--export-png

--export-png renders a PNG preview image for one or all plates in a loaded 3MF. Pass 0 to render every plate in the file, or a positive integer to render only that plate by its 1-based index. The flag is mutually exclusive with other CLI actions: supplying any second action alongside it is rejected with an invalid-parameters error before anything is written.

The render is done through the same OpenGL thumbnail path used to generate the preview images stored inside a 3MF. The camera is always orthographic. The angle is controlled by the companion flag --camera-view, whose integer value selects the named camera angle: 0=Iso (the default), 1=Top_Front, 2=Left, 3=Right, 10=Iso_1 (Iso rotated 90° clockwise), 11=Iso_2 (180°), 12=Iso_3 (270°). Each output file is 512×512 pixels, named plate_{N}_{angle}.png where N is the 1-based plate number and {angle} is the integer value passed to --camera-view. If --outputdir is supplied, files land in that directory; otherwise they are written to the current working directory.

OpenGL must initialise successfully for any PNG to be produced. On Linux the build uses the OSMesa off-screen rendering API, so rendering can succeed in a fully headless environment with no display or virtual framebuffer. On other platforms a real or virtual display is required. When initialisation fails the render block is silently skipped: no PNGs are written, no non-zero exit code is returned, and the process exits normally; the failure is recorded in the internal debug log.