AngleMeasurement
Copying and pasting? We've got you covered! You can find the full source code of this tutorial here.
📐 Measuring Angles
Checking that a ramp meets accessibility requirements, verifying a roof pitch, or confirming a structural connection angle all require measuring angles between arbitrary points in a 3D model — and doing that by hand from a screenshot is inaccurate and slow. The angle measurement tool lets users place three points in the scene to define an angle and displays the result persistently as part of the 3D view. This tutorial covers configuring the tool with a color and snap mode; placing angle measurements with three double-clicks (start, vertex, end); deleting individual measurements by hovering and pressing Delete; reading all angle values from the measurements list; clearing all measurements at once; and switching between asynchronous (memory-efficient) and synchronous (faster) vertex picking modes by pre-generating mesh geometry. By the end, you'll have a fully working angle measurement tool with persistent results, keyboard deletion, and configurable picking performance.
🖖 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";
import * as FRAGS from "@thatopen/fragments";
// 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:
// `FragmentsManager.getWorker()` fetches the matching worker for this library version from unpkg and returns a blob URL.
// You can also pass your own URL to `fragments.init(...)` if you'd rather host the worker yourself.
const workerUrl = await OBC.FragmentsManager.getWorker();
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.
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 Angle Measurement Component
Measuring angles with That Open Engine is straightforward. First, retrieve the corresponding component and configure it. The angle measurement requires 3 clicks: the first point, the vertex (center of the angle), and the end point:
const measurer = components.get(OBF.AngleMeasurement);
// 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;
measurer.snappings = [FRAGS.SnappingClass.POINT];
You can create angle measurements by user interaction. Let's configure an event listener to create them when the user double clicks on the viewer container. Each angle measurement needs 3 double-clicks: start point, vertex, and end point:
container.ondblclick = () => measurer.create();
📄 The Measurements List
Whenever you create a measurement using the component, it is automatically added to a list that keeps track of all measurements. This centralized list allows you to perform various operations, such as deleting measurements, reporting all angles, and more:
const deleteMeasurements = () => {
measurer.list.clear();
};
const getAllValues = () => {
const angles: number[] = [];
for (const angle of measurer.list) {
angles.push(angle.value);
}
return angles;
};
We'll also allow deleting individual measurements by pressing the Delete or Backspace key when hovering over them:
window.onkeydown = (event) => {
if (event.code === "Delete" || event.code === "Backspace") {
measurer.delete();
}
};
🧹 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)
for (const [, model] of fragments.list) {
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.applyMatrix4(model.object.matrixWorld);
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);
}
};
await makeSynchronous(true);
🧩 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="Angle Measurement Tutorial" class="options-menu">
<bim-panel-section label="Controls">
<bim-label>Create angle: Double click 3 points</bim-label>
<bim-label>Delete measurement: 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 checked label="Synchronous Picking"
@change="${({ target }: { target: BUI.Checkbox }) => {
makeSynchronous(target.value);
}}">
</bim-checkbox>
<bim-number-input
slider step="1" label="Picker Size" value="${measurer.pickerSize}" min="2" max="20"
@change="${({ target }: { target: BUI.NumberInput }) => {
measurer.pickerSize = target.value;
}}">
</bim-number-input>
<bim-color-input
label="Color" color=#${measurer.linesMaterial.color.getHexString()}
@input="${({ target }: { target: BUI.ColorInput }) => {
measurer.color = new THREE.Color(target.color);
}}">
</bim-color-input>
<bim-dropdown
label="Units" required
@change="${({ 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="${({ target }: { target: BUI.Dropdown }) => {
const [rounding] = target.value;
measurer.rounding = rounding;
}}">
<bim-option label="0" value=0></bim-option>
<bim-option label="1" value=1></bim-option>
<bim-option label="2" value=2 checked></bim-option>
<bim-option label="3" value=3></bim-option>
<bim-option label="4" value=4></bim-option>
<bim-option label="5" value=5></bim-option>
</bim-dropdown>
<bim-button label="Delete all" @click=${() => deleteMeasurements()}></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 angles in your BIM application using the AngleMeasurement component. Congratulations! Keep going with more tutorials in the documentation.