OpenGL 4.5 3D engine - modern/advanced and easy to use.
A 3D engine built in C# using OpenTK - it makes use of modern rendering techniques/shaders. Still in very active development.
Professional graphics for open-source games.
.Render is an open-source rendering engine for SlimDX and MonoGame that aims to produce realistic images in real-time. It's nowhere near a production release at the moment, however, so don't put it in your games quite yet! In the meantime, if you're looking for a rendering engine right now, you might like to try Bart Wronski's C#/.NET graphics framework at http://bartwronski.com/2014/04/10/c-net-graphics-framework/ .
The GEM 3D engine is a portable, free, open source, easy to use, software development kit which allows you to build high performance 3D graphics applications such as games.
NLight is a framework for implementing and testing photo realistic rendering algorithms developed in C# with extensibility in mind.
A toolkit for Rendering high quality computer graphics and Animation Movies by building simple rendering cluster
An open source 3D engine designed specifically to use ObjectiveC.
Unified Environment Handler that sits on OpenGLUT's head, processing collisions, friction, etc, as well as including extended lighting, shading, and anti-aliasing not native to OpenGLUT.
crossplatform multithreaded object-oriented render and audio engine
SH-Engine - crossplatform multithreaded object-oriented render and audio engine. Based on OpenGL 3. Support for Windows and Linux. Contains 2D-graphics, 3D-scene and sound.
An Easy Graphics Library. Full vertex, geometry, and pixel shader support. Libraries include vector graphics, scene graph, and linear algebra. All .NET languages (C#, IronPython, C++/CLI, etc). Linux and Windows (OpenGL and DirectX 10)
Simple & Extensible DirectX 3D Graphics & Game Programming Architecture for Lightweight Game Developing
Infinite Dream is an ambitious project to implement a paradigm-shifting set of software and related documentation, including a distributed network, a user interface and application programming interface, culminating in a complete operating system.
We provide an easy to use object-oriented framework for realtime raytracing. The core is implemented via OpenCL and though running platform independent on NVIDIA and ATI graphics cards.