AreaMeasurement

Source

Copying and pasting? We've got you covered! You can find the full source code of this tutorial here.

📐 Measuring Areas

---

Space control is one of the most important elements of BIM applications. In this tutorial, you'll learn how to expose an area measurement tool to your end users.

🖖 Importing our Libraries

First things first, let's install all necessary dependencies to make this example work:

import * as THREE from "three";
import Stats from "stats.js";
import * as OBC from "@thatopen/components";
import * as BUI from "@thatopen/ui";
// You have to import * as OBF from "@thatopen/components-front"
import * as OBF from "../..";

🌎 Setting up a Simple Scene

To get started, let's set up a basic ThreeJS scene. This will serve as the foundation for our application and allow us to visualize the 3D models effectively:

const components = new OBC.Components();

const worlds = components.get(OBC.Worlds);
const world = worlds.create<
  OBC.SimpleScene,
  OBC.OrthoPerspectiveCamera,
  OBF.PostproductionRenderer
>();

world.scene = new OBC.SimpleScene(components);
world.scene.setup();
world.scene.three.background = null;

const container = document.getElementById("container")!;
world.renderer = new OBF.PostproductionRenderer(components, container);
world.camera = new OBC.OrthoPerspectiveCamera(components);
await world.camera.controls.setLookAt(68, 23, -8.5, 21.5, -5.5, 23);

components.init();

🛠️ Setting Up Fragments

Now, let's configure the FragmentsManager. This will allow us to load models effortlessly and start manipulating them with ease:

const githubUrl =
  "https://thatopen.github.io/engine_fragment/resources/worker.mjs";
const fetchedUrl = await fetch(githubUrl);
const workerBlob = await fetchedUrl.blob();
const workerFile = new File([workerBlob], "worker.mjs", {
  type: "text/javascript",
});
const workerUrl = URL.createObjectURL(workerFile);
const fragments = components.get(OBC.FragmentsManager);
fragments.init(workerUrl);

world.camera.controls.addEventListener("update", () => fragments.core.update());

world.onCameraChanged.add((camera) => {
  for (const [, model] of fragments.list) {
    model.useCamera(camera.three);
  }
  fragments.core.update(true);
});

fragments.list.onItemSet.add(({ value: model }) => {
  model.useCamera(world.camera.three);
  world.scene.three.add(model.object);
  fragments.core.update(true);
});

// Remove z fighting
fragments.core.models.materials.list.onItemSet.add(({ value: material }) => {
  if (!("isLodMaterial" in material && material.isLodMaterial)) {
    material.polygonOffset = true;
    material.polygonOffsetUnits = 1;
    material.polygonOffsetFactor = Math.random();
  }
});

📂 Loading Fragments Models

With the core setup complete, it's time to load a Fragments model into our scene. Fragments are optimized for fast loading and rendering, making them ideal for large-scale 3D models.

Where can I find Fragment files?

You can use the sample Fragment files available in our repository for testing. If you have an IFC model you'd like to convert to Fragments, check out the IfcImporter tutorial for detailed instructions.

const fragPaths = ["https://thatopen.github.io/engine_components/resources/frags/school_arq.frag"];
await Promise.all(
  fragPaths.map(async (path) => {
    const modelId = path.split("/").pop()?.split(".").shift();
    if (!modelId) return null;
    const file = await fetch(path);
    const buffer = await file.arrayBuffer();
    return fragments.core.load(buffer, { modelId });
  }),
);

✨ Using The Area Measurement Component

Measuring areas with That Open Engine is straightforward. First, retrieve the corresponding component and configure it if necessary:

const measurer = components.get(OBF.AreaMeasurement);
// Provide a world to create dimensions inside
measurer.world = world;
measurer.color = new THREE.Color("#494cb6");
// As a best practice, always set the enabled state after the initial config
measurer.enabled = true;

You can create dimensions both programatically or by user interaction. The most common way is by user interaction, so let's configure an event listener to create them when the user double clicks on the viewer container:

container.ondblclick = () => measurer.create();
window.addEventListener("keydown", (e) => {
  if (!(e.code === "Enter" || e.code === "NumpadEnter")) return;
  measurer.endCreation();
});

📄 The Measurements List

Whenever you create a dimension using the component, it is automatically added to a list that keeps track of all dimensions. This centralized list allows you to perform various operations, such as deleting dimensions, calculating their centers, reporting all values, and more. To illustrate this functionality, let's implement some useful methods:

const deleteDimensions = () => {
  measurer.list.clear();
};

const getAllValues = () => {
  const lengths: number[] = [];
  for (const area of measurer.list) {
    lengths.push(area.value);
  }
  return lengths;
};

Now, when a dimension gets added to the list a couple of things happen. Among them, is the calculation of a bounding box that can be used to know when the cursor is on top of the graphical display of the measurement. That is used internally by the component to allow delete a dimension that is just beneath the mouse. We'll keep it simple and bind this functionality to the keydown event, specifically it will fire when the user presses the Delete or Backspace key.

window.onkeydown = (event) => {
  if (event.code === "Delete" || event.code === "Backspace") {
    measurer.delete();
  }
};

🔗 Measurement Events

You already know anytime you create a dimension the result will get added to the list. When something happens to the list (a dimension has been added or deleted, for example) you can perform side actions by just listening to the corresponding events. Just for fun, let's zoom into the dimension once it has been created:

measurer.list.onItemAdded.add((area) => {
  if (!area.boundingBox) return;
  const sphere = new THREE.Sphere();
  area.boundingBox.getBoundingSphere(sphere);
  world.camera.controls.fitToSphere(sphere, true);
});

🧹 Synchronous Picking

---

By default, the picking is asynchronous, which means that the picking result is not available immediately. This saves some memory. However, you can enable synchronous picking by setting the pickerMode property to GraphicVertexPickerMode.SYNCHRONOUS. This will make the picking result available a lot faster. To do that, you'll need to generate the geometries of the models and add them to the world.meshes collection.

const meshes: THREE.Mesh[] = [];

// Add picking meshes (deduplicating geometries to save memory)
const model = fragments.list.values().next().value!;
const idsWithGeometry = await model.getItemsIdsWithGeometry();
const allMeshesData = await model.getItemsGeometry(idsWithGeometry);

const geometries = new Map<number, THREE.BufferGeometry>();

for (const itemId in allMeshesData) {
  const meshData = allMeshesData[itemId];
  for (const geomData of meshData) {
    if (
      !geomData.positions ||
      !geomData.indices ||
      !geomData.transform ||
      !geomData.representationId
    ) {
      continue;
    }

    const representationId = geomData.representationId;
    if (!geometries.has(representationId)) {
      const geometry = new THREE.BufferGeometry();
      geometry.setAttribute(
        "position",
        new THREE.Float32BufferAttribute(geomData.positions, 3),
      );
      geometry.setIndex(Array.from(geomData.indices));
      geometries.set(representationId, geometry);
    }

    const geometry = geometries.get(representationId)!;

    const mesh = new THREE.Mesh(geometry);
    mesh.applyMatrix4(geomData.transform);
    mesh.updateWorldMatrix(true, true);
    meshes.push(mesh);
  }
}

const pastDelay = measurer.delay;
const makeSynchronous = async (value: boolean) => {
  if (value) {
    measurer.pickerMode = OBF.GraphicVertexPickerMode.SYNCHRONOUS;
    measurer.delay = 0;
    for (const mesh of meshes) {
      world.meshes.add(mesh);
    }
    return;
  }
  measurer.pickerMode = OBF.GraphicVertexPickerMode.DEFAULT;
  measurer.delay = pastDelay;
  for (const mesh of meshes) {
    world.meshes.delete(mesh);
  }
};

🧩 Adding some UI (optional but recommended)

We will use the @thatopen/ui library to add some simple and cool UI elements to our app. First, we need to call the init method of the BUI.Manager class to initialize the library:

BUI.Manager.init();

Now we will add some UI to play around with the actions in this tutorial. For more information about the UI library, you can check the specific documentation for it!

const panel = BUI.Component.create<BUI.PanelSection>(() => {
  const onLogValues = () => {
    const data = getAllValues();
    console.log(data);
  };

  return BUI.html`
    <bim-panel active label="Area Measurement Tutorial" class="options-menu">
      <bim-panel-section label="Controls">
          <bim-label>Create dimension: Double click</bim-label>  
          <bim-label>Delete dimension: Delete</bim-label>  
      </bim-panel-section>
      
      <bim-panel-section label="Measurer">
        <bim-checkbox checked label="Enabled" 
          @change="${({ target }: { target: BUI.Checkbox }) => {
            measurer.enabled = target.value;
          }}">  
        </bim-checkbox>       
        <bim-checkbox checked label="Measurements Visible" 
          @change="${({ target }: { target: BUI.Checkbox }) => {
            measurer.visible = target.value;
          }}">  
        </bim-checkbox>  
        
        <bim-checkbox label="Synchronous Picking" 
          @change="${({ target }: { target: BUI.Checkbox }) => {
            makeSynchronous(target.value);
          }}">  
        </bim-checkbox>  
        
        <bim-color-input 
          label="Color" color=#${measurer.linesMaterial.color.getHexString()}
          @input="${({ target }: { target: BUI.ColorInput }) => {
            measurer.color = new THREE.Color(target.color);
          }}">
        </bim-color-input>
        
        <bim-dropdown 
          label="Measure Mode" required
          @change="${({ target }: { target: BUI.Dropdown }) => {
            const [mode] = target.value;
            measurer.mode = mode;
          }}"> ${measurer.modes.map(
            (mode) =>
              BUI.html`<bim-option label=${mode} value=${mode} ?checked=${mode === measurer.mode}></bim-option>`,
          )}
        </bim-dropdown>

        <bim-dropdown 
          label="Units" required
          @change="${({ target }: { target: BUI.Dropdown }) => {
            const [units] = target.value;
            measurer.units = units;
          }}">
          ${measurer.unitsList.map(
            (unit) =>
              BUI.html`<bim-option label=${unit} value=${unit} ?checked=${unit === measurer.units}></bim-option>`,
          )}
        </bim-dropdown>

        <bim-dropdown 
          label="Precision" required
          @change="${({ target }: { target: BUI.Dropdown }) => {
            const [rounding] = target.value;
            measurer.rounding = rounding;
          }}">
          <bim-option label="0" value=0></bim-option>
          <bim-option label="1" value=1></bim-option>
          <bim-option label="2" value=2 checked></bim-option>
          <bim-option label="3" value=3></bim-option>
          <bim-option label="4" value=4></bim-option>
          <bim-option label="5" value=5></bim-option>
        </bim-dropdown>

        <bim-button label="Delete all" @click=${() => deleteDimensions()}></bim-button>
        
        <bim-button label="Log Values" @click=${onLogValues}></bim-button>
      </bim-panel-section>
    </bim-panel>
  `;
});

document.body.append(panel);

And we will make some logic that adds a button to the screen when the user is visiting our app from their phone, allowing to show or hide the menu. Otherwise, the menu would make the app unusable.

const button = BUI.Component.create<BUI.PanelSection>(() => {
  return BUI.html`
      <bim-button class="phone-menu-toggler" icon="solar:settings-bold"
        @click="${() => {
          if (panel.classList.contains("options-menu-visible")) {
            panel.classList.remove("options-menu-visible");
          } else {
            panel.classList.add("options-menu-visible");
          }
        }}">
      </bim-button>
    `;
});

document.body.append(button);

⏱️ Measuring the performance (optional)

We'll use the Stats.js to measure the performance of our app. We will add it to the top left corner of the viewport. This way, we'll make sure that the memory consumption and the FPS of our app are under control.

const stats = new Stats();
stats.showPanel(2);
document.body.append(stats.dom);
stats.dom.style.left = "0px";
stats.dom.style.zIndex = "unset";
world.renderer.onBeforeUpdate.add(() => stats.begin());
world.renderer.onAfterUpdate.add(() => stats.end());

🎉 Wrap up

That's it! Now you're able to measure areas in your BIM application. Congratulations! Keep going with more tutorials in the documentation.