIndex = skin.index;

    skinnedNode._runtimeSkin = runtimeSkins[skinIndex];
    skinnedNode.updateJointMatrices();
  }

  // Ensure articulations are applied with their initial values to their target nodes.
  sceneGraph.applyArticulations();
}

function computeModelMatrix(sceneGraph, modelMatrix) {
  const components = sceneGraph._components;
  const model = sceneGraph._model;

  sceneGraph._computedModelMatrix = Matrix4.multiplyTransformation(
    modelMatrix,
    components.transform,
    sceneGraph._computedModelMatrix
  );

  sceneGraph._computedModelMatrix = Matrix4.multiplyTransformation(
    sceneGraph._computedModelMatrix,
    sceneGraph._axisCorrectionMatrix,
    sceneGraph._computedModelMatrix
  );

  sceneGraph._computedModelMatrix = Matrix4.multiplyByUniformScale(
    sceneGraph._computedModelMatrix,
    model.computedScale,
    sceneGraph._computedModelMatrix
  );
}

const scratchComputedTranslation = new Cartesian3();

function computeModelMatrix2D(sceneGraph, frameState) {
  const computedModelMatrix = sceneGraph._computedModelMatrix;
  const translation = Matrix4.getTranslation(
    computedModelMatrix,
    scratchComputedTranslation
  );

  if (!Cartesian3.equals(translation, Cartesian3.ZERO)) {
    sceneGraph._computedModelMatrix2D = Transforms.basisTo2D(
      frameState.mapProjection,
      computedModelMatrix,
      sceneGraph._computedModelMatrix2D
    );
  } else {
    const center = sceneGraph.boundingSphere.center;
    const to2D = Transforms.wgs84To2DModelMatrix(
      frameState.mapProjection,
      center,
      sceneGraph._computedModelMatrix2D
    );
    sceneGraph._computedModelMatrix2D = Matrix4.multiply(
      to2D,
      computedModelMatrix,
      sceneGraph._computedModelMatrix2D
    );
  }

  sceneGraph._boundingSphere2D = BoundingSphere.transform(
    sceneGraph._boundingSphere,
    sceneGraph._computedModelMatrix2D,
    sceneGraph._boundingSphere2D
  );
}

/**
 * Recursively traverse through the nodes in the scene graph, using depth-first
 * post-order traversal.
 *
 * @param {ModelSceneGraph} sceneGraph The scene graph
 * @param {ModelComponents.Node} node The current node
 * @param {Matrix4} transformToRoot The transforms of this node's ancestors.
 *
 * @returns {Number} The index of this node in the runtimeNodes array.
 *
 * @private
 */
function traverseSceneGraph(sceneGraph, node, transformToRoot) {
  // The indices of the children of this node in the runtimeNodes array.
  const childrenIndices = [];
  const transform = ModelExperimentalUtility.getNodeTransform(node);

  // Traverse through scene graph.
  const childrenLength = node.children.length;
  for (let i = 0; i < childrenLength; i++) {
    const childNode = node.children[i];
    const childNodeTransformToRoot = Matrix4.multiplyTransformation(
      transformToRoot,
      transform,
      new Matrix4()
    );

    const childIndex = traverseSceneGraph(
      sceneGraph,
      childNode,
      childNodeTransformToRoot
    );
    childrenIndices.push(childIndex);
  }

  // Process node and mesh primitives.
  const runtimeNode = new ModelExperimentalNode({
    node: node,
    transform: transform,
    transformToRoot: transformToRoot,
    children: childrenIndices,
    sceneGraph: sceneGraph,
  });

  const primitivesLength = node.primitives.length;
  for (let i = 0; i < primitivesLength; i++) {
    runtimeNode.runtimePrimitives.push(
      new ModelExperimentalPrimitive({
        primitive: node.primitives[i],
        node: node,
        model: sceneGraph._model,
      })
    );
  }

  const index = node.index;
  sceneGraph._runtimeNodes[index] = runtimeNode;
  if (defined(node.skin)) {
    sceneGraph._skinnedNodes.push(index);
  }

  return index;
}

const scratchModelPositionMin = new Cartesian3();
const scratchModelPositionMax = new Cartesian3();
const scratchPrimitivePositionMin = new Cartesian3();
const scratchPrimitivePositionMax = new Cartesian3();
/**
 * Generates the {@link ModelExperimentalDrawCommand} for each primitive in the model.
 *
 * @param {FrameState} frameState The current frame state. This is needed to
 * allocate GPU resources as needed.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.buildDrawCommands = function (
  frameState
) {
  const model = this._model;
  const modelRenderResources = new ModelRenderResources(model);

  // Reset the memory counts before running the pipeline
  model.statistics.clear();

  this.configurePipeline(frameState);
  const modelPipelineStages = this.modelPipelineStages;

  let i, j, k;
  for (i = 0; i < modelPipelineStages.length; i++) {
    const modelPipelineStage = modelPipelineStages[i];
    modelPipelineStage.process(modelRenderResources, model, frameState);
  }

  const modelPositionMin = Cartesian3.fromElements(
    Number.MAX_VALUE,
    Number.MAX_VALUE,
    Number.MAX_VALUE,
    scratchModelPositionMin
  );
  const modelPositionMax = Cartesian3.fromElements(
    -Number.MAX_VALUE,
    -Number.MAX_VALUE,
    -Number.MAX_VALUE,
    scratchModelPositionMax
  );

  for (i = 0; i < this._runtimeNodes.length; i++) {
    const runtimeNode = this._runtimeNodes[i];
    runtimeNode.configurePipeline();
    const nodePipelineStages = runtimeNode.pipelineStages;

    const nodeRenderResources = new NodeRenderResources(
      modelRenderResources,
      runtimeNode
    );

    for (j = 0; j < nodePipelineStages.length; j++) {
      const nodePipelineStage = nodePipelineStages[j];

      nodePipelineStage.process(
        nodeRenderResources,
        runtimeNode.node,
        frameState
      );
    }

    const nodeTransform = runtimeNode.computedTransform;
    for (j = 0; j < runtimeNode.runtimePrimitives.length; j++) {
      const runtimePrimitive = runtimeNode.runtimePrimitives[j];

      runtimePrimitive.configurePipeline(frameState);
      const primitivePipelineStages = runtimePrimitive.pipelineStages;

      const primitiveRenderResources = new PrimitiveRenderResources(
        nodeRenderResources,
        runtimePrimitive
      );

      for (k = 0; k < primitivePipelineStages.length; k++) {
        const primitivePipelineStage = primitivePipelineStages[k];

        primitivePipelineStage.process(
          primitiveRenderResources,
          runtimePrimitive.primitive,
          frameState
        );
      }

      runtimePrimitive.boundingSphere = BoundingSphere.clone(
        primitiveRenderResources.boundingSphere,
        new BoundingSphere()
      );

      const primitivePositionMin = Matrix4.multiplyByPoint(
        nodeTransform,
        primitiveRenderResources.positionMin,
        scratchPrimitivePositionMin
      );
      const primitivePositionMax = Matrix4.multiplyByPoint(
        nodeTransform,
        primitiveRenderResources.positionMax,
        scratchPrimitivePositionMax
      );

      Cartesian3.minimumByComponent(
        modelPositionMin,
        primitivePositionMin,
        modelPositionMin
      );
      Cartesian3.maximumByComponent(
        modelPositionMax,
        primitivePositionMax,
        modelPositionMax
      );

      const drawCommand = buildDrawCommand(
        primitiveRenderResources,
        frameState
      );

      runtimePrimitive.drawCommand = drawCommand;
    }
  }

  this._boundingSphere = BoundingSphere.fromCornerPoints(
    modelPositionMin,
    modelPositionMax,
    new BoundingSphere()
  );

  this._boundingSphere = BoundingSphere.transformWithoutScale(
    this._boundingSphere,
    this._axisCorrectionMatrix,
    this._boundingSphere
  );

  model._boundingSphere = BoundingSphere.transform(
    this._boundingSphere,
    model.modelMatrix,
    model._boundingSphere
  );
  model._initialRadius = model._boundingSphere.radius;
  model._boundingSphere.radius *= model._clampedScale;
};

/**
 * Configure the model pipeline stages. If the pipeline needs to be re-run, call
 * this method again to ensure the correct sequence of pipeline stages are
 * used.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.configurePipeline = function (
  frameState
) {
  const modelPipelineStages = this.modelPipelineStages;
  modelPipelineStages.length = 0;

  const model = this._model;

  if (defined(model.color)) {
    modelPipelineStages.push(ModelColorPipelineStage);
  }

  if (model.imageBasedLighting.enabled) {
    modelPipelineStages.push(ImageBasedLightingPipelineStage);
  }

  if (model.isClippingEnabled()) {
    modelPipelineStages.push(ModelClippingPlanesPipelineStage);
  }

  if (
    defined(model.splitDirection) &&
    model.splitDirection !== SplitDirection.NONE
  ) {
    modelPipelineStages.push(ModelSplitterPipelineStage);
  }

  if (model.hasSilhouette(frameState)) {
    modelPipelineStages.push(ModelSilhouettePipelineStage);
  }
};

ModelExperimentalSceneGraph.prototype.update = function (
  frameState,
  updateForAnimations
) {
  let i, j, k;

  for (i = 0; i < this._runtimeNodes.length; i++) {
    const runtimeNode = this._runtimeNodes[i];

    for (j = 0; j < runtimeNode.updateStages.length; j++) {
      const nodeUpdateStage = runtimeNode.updateStages[j];
      nodeUpdateStage.update(runtimeNode, this, frameState);
    }

    const disableAnimations =
      frameState.mode !== SceneMode.SCENE3D && this._model._projectTo2D;
    if (updateForAnimations && !disableAnimations) {
      this.updateJointMatrices();
    }

    for (j = 0; j < runtimeNode.runtimePrimitives.length; j++) {
      const runtimePrimitive = runtimeNode.runtimePrimitives[j];
      for (k = 0; k < runtimePrimitive.updateStages.length; k++) {
        const stage = runtimePrimitive.updateStages[k];
        stage.update(runtimePrimitive, this);
      }
    }
  }
};

ModelExperimentalSceneGraph.prototype.updateModelMatrix = function (
  modelMatrix,
  frameState
) {
  computeModelMatrix(this, modelMatrix);
  if (frameState.mode !== SceneMode.SCENE3D) {
    computeModelMatrix2D(this, frameState);
  }

  // Mark all root nodes as dirty. Any and all children will be
  // affected recursively in the update stage.
  const rootNodes = this._rootNodes;
  for (let i = 0; i < rootNodes.length; i++) {
    const node = this._runtimeNodes[rootNodes[i]];
    node._transformDirty = true;
  }
};

/**
 * Updates the joint matrices for the skins and nodes of the model.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.updateJointMatrices = function () {
  const skinnedNodes = this._skinnedNodes;
  const length = skinnedNodes.length;

  for (let i = 0; i < length; i++) {
    const nodeIndex = skinnedNodes[i];
    const runtimeNode = this._runtimeNodes[nodeIndex];
    runtimeNode.updateJointMatrices();
  }
};

function forEachRuntimePrimitive(sceneGraph, callback) {
  for (let i = 0; i < sceneGraph._runtimeNodes.length; i++) {
    const runtimeNode = sceneGraph._runtimeNodes[i];
    for (let j = 0; j < runtimeNode.runtimePrimitives.length; j++) {
      const runtimePrimitive = runtimeNode.runtimePrimitives[j];
      callback(runtimePrimitive);
    }
  }
}

/**
 * Traverses through all draw commands and changes the back-face culling setting.
 *
 * @param {Boolean} backFaceCulling The new value for the back-face culling setting.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.updateBackFaceCulling = function (
  backFaceCulling
) {
  forEachRuntimePrimitive(this, function (runtimePrimitive) {
    const drawCommand = runtimePrimitive.drawCommand;
    drawCommand.backFaceCulling = backFaceCulling;
  });
};

/**
 * Traverses through all draw commands and changes the shadow settings.
 *
 * @param {ShadowMode} shadowMode The new shadow settings.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.updateShadows = function (shadowMode) {
  forEachRuntimePrimitive(this, function (runtimePrimitive) {
    const drawCommand = runtimePrimitive.drawCommand;
    drawCommand.shadows = shadowMode;
  });
};

/**
 * Traverses through all draw commands and changes whether to show the debug bounding volume.
 *
 * @param {Boolean} debugShowBoundingVolume The new value for showing the debug bounding volume.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.updateShowBoundingVolume = function (
  debugShowBoundingVolume
) {
  forEachRuntimePrimitive(this, function (runtimePrimitive) {
    const drawCommand = runtimePrimitive.drawCommand;
    drawCommand.debugShowBoundingVolume = debugShowBoundingVolume;
  });
};

/**
 * Returns an array of draw commands, obtained by traversing through the scene graph and collecting
 * the draw commands associated with each primitive.
 *
 * @param {FrameState} frameState The frame state.
 *
 * @returns {DrawCommand[]} The draw commands of the primitives in the scene graph.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.getDrawCommands = function (frameState) {
  const drawCommands = [];
  forEachRuntimePrimitive(this, function (runtimePrimitive) {
    const primitiveDrawCommand = runtimePrimitive.drawCommand;
    const result = primitiveDrawCommand.getCommands(frameState);
    drawCommands.push.apply(drawCommands, result);
  });
  return drawCommands;
};

/**
 * Sets the current value of an articulation stage.
 *
 * @param {String} articulationStageKey The name of the articulation, a space, and the name of the stage.
 * @param {Number} value The numeric value of this stage of the articulation.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.setArticulationStage = function (
  articulationStageKey,
  value
) {
  const names = articulationStageKey.split(" ");
  if (names.length !== 2) {
    return;
  }

  const articulationName = names[0];
  const stageName = names[1];

  const runtimeArticulation = this._runtimeArticulations[articulationName];
  if (defined(runtimeArticulation)) {
    runtimeArticulation.setArticulationStage(stageName, value);
  }
};

/**
 * Applies any modified articulation stages to the matrix of each node that participates
 * in any articulation.  Note that this will overwrite any nodeTransformations on participating nodes.
 *
 * @private
 */
ModelExperimentalSceneGraph.prototype.applyArticulations = function () {
  const runtimeArticulations = this._runtimeArticulations;
  for (const articulationName in runtimeArticulations) {
    if (runtimeArticulations.hasOwnProperty(articulationName)) {
      const articulation = runtimeArticulations[articulationName];
      articulation.apply();
    }
  }
};