Translate/rotate: no particular algorithm, apart the way we convert the mouse clicks to a translation and rotation matrix maybe? (for this you can look at the ccGLWindow.cpp class - especially the mouseMoveEvent and mousePressEvent methods - but I'm not sure this is what you are looking for ;).
Unroll: once again, it's fairly simple maths here, apart maybe for the cone unrolling procedure. Anyway, you can see how it is implemented in the ccPointCloud.cpp class, unrollOnCylinder and unrollOnCone methods.
Projection: can you be more specific?
Daniel, CloudCompare admin