BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
U++ is a C++ cross-platform rapid application development suite focused on programmers' productivity without sacrificing runtime performance. Based on strictly deterministic design, it provides a viable alternative to garbage-collected platforms, even for business logic oriented problems.
SolarCalc is a program for estimating the solar radiation and electrical energy yield in a given site around the world. The software has been written in Qt and uses the most recent models of solar radiation conversion by PV effects. The software can take into account many aspects of solar systems such as detailed diffuse/beam correlation models, temperature effects, and shadowing effects. The system allows you to build a user-based archive of components, like solar panels and inverters. Many printing and exporting functions are available, as well as ready-to-use PDF report export.