There is a hidden issue, though, as many open-source C++ libraries commonly have LGPL license - pretty good for desktop, but might have legality issues in case of a Web application.

WebAssembly-based viewer may give some performance benefits and it is more friendly to C++ developers (but apparently - less friendly to JavaScript developers). The Web viewer itself relies on WebGL and normally can be based on any traditional JavaScript-based library like Three.js (or existing 3D Viewer on top), or may rely on C++-based engine (again, Open CASCADE Technology can be build as WebAssembly module). But in case of native CAD formats support (like CATIA and others) you will unlikely find any free open-source libraries. The converter may be based on Open CASCADE Technology, which is an open source framework, in case if STEP/IGES input file formats are enough (output could be your custom file format or glTF 2.0, for instance). The viewer might just display 3D model (in which case it is barely distinguishable from non-CAD viewers), or give many features like Shaded and Wireframe (not just mesh edges) modes, picking sub-parts, Clipping Boxes, clipping with capping, annotations, dimensions, explode view, HLR view, a bunch of them!Īlthough it is technically possible loading some small CAD models directly in the Browser, in general this task is expected to reside on server to improve user experience and give some protection to intellectual properties (of CAD models).

HTML+JavaScript code for displaying 3D model using WebGL, as well as GUI and application-specific logic. In simplest case, this might be just a file server providing 3D model in format like glTF. The complexity of 3D Viewer backend depends on functionality provided with it and ability of viewer to handle extra-large models. Server backend implementing business logic and backend for 3D viewer.This step might include model simplification in case if you have to deal with large models. Generation of Web-friendly triangulation-based 3D model.You might need a lot of Data Connectors in case if you need supporting wide range of CAD formats, or restrict functionality to import vendor-neutral formats like STEP. Conversion of CAD file into intermediate format.

CAD viewer solution for a WEB can be split into several pieces:

Free online cad viewer