Rajawali supports simple collision detection using bounding boxes and bounding spheres. The Geometry3D class contains two methods that can be used to retrieve the bounding volumes:

// -- myObject is of type BaseObject3D
// -- get the bounding box

IBoundingVolume boundingBox = myObject.getGeometry().getBoundingBox();

// -- or get the bounding sphere

IBoundingVolume boundingSphere = myObject.getGeometry().getBoundingSphere();

Both the BoundingBox and BoundingSphere classes have a transform() method that takes the current model’s model matrix as the only parameter. This is needed to translate, rotate and scale the bounding volume.

boundingBox.transform(myObject.getModelMatrix());

Once the bounding volume has been transformed we can check if it intersects with another bounding volume (of the same kind):

boolean intersects = boundingBox.intersectsWith(otherBoundingBox);
if(intersects)
     // -- collision!
else
    // -- no collision 

The source code can be found here:

RajawaliCollisionDetectionActivity.java

RajawaliCollisionDetectionRenderer.java