@ifc-lite/drawing-2d

@ifc-lite/drawing-2d

2D architectural drawings from 3D IFC models. Generates floor plans and sections as vector SVG with cut lines, projection lines, hidden lines, material hatching, and architectural symbols (door swings, stair arrows, window frames). Optionally GPU-accelerated.

Installation

npm install @ifc-lite/drawing-2d

Floor plan

import { generateFloorPlan, exportToSVG, PAPER_SIZES, COMMON_SCALES } from '@ifc-lite/drawing-2d';

// Cut at 1.2 m above floor level (standard architectural plan height)
const drawing = await generateFloorPlan(meshes, 1.2, {
  includeHiddenLines: true,
  includeMaterialHatching: true,
});

const svg = exportToSVG(drawing, {
  paperSize: PAPER_SIZES.A3_LANDSCAPE,
  scale: COMMON_SCALES.find((s) => s.factor === 50), // 1:50
  showHatching: true,
  showHiddenLines: true,
});

document.body.innerHTML = svg;

Section cut

generateSection cuts vertically along the X or Z axis (use generateFloorPlan for horizontal cuts).

import { generateSection, exportToSVG } from '@ifc-lite/drawing-2d';

// Vertical section through plane x = 5
const drawing = await generateSection(meshes, 'x', 5, {
  includeHiddenLines: false,
  includeProjectionLines: true,
});

const svg = exportToSVG(drawing);

For arbitrary sections (custom plane, projection depth, scale), use Drawing2DGenerator + createSectionConfig directly:

import { Drawing2DGenerator, createSectionConfig } from '@ifc-lite/drawing-2d';

const generator = new Drawing2DGenerator();
await generator.initialize();

const config = createSectionConfig('y', 2.5, { projectionDepth: 5, scale: 50 });
const drawing = await generator.generate(meshes, config, {
  includeHiddenLines: true,
  includeMaterialHatching: true,
});

generator.dispose();

Graphic overrides

Apply named graphic presets (architectural, fire-safety, structural, MEP, monochrome) via the override engine:

import {
  createOverrideEngine,
  getBuiltInPreset,
  ifcTypeCriterion,
} from '@ifc-lite/drawing-2d';

// Use a built-in preset
const fireSafety = getBuiltInPreset('preset-fire-safety');
const engine = createOverrideEngine(fireSafety?.rules);

// Or define custom rules
const custom = createOverrideEngine([
  {
    id: 'highlight-walls',
    name: 'Highlight load-bearing walls',
    enabled: true,
    priority: 10,
    criteria: ifcTypeCriterion(['IfcWall', 'IfcWallStandardCase']),
    style: { strokeColor: '#d62828', strokeWidth: 0.7 },
  },
]);

// Resolve the style for an element
const result = engine.applyOverrides({
  expressId: 12345,
  ifcType: 'IfcWall',
  properties: { /* psets keyed by name */ },
});
console.log(result.style);

Built-in presets: preset-3d-colors (default), preset-architectural, preset-structural, preset-mep, preset-fire-safety, preset-monochrome. List them via BUILT_IN_PRESETS or look one up with getBuiltInPreset(id).

Drawing sheets

For presentation output, the package ships paper sizes, drawing frames, title blocks, scale bars, and north arrows as composable building blocks rather than a single one-shot helper. Bring in the pieces you need from the sheet module:

import {
  // Paper
  PAPER_SIZE_REGISTRY,
  getDefaultPaperSize,
  // Frames
  createFrame,
  renderFrame,           // returns { svgElements, innerBounds }
  // Title blocks
  createTitleBlock,
  renderTitleBlock,      // returns { svgElements, ... }
  DEFAULT_TITLE_BLOCK_FIELDS,
  // Scale bar / north arrow
  DEFAULT_SCALE_BAR,
  DEFAULT_NORTH_ARROW,
  renderScaleBar,
  renderNorthArrow,
} from '@ifc-lite/drawing-2d';

Each renderer returns SVG fragments that you wrap in your own <svg> document — see the 2D Drawings Guide for a worked sheet-composition example.

DXF reference underlays

Import an existing DXF drawing (site plan, survey, coordination set) as a reference layer beneath a generated floor plan. importDxf parses ASCII DXF — LINE, LWPOLYLINE/POLYLINE (with bulge arcs), CIRCLE, ARC, ELLIPSE, SPLINE, SOLID/TRACE, HATCH, TEXT/MTEXT, DIMENSION blocks, and INSERT/BLOCK references — into world-plan geometry (metres, +Y = north; DXF and IFC are both Z-up) with per-layer visibility and resolved ACI/true colours and lineweights. $INSUNITS drives the unit conversion; unitless files with large extents are assumed to be millimetres (with a warning).

import { importDxf, exportToSVG } from '@ifc-lite/drawing-2d';

const underlay = importDxf(dxfFileText, 'site-plan.dxf');
// underlay.layers[n].paths / .fills / .texts, underlay.bounds, underlay.warnings

// Composite beneath an exported floor plan:
const svg = exportToSVG(drawing, {
  underlays: [{
    underlay,
    placement: { offsetX: 0, offsetY: 0, rotationDeg: 0, scale: 1 },
    layerVisibility: { 'A-SITE': true },
    opacity: 0.8,
  }],
});

Unsupported entity types are counted in underlay.skipped rather than failing the import; parse problems (missing blocks, spline approximations, unknown units) surface in underlay.warnings.

API

See the 2D Drawings Guide and API Reference.

License

MPL-2.0