Lib2geom

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What is lib2geom?

lib2geom (2Geom in private life) was initially a library developed for Inkscape, but it can provide a robust computational geometry framework for any application. It is not a rendering library, instead concentrating on high level algorithms such as computing arc length.

Design Decisions

  • Small, algebraic objects (Point/Matrix) will be mutable, whereas large objects like a pathset will be immutable. <justification here>
  • We are using an original development method we've dubbed "Toy Driven Development". Under this process graphical toys are implemented which allow playing with the features of the library.

Quick Feature List

(not complete)

  • C++
  • Functional programming style.
  • Points
  • Efficient affine transformations
  • Rectangles
  • Convex Hulls
  • Bounded error
  • General purpose paths:
    • Exact elliptical arcs
    • Area
    • Centroid and bending moments
  • Path Locations:
    • Determination of special spots (e.g. maximum curvature)
    • Splitting
    • Point, tangent, curvature at location
    • Efficient arc length and inverse arc length
  • Path algebra:
    • Computations such as offset curves can be written with their mathematical definition and still get a bounded error, efficient curve. (preliminary trials indicate offset done this way out performs the method used in Inkscape)
  • Arbitrary distortion (with bounded error):
    • Mesh distorts
    • Computational distorts such as the GIMP's 'vortex' plugin
    • 3d mapping (perspective, flag, sphere)
  • Exact boolean ops (elliptic arcs remain elliptic arcs)
  • Efficient 2d database
  • Implicit function plotting
  • NURBs input and output
  • Tunable path simplification
  • PDoF constraint system for CAD/CAGD


Links

WorkingWith2GeomFAQ: real-life questions answered about using 2Geom in real code

lib2geom py2geom: Python bindings to 2geom. With this you can use the power of 2geom in Python scripts.

https://sourceforge.net/p/lib2geom/wiki: 2geom wiki site on SourceForge (obsolescent)

https://gitlab.com/inkscape/lib2geom/: Official source code for the project