[Mesa-dev] [PATCH] mesa: Loosen glBlitFramebuffer restrictions on depthstencil buffers (v2)

[Ian Romanick]

On 01/19/2012 12:12 PM, Christoph Bumiller wrote:
> On 19.01.2012 19:53, Ian Romanick wrote:
>> On 01/18/2012 12:31 PM, Chad Versace wrote:
>>> --- snip
>>>
>>> Supporting Z32 ->   Z32_FLOAT is a bad idea. So I've amended the patch
>>> to avoid that.
>>>
>>> --- end snip
>>>
>>>
>>> This loosens the format validation in glBlitFramebuffer. When blitting
>>> depth bits, don't require an exact match between the depth formats; only
>>> require that the two formats have the same number of depth bits and the
>>> same depth datatype (float vs uint). Ditto for stencil.
>>>
>>> Between S8_Z24 buffers, the EXT_framebuffer_blit spec allows
>>> glBlitFramebuffer to blit the depth and stencil bits separately. So I
>>> see
>>> no reason to prevent blitting the depth bits between X8_Z24 and
>>> S8_Z24 or
>>> the stencil bits between S8 and S8_Z24. However, we of course don't want
>>> to allow blitting from Z32 to Z32_FLOAT.
>>>
>
> So is it also allowed to blit from S8Z24 to Z24S8 ? Could we also allow
> to blit from RGBA8 to BGRA8 then, please ?

Based on the spec language that Brian quoted, that should already be 
allowed.  I'd swear that there was a piglit test that tries to blit from 
a RGBA8 to RGB10A2 FBO...

> That would fix my multisampling fail - all applications that use
> framebuffer_multisample try to blit resolve directly from an MS
> renderbuffer to the window system back buffer and that means I have to
> know somehow which ordering the window system chooses, which is rather
> inconvenient and made me hack-disable RGBA8 in the gallium driver, i.e.
> lie about what formats it supports.
>
> If I recall correctly, the NV blob does allow resolving between BGRA and
> RGBA.
>
>>> --------
>>>
>>> Fixes Piglit fbo/fbo-blit-d24s8 on Intel drivers with separate stencil
>>> enabled.
>>>
>>> The problem was that, on Intel drivers with separate stencil, the
>>> default
>>> framebuffer has separate depth and stencil buffers with formats
>>> X8_Z24 and
>>> S8. The test attempts to blit the depth bits from a S8_Z24 buffer
>>> into the
>>> default framebuffer.
>>>
>>> v2: Check that depth datatypes match in order prevent Z32 ->   Z32_FLOAT.
>>>
>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44665
>>> Note: This is a candidate for the 8.0 branch.
>>> CC: Brian Paul<brianp at vmware.com>
>>> CC: Kenneth Graunke<kenneth at whitecape.org>
>>> CC: Iam Romanick<idr at freedesktop.org>
>>
>> Reviewed-by: Ian Romanick<ian.d.romanick at intel.com>
>>
>>> Reported-by: Xunx Fang<xunx.fang at intel.com>
>>> Signed-off-by: Chad Versace<chad.versace at linux.intel.com>
>>> ---
>>>    src/mesa/main/fbobject.c |   13 ++++++++++---
>>>    1 files changed, 10 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c
>>> index 0524959..2b3ac2e 100644
>>> --- a/src/mesa/main/fbobject.c
>>> +++ b/src/mesa/main/fbobject.c
>>> @@ -2709,9 +2709,13 @@ _mesa_BlitFramebufferEXT(GLint srcX0, GLint
>>> srcY0, GLint srcX1, GLint srcY1,
>>>          if ((readRb == NULL) || (drawRb == NULL)) {
>>>         mask&= ~GL_STENCIL_BUFFER_BIT;
>>>          }
>>> -      else if (readRb->Format != drawRb->Format) {
>>> +      else if (_mesa_get_format_bits(readRb->Format,
>>> GL_STENCIL_BITS) !=
>>> +           _mesa_get_format_bits(drawRb->Format, GL_STENCIL_BITS)) {
>>> +     /* There is no need to check the stencil datatype here, because
>>> +      * there is only one: GL_UNSIGNED_INT.
>>> +      */
>>>             _mesa_error(ctx, GL_INVALID_OPERATION,
>>> -                     "glBlitFramebufferEXT(stencil buffer format
>>> mismatch)");
>>> +                     "glBlitFramebufferEXT(stencil buffer size
>>> mismatch)");
>>>             return;
>>>          }
>>>       }
>>> @@ -2731,7 +2735,10 @@ _mesa_BlitFramebufferEXT(GLint srcX0, GLint
>>> srcY0, GLint srcX1, GLint srcY1,
>>>          if ((readRb == NULL) || (drawRb == NULL)) {
>>>         mask&= ~GL_DEPTH_BUFFER_BIT;
>>>          }
>>> -      else if (readRb->Format != drawRb->Format) {
>>> +      else if ((_mesa_get_format_bits(readRb->Format, GL_DEPTH_BITS) !=
>>> +            _mesa_get_format_bits(drawRb->Format, GL_DEPTH_BITS)) ||
>>> +           (_mesa_get_format_datatype(readRb->Format) !=
>>> +        _mesa_get_format_datatype(drawRb->Format))) {
>>>             _mesa_error(ctx, GL_INVALID_OPERATION,
>>>                         "glBlitFramebufferEXT(depth buffer format
>>> mismatch)");
>>>             return;
>>
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