Graphics processing systems

When rendering plural views of the same scene in a graphics processing system, (43), e.g. for stereoscopic rendering, the graphics processing operation (e.g. shading) is configured so that, if possible, rather than executing the program separately for each view that is being rendered, a single program is executed once for all the views. The program that is executed is configured to, for view dependent operations, perform the respective operation separately for each view (48), so as to derive an appropriate value (e.g. vertex shaded output attribute) for each view, but is also configured to, for operations that are not dependent upon the view being rendered, perform those operations only once for the set of views and to provide only a single output value for each work item (e.g. vertex) in question for the set of views (49).