Most popular open-source, free, well-documented game engine for research application

Question

My company is getting ready to propose a stroke and brain-injury rehabilitation tool and we need to know what free, open-source, and well-documented game engine are out there.

• We will be constructing a 3D environment.
• We will need to have good control over characters fine motions (for instance even finger motions).
• We need a good physics engine including collision detection and inverse kinematics if possible.
• It would be very useful if there are already some hooks in the code for providing haptic feedback, but that's not necessary.
• Graphics do not need to be phenomenal.
• It must be relatively easy to throw together a proof of concept.

I'm predisposed toward Jake2 because Java's dead easy to program in, but I need more options to consider from you folks who have experience.

Answer 1

I would consider looking at ioquake3 which is an opensource port of Quake 3. Also, I would like to point out the excellent Delta3d which is a DoD funded and developed opensource simulation engine.

Notre Dame evaluates several engines in the paper A Survey of Collaborative Virtual Environment Technologies. I would think that this would be best starting point as you will be able to access alot of existing knowledge on engines when applied to virtual environments.

Answer 2

Consider between

• Ogre3d,
• Irrlicht,
• Panda3d,
• Torque3d

I think Delta3d is the best.

Their code easy to learn and it applying many rules of C++ Design. I finished read Scott Meyers Effective C++, More Effective C++, and I really like the way Delta3d code implemented.

The Cons: Delta3d community is small, but it really is best open source game engine.

Answer 3

Consider OGRE.

Update: It's a very solid and powerful game engine, but something funky is going on on their website, I can't open most of the pages. Don't judge based on that. Give it a try.

Answer 4

It's probably worth looking at jMonkeyEngine, especially if you already have existing Java experience / investments.

I was pretty impressed by how easy it was to get a 3D environment up and running.

There is also supposedly good jBullet physics integration - although I haven't tried that yet.

Answer 5

You may want to take a look at Irrlicht. It is free and open-source and has the ability to run on multiple platforms using your choice of graphics API (DirectX, OpenGL, etc.). It's written in C++ and has excellent documentation, in addition to an active community. Although it doesn't have a built in physics engine, it's relatively easy to tie in any external engine like Havok, Bullet, etc.