Open Source Solid Modeling CAD
BRL-CAD is a powerful cross-platform constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing for rendering & geometric analyses, network distributed framebuffer support, image & signal-processing tools.
A fast and lean render engine with multiple renderbackends
TacitPixel is a scalable C++ framework for building application prototypes for interactive collaborative VR/AR applications. It provides a number of features that make prototyping fast and portable. TacitPixel is the successor of the TAP and Twisted Pair engines.