[Mesa-dev] [PATCH 1/4] gallium: Add support for multiple viewports

[Marek Olšák]

1) I prefer this interface instead:

void (*set_scissor_states)( struct pipe_context *,
                               unsigned start_slot, unsigned count,
                               const struct pipe_scissor_state * );

void (*set_viewport_states)( struct pipe_context *,
                                unsigned start_slot, unsigned count,
                                const struct pipe_viewport_state *);

Both function should allow updating only a subset of all viewports and
scissors (from start_slot to start_slot+count-1). This is especially
important for meta ops (u_gen_mipmap, etc.), which need to update only
the first viewport (and no scissor), leaving the other viewports
unchanged. This idea is not new: the vertex buffer and compute sampler
functions have the start_slot parameter too.


2) What does cso_context need to keep a copy of all viewports for? All
meta ops need only one viewport, just as they need only one vertex
buffer and one constant buffer (and cso_context doesn't really allow
meta ops to use more than that). For example, see how the cso_context
interface for saving and restoring the constant buffer slot 0 looks
like. It's preferable to use the same mechanism unless there is a need
to have the save and restore functionality for all slots.


Marek



On Thu, May 23, 2013 at 10:33 PM, Zack Rusin <zackr at vmware.com> wrote:
> Gallium supported only a single viewport/scissor combination. This
> commit changes the interface to allow us to add support for multiple
> viewports/scissors.
>
> Signed-off-by: Zack Rusin <zackr at vmware.com>