DXF, SVG, STEP and BREP converter

Each of these formats has its place in a workflow. DXF is the exchange format of 2D CAD programs and the usual input of laser, waterjet and plasma cutting software. SVG is the format of drawing programs such as Inkscape, of vinyl and laser cutters, and of the web. STEP carries geometry between CAD, CAM and simulation programs, and BREP is the native format of OpenCASCADE, which programs built on it, such as FreeCAD and Gmsh, read. PDF and PNG are for printing and for documents. The converters take a drawing from one of these formats into another without a CAD program, many files at once and at true size.

Reading

The format of each file is found from its content, so a file with an unusual or missing extension is read as well. planex2d reads DXF files with ezdxf, SVG files with svgelements, and STEP and BREP files with its own readers. Lines, arcs and circles stay lines, arcs and circles, and splines and ellipses stay exact curves. Each DXF layer and each SVG group is read on its own, so that a center line does not cut the outline it crosses. Within a layer, lines that cross are split where they cross, and a stretch drawn twice is kept once.

Faces and curves

A closed outline becomes a face, with the outlines inside it as its holes, and an open line stays a curve. STEP and BREP files hold the faces as planar surfaces and the curves as edges. DXF and SVG files hold the outlines as lines, arcs, circles and splines. With Fill faces, DXF adds each face as a hatch and SVG as a filled path.

Units

The drawing keeps its size. A file that names its unit is read in it, and the output counts in the unit you pick. DXF, SVG and STEP files name the unit in the file. BREP names none and simply holds its numbers in the unit you pick. A BREP file, and a DXF file whose header names no unit, is taken as millimeters. An SVG file without a unit counts in CSS pixels of 1/96 inch, as the SVG standard defines them.

PDF and PNG

A PDF shows the drawing in black at true size, on a page 10 mm larger than the drawing on every side, so that printed at 100 % it matches the part. A PNG is the same picture on white, 2000 pixels along its longer side. The unit setting does not apply to either.

Layers and colors

Each edge keeps its layer and its color. DXF writes them as the layer and its true color, and SVG as a labeled group, which Inkscape shows as a layer, with the stroke color. STEP writes them as the names and colors of its edges and faces. BREP keeps no names or colors.

1. Load

   The page loads Python and planex2d into this tab. Your browser keeps both in its cache, so later visits start faster.

2. Read

   The browser reads the files you add from your disk into memory and unpacks a zip in the tab. No request carries a file to a server.

3. Convert

   planex2d finds each file's format from its content, reads it into exact geometry and turns its closed outlines into faces.

4. Write

   Every file is written in the format you pick. One file is saved as it is, several as one zip, each named after the file it came from.

Supported files

Run it in Python

Everything the converters do is available in the library. Install it and see Files in the docs for every reader and writer. The example reads the outline layer of a DXF file, without its center lines, and writes the part as STEP and SVG in millimeters.

$ pip install planex2d

import planex as px

bracket = px.Face(px.FromDXF("mounting-bracket.dxf", layers=["contour"]))
bracket.WriteStep("mounting-bracket.step", unit=px.mm)
bracket.WriteSVG("mounting-bracket.svg", unit=px.mm)

Privacy

Limits

• This tool reads and writes planar STEP and BREP files only: each part lies in one plane.
• SVG has no exact form for rational splines or splines above degree 3. planex2d writes them as their arc approximation and says so below the file list.
• Text, dimensions, hatches and images are not read; the converters carry the geometry only.
• Gaps, open contours and tiny edges stay as they are. The contour checker finds and repairs them.
• In the browser, planex2d runs in one thread, so large drawings take longer than in Python on your machine.
• A file that fails? Open an issue on GitHub and attach the file if you can.