I would like to perform projective texturing on map by using the virtualProgram.
Since I have several nodes (aircraft models) that project an image on the terrain and i am using the same virtual program how is multiple texture units handled using the same virtual program or Do i have to manage it by myself (since the same virtual program from several nodes is performed on the same map node).
What have you done so far? Do you have it working with one texture? If so, expanding to work with multiple projected textures is no different than you would do in a normal Program. You calculate the projective texture coordinates for each one, and then sample each one in the fragment shader and combine them however you like.