GLSL + GrabPass examples

Does anyone have an example of using GLSL together with GrabPass? The example in the Unity docs is decidedly unhelpful.

Exactly. The shader in the documentation doesn’t work at all. It keeps telling me that “no subshaders can run on this graphics card”.

Is the GrabPass-feature limited to Unity Pro? If so it would be VERY helpful to indicate so in the documentation. And, of course, the errormessage would have to be corrected too!