63 lines
4.4 KiB
Markdown
63 lines
4.4 KiB
Markdown
# Export the current view as DXF
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Choose **File → Export Current View as DXF…**, choose whether to omit hidden edges or
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export them as dashed lines, set **Curve tolerance**, then choose **Export DXF…** and a
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destination. Both settings are remembered. The Japanese menu is
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**ファイル → 現在の表示をDXFでエクスポート…**.
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On desktop, the export runs on a background worker while the window continues repainting
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and responding to its title-bar controls. A progress card shows mesh preparation, surface
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preparation, projection, hidden-line removal and writing, with a count and progress bar for
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the current stage. **Cancel** stops at the next mesh or traversal checkpoint; a single
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meshing call or sort may need to finish first. The model waits during the export and remains
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unchanged on success, failure and cancellation. Individual control-channel
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`file.export_view_dxf` commands use the same worker.
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The browser's export still runs synchronously on its single thread.
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An export replaces its destination atomically only after the complete drawing is ready.
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Cancellation that takes effect before the final write preserves any previous file. Once
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that atomic write starts, it finishes; a late Cancel reports the completed save.
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The drawing uses the camera when Export is pressed, including roll, the world's up axis
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and perspective. Only shown bodies are exported, at their current component/occurrence
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placements. Hidden bodies neither draw nor hide other bodies. The complete projected
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geometry is exported, including geometry beyond the viewport's edges. Grid, sketches,
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dimensions, selection highlights and other overlays are excluded. Turn off section analysis
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before exporting.
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Coordinates are 2D, Z=0, in millimetres. Orthographic views retain 1:1 dimensions in the
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view plane. Perspective views retain foreshortening, projected onto the plane through the
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camera target; they are intended for illustrations rather than dimensioned fabrication.
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Curves and curved silhouettes are approximated with straight segments at a default
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model-space chord tolerance of 0.01 mm. The setting accepts 0.0001–1 mm; smaller values
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produce finer curves and generally need more time and memory. This is not an exact analytic
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curve export or a tolerance guarantee for the original imported surfaces.
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The AutoCAD 2000 ASCII DXF contains `VISIBLE` (continuous) and, when requested, `HIDDEN`
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(2 mm dashes / 1 mm gaps) layers. Hidden curves use connected `LWPOLYLINE` entities with
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continuous linetype generation so the pattern does not restart on each chord. The pattern
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is embedded in the file. The polyline flags follow the
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[Autodesk DXF reference](https://help.autodesk.com/cloudhelp/2017/ENU/AutoCAD-DXF/files/GUID-748FC305-F3F2-4F74-825A-61F04D757A50.htm).
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Edges are split where another surface occludes them, including partial occlusion by another
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body. Hidden edges are never included in omit mode. Triangle diagonals and smooth seams
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are excluded; curved-body silhouettes are included. Very complex drawings fail with an
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error rather than returning an incomplete export. If geometry crosses the perspective
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camera's eye plane, zoom out before exporting.
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Repeated component placements share their export mesh and triangle hierarchy. Each placement
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keeps its own edge choices, position and orientation; no bodies are fused or omitted to reduce
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the workload. A hierarchy over placed parts rejects unrelated occluders before searching a
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part's triangles. Already hidden intervals are skipped, and a fully hidden line stops searching.
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Desktop mesh preparation and independent line queries use at most eight computation workers;
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the browser runs serially. Export memory, candidate lines, output lines and total occlusion
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work remain bounded, and exceeding a budget returns an error without writing a partial drawing.
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Programmatic callers use `file.export_view_dxf` with `camera: Camera`, `hidden: "omit"` or
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`"dashed"`, optional `tolerance` (0.0001–1 mm) and optional `path`. Without `path`, the
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command returns the DXF text. The command does not modify the design or its undo history.
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The result also includes `stats`: placed body and shared mesh counts, source triangle count,
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retained mesh bytes, worker limit, candidate segment count, occlusion work, and preparation,
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projection and occlusion times in milliseconds. These timings exclude STEP import and DXF
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serialization; the worker limit is a maximum, not a claim that every worker was busy.
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