[SOLVED]GLSL can I get Inverse Projection Matrix in quad?

how Can I get Inverse Projection Matrix in quad pass shader? I want to use GBuffers, also for world position should i create render-target?

I just wrote my own for a quad shader.
PS:
uniform mat4 cInvProj;

cam->GetProjection(false).Inverse(); // in this implementation, apiSpecific = false

Thank you, your code was very useful , and my main problem was I should have set name on parameter in xml.