[Mesa-dev] [PATCH 08/17] intle: Add an assert for glCopyTexSubImage() being called on MSAA buffers.

[Eric Anholt]

Chad Versace <chad.versace at linux.intel.com> writes:

> On 05/28/2013 01:54 PM, Eric Anholt wrote:
>> Marek Olšák <maraeo at gmail.com> writes:
>>
>>> CopyTexSubImage can be called on a multisample renderbuffer if the
>>> renderbuffer is part of the window-system framebuffer (i.e. comes from
>>> the visual).
>>>
>>> IIRC, the game Cogs uses it if both MSAA and Post Filters are enabled.
>>
>> Good to note; I hadn't thought about this.  This should be covered by
>> the blorp CTSI path, but at least we'll find out more obviously now if
>> that turns out to be false for some reason.
>
> --- -8<- ----
> static void
> intelCopyTexSubImage(struct gl_context *ctx, GLuint dims,
>                       struct gl_texture_image *texImage,
>                       GLint xoffset, GLint yoffset, GLint zoffset,
>                       struct gl_renderbuffer *rb,
>                       GLint x, GLint y,
>                       GLsizei width, GLsizei height)
> {
>     struct intel_context *intel = intel_context(ctx);
>     if (dims != 3) {
> #ifndef I915
>        /* Try BLORP first.  It can handle almost everything. */
>        if (brw_blorp_copytexsubimage(intel, rb, texImage, x, y,
>                                      xoffset, yoffset, width, height))
>           return;
> #endif
>
>        /* Next, try the BLT engine. */
>        if (intel_copy_texsubimage(intel,
>                                   intel_texture_image(texImage),
>                                   xoffset, yoffset,
>                                   intel_renderbuffer(rb), x, y, width, height))
>           return;
>     }
> --- ->8- ----
>
> If the read buffer is multi-sampled and brw_blorp_copytexsubimage fails for an
> unexpected reason, then the assertions fail. To avoid that disaster, I think
> the assertions should be replaced with `if (is_multisampled) return false`.

The code that gets called after that will also be a trainwreck in the
presence of multisampling.  You really want to assert at this point.
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