@twinfinity/product-geometry

High-level BIM section geometry computation. Takes 3D BIM products and a cutting plane, produces categorized 2D line geometry with hidden line removal, feature edges, stair arrows, snap target finding, and room labels.

Quick Start

import { SlabSection } from '@twinfinity/product-geometry';

const section = new SlabSection(scene, {
  cutHeight: 1.5,
  depth: { above: 2.0, below: 0.3 },
});

const geometry = await section.compute(products);

// geometry.cutLines      — where walls are sliced (bold red in drawings)
// geometry.visibleLines  — edges you can see from above
// geometry.hiddenLines   — edges behind other geometry (dashed)
// geometry.silhouettes   — outer boundary outlines
// geometry.featureEdges  — sharp creases in geometry
// geometry.stairArrows   — direction arrows for stairs

Advanced configuration

import { SlabSection } from '@twinfinity/product-geometry';

const section = new SlabSection(api.viewer.scene, {
  cutHeight: 1.5,
  depth: { above: 2.0, below: 0.3 },

  lines: {
    cut: true, visible: true, hidden: true,
    silhouettes: true, featureEdges: true, stairArrows: true,
    outlineVisible: true, outlineHidden: true,
  },

  featureAngle: 30,

  classRules: [
    { match: 'ifcstair', featureAngle: 15 },
    { match: 'ifcramp', skipCutLines: true },
    { match: ['ifcrailing', 'ifccurtainwall'], renderMode: 'silhouette-only' },
  ],

  complexityDetection: {
    enabled: true,
    faceDensityThreshold: 5000,
    complexMeshMode: 'silhouette-with-features',
    structuralClasses: ['walls', 'slab', 'beam', 'columns', 'roof'],
  },

  trackProducts: true,

  onProgress: (percent, phase) => {
    updateProgressBar(percent * 100, phase);
  },
});

const geometry = await section.compute(products);

if (geometry.perProduct) {
  for (const entry of geometry.perProduct) {
    console.log(entry.product.name, 'cut:', entry.cutLines.length);
  }
}

Elevation / facade views

import { SlabSection } from '@twinfinity/product-geometry';

const elevationSection = new SlabSection(api.viewer.scene, {
  cutHeight: 0,
  viewDir: [-1, 0, 0],     // East facade
  cutOrigin: [15, 0, 0],
  depth: { above: 12.0, below: 0.5 },
  lines: {
    cut: true, visible: true, hidden: true, featureEdges: true,
    stairArrows: false, silhouettes: false,
    outlineVisible: false, outlineHidden: false,
  },
});

const facade = await elevationSection.compute(products);

Snap target finding

import { findSnapTarget, findEdgesForProduct } from '@twinfinity/product-geometry';

const edges = findEdgesForProduct(product);
const snap = findSnapTarget(edges, cursorWorldPos, 0.5);

if (snap.closest) {
  console.log('Snap type:', snap.type);    // 'vertex', 'edgeMidpoint', etc.
  console.log('Snap point:', snap.closest);
}

Documentation

• Architecture overview
• Geometry helpers reference