Box is a language specifically designed to make vector graphics easy plus a integrated development environment which facilitates the use of the language by interactively showing the graphical output. Box combines the convenience of drawing figures with the mouse with the convenience of describing them with a language tailored for vector graphics.
SVG Graphics Editor written in Java
A powerful C++ class library for image manipulation
ImageStone is a powerful C++ class library for image manipulation. Its features include load, save, display, transformation, and nearly 100 special image effects. It can be used cross platform (includes Windows, Linux, Mac), and especially under windows it can be used as a DIB wrapper class.
Skencil is a vector drawing program. It's written almost completely in python for flexibilty with some modules written in C for speed.
A Java package to read and manipulate graphs in the GXL (Graph eXchange Language) format, as well as providing a GXL graph editor. Note from admin: This project is discontinued, send me a message if you want to take over.
GoGraph is a tutorial software giving informatics students an easy, interactive and ergonomic way to learn and exercise the graph theory. It is based on JGraph, an open-source graph component for Java.
A UML class diagram editor written in C++ using Tcl/Tk for the GUI portion. Designed to be easy to maintain and extend.
PLOT_PSXPS provides a set of graphic functions that allows the generation of PostScript files (and runtime viewing with X) from C/C++ programs. A page can contain points, lines, arcs, ellipses, circles, boxes, text, included EPS files and a lot more.
Splines library is (currently) a Windows DLL for generating a variety of spline curves. The code is mostly vanilla C code.
A tool for generating animated images of tweened color blends based on bezier surface patches where the height of the surface patch represents the color value. Three patches are used (R,G,B) to make up each patch. See website for web start application.
A library of 3-D tools for vector algebra. Already in wide use for 3 decades in crystallographic applications.