Dion Moult a34c36d22e ifcviewer: same-frame HiZ occlusion cull on GPU (step 3d)
Two-phase compute-cull dispatch when IFC_GPU_CULL=1:

  Phase 1  frustum + contribution + LOD, no HiZ  → survivors
  Depth    render survivors depth-only into half-viewport FBO
  Build    GPU compute max-reduce depth → R32F mip pyramid
  Phase 2  same cull + HiZ test                  → final survivors
  Color    render final survivors

The compact shader's new hizOccluded() projects 8 AABB corners to
screen space, picks the mip level where the covered rect fits in ≤2×2
texels, and rejects when the AABB's near-depth exceeds the pyramid's
max depth.

New GPU resources (per-window):
  hiz_gpu_fbo_ / hiz_gpu_depth_tex_  — depth-only FBO at half viewport
  hiz_gpu_pyramid_tex_                — R32F mipmapped pyramid
  hiz_gpu_copy_prog_                  — compute: depth → pyramid L0
  hiz_gpu_reduce_prog_                — compute: max-reduce L(n-1)→L(n)
  hiz_gpu_depth_prog_                 — vertex + trivial fragment

On a dense 18-model BIM dataset:
  survivors:  140k → 65k  (HiZ rejects ~50%)
  triangles:  22M  → 13M
  gpu_cull:   0.06ms → 22.5ms  (depth pre-pass CP overhead)

The depth pre-pass suffers the same empty-sub-draws CP overhead as the
color pass (690k commands, most with instanceCount=0).  Once MDI
compaction lands, both passes will be fast.  For now, net FPS is flat
(savings on color ≈ cost of depth pre-pass).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-04-23 21:32:24 +10:00
2026-04-23 10:58:57 +02:00
2025-12-19 18:53:14 +05:00
2026-04-23 21:32:24 +10:00
2026-04-19 10:35:04 +02:00
2026-01-26 17:10:03 +05:00
2026-04-21 21:48:15 +02:00
2026-04-10 17:29:46 +05:00
2023-09-14 09:29:20 +02:00
2026-02-18 09:09:46 +11:00
2025-08-28 20:05:45 +02:00
2025-08-28 20:05:45 +02:00
2026-04-13 19:38:25 +05:00
2026-04-13 19:40:25 +05:00

IfcOpenShell

IfcOpenShell is an open source (LGPL) software library for working with Industry Foundation Classes (IFC). Complete parsing support is provided for IFC2x3 TC1, IFC4 Add2 TC1, IFC4x1, IFC4x2, and IFC4x3 Add2. Extensive geometric support is implemented for the IFC releases IFC2x3 TC1 and IFC4 Add2 TC1. Extending with support for arbitrary IFC schemas is possible at compile-time when using C++ and at run-time when using Python.

In addition to a C++ and Python API, IfcOpenShell comes with an ecosystem of tools, notably including IfcConvert (an application to convert IFC models to other formats), Bonsai (an add-on to Blender providing a graphical IFC authoring platform), and many other libraries, CLI apps, and more. Support is also provided for auxiliary standards such as BCF and IDS.

For more information, see:

Development is sponsored through your generous donations!

Open Collective Contributors

Contents

Name Description License Service
bcf Library to read and write BCF-XML and query OpenCDE BCF-API modules LGPL-3.0-or-later PyPI Anaconda-Server Badge
bonsai Add-on to Blender providing a graphical native IFC authoring platform GPL-3.0-or-later Official GitHub Unstable Chocolatey
bsdd Library to query the bSDD API LGPL-3.0-or-later PyPI
ifc2ca Utility to convert IFC structural analysis models to Code_Aster LGPL-3.0-or-later
ifc4d Convert to and from IFC and project management software LGPL-3.0-or-later PyPI
ifc5d Report and optimise cost information from IFC LGPL-3.0-or-later PyPI
ifcbimtester Wrapper for Gherkin based unit testing for IFC models LGPL-3.0-or-later
ifcblender Historic Blender IFC import add-on LGPL-3.0-or-later*
ifccityjson Convert CityJSON to IFC LGPL-3.0-or-later PyPI
ifcclash Clash detection library and CLI app LGPL-3.0-or-later PyPI
ifcconvert CLI app to convert IFC to many other formats LGPL-3.0-or-later* Official GitHub
ifccsv Library and CLI app to export and import schedules from IFC LGPL-3.0-or-later PyPI
ifcdiff Compare changes between IFC models LGPL-3.0-or-later PyPI
ifcedit CLI wrapper for ifcopenshell.api IFC model mutation functions LGPL-3.0-or-later PyPI
ifcfm Extract IFC data for FM handover requirements LGPL-3.0-or-later PyPI
ifcmax Historic extension for IFC support in 3DS Max LGPL-3.0-or-later* Official
ifcmcp MCP server for querying and editing IFC building models LGPL-3.0-or-later PyPI
ifcopenshell-python Python library for IFC manipulation LGPL-3.0-or-later* Official GitHub PyPI Anaconda Anaconda Docker AUR AUR Unstable Pyodide WASM Wheels tag
ifcpatch Utility to run pre-packaged scripts to manipulate IFCs LGPL-3.0-or-later PyPI
ifcquery CLI tool for querying and inspecting IFC building models LGPL-3.0-or-later PyPI
ifcsverchok Blender Add-on for visual node programming with IFC GPL-3.0-or-later GitHub
ifctester Library, CLI and webapp for IDS model auditing LGPL-3.0-or-later PyPI

The IfcOpenShell C++ codebase is split into multiple interal libraries:

Name Description License
ifcgeom Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcgeom_schema_agnostic Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcgeomserver Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcjni Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcparse Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcwrap Internal library for IfcOpenShell LGPL-3.0-or-later*
qtviewer Internal library for IfcOpenShell LGPL-3.0-or-later*
serializers Internal library for IfcOpenShell LGPL-3.0-or-later*
S
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C 3.9%
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