On 21 July 2012 17:36, Chad Versace <chad.vers...@linux.intel.com> wrote:
> Actually, this patch forces an automatic downsample during
> intel_miptree_map. And this should occur only due to glReadPixels.
>
> CC: Eric Anholt <e...@anholt.net>
> CC: Paul Berry <stereotype...@gmail.com>
> Signed-off-by: Chad Versace <chad.vers...@linux.intel.com>
> ---
> src/mesa/drivers/dri/intel/intel_mipmap_tree.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
> b/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
> index c4496ea..26002c2 100644
> --- a/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
> +++ b/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
> @@ -1339,6 +1339,15 @@ intel_miptree_map(struct intel_context *intel,
> {
> struct intel_miptree_map *map;
>
> + if (mt->num_samples > 0 && (mode & GL_MAP_WRITE_BIT)) {
> + /* We choose not support swrast on multisample buffers because
> + * it would require an upsample on unmap. As of 2012-07-20, this
> + * warning occurs only on glDrawPixels(GL_STENCIL_INDEX).
> + */
> + _mesa_warning(&intel->ctx, "unsupported fallback to software "
> + "rasterization on a multisample buffer");
> + }
> +
> map = calloc(1, sizeof(struct intel_miptree_map));
> if (!map){
> *out_ptr = NULL;
> @@ -1354,6 +1363,7 @@ intel_miptree_map(struct intel_context *intel,
> map->w = w;
> map->h = h;
>
> + intel_miptree_downsample(intel, mt);
> intel_miptree_slice_resolve_depth(intel, mt, level, slice);
> if (map->mode & GL_MAP_WRITE_BIT) {
> intel_miptree_slice_set_needs_hiz_resolve(mt, level, slice);
> --
> 1.7.11.2
>
>
It seems to me that we also need to write some code to ensure that
glReadPixels() reads from mt->singlesample_mt rather than mt. (Otherwise,
on Gen6, glReadPixels() will see something awful, and on Gen7,
glReadPixels() will read from the first slice of the UMS/CMS buffer, which
will look ok like no multisampled occurred). Or am I missing something?
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