[Mesa-dev] [PATCH 4/7] main: rework the compatibility check of visuals in glXMakeCurrent

[Brian Paul]

On 02/25/2016 08:26 AM, Miklós Máté wrote:
> On 02/25/2016 02:37 AM, Brian Paul wrote:
>> On 02/24/2016 04:35 PM, Miklós Máté wrote:
>>> Now it follows the GLX 1.4 specification.
>>
>> Can you elaborate on that a bit?
> Section 2.1 of the GLX spec lists a few criteria for a context and a
> drawable to be compatible.
>
>>
>>
>>> This fixes post-processing in SW:KotOR.
>>>
>>> Signed-off-by: Miklós Máté <mtmkls at gmail.com>
>>> ---
>>>   src/mesa/main/context.c | 42
>>> ++++++++++++------------------------------
>>>   1 file changed, 12 insertions(+), 30 deletions(-)
>>>
>>> diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
>>> index 26eee28..6c16229 100644
>>> --- a/src/mesa/main/context.c
>>> +++ b/src/mesa/main/context.c
>>> @@ -1525,10 +1525,6 @@ _mesa_copy_context( const struct gl_context
>>> *src, struct gl_context *dst,
>>>    * Check if the given context can render into the given framebuffer
>>>    * by checking visual attributes.
>>>    *
>>> - * Most of these tests could go away because Mesa is now pretty
>>> flexible
>>> - * in terms of mixing rendering contexts with framebuffers.  As long
>>> - * as RGB vs. CI mode agree, we're probably good.
>>> - *
>>>    * \return GL_TRUE if compatible, GL_FALSE otherwise.
>>>    */
>>>   static GLboolean
>>> @@ -1541,32 +1537,18 @@ check_compatible(const struct gl_context *ctx,
>>>      if (buffer == _mesa_get_incomplete_framebuffer())
>>>         return GL_TRUE;
>>>
>>> -#if 0
>>> -   /* disabling this fixes the fgl_glxgears pbuffer demo */
>>> -   if (ctxvis->doubleBufferMode && !bufvis->doubleBufferMode)
>>> -      return GL_FALSE;
>>> -#endif
>>> -   if (ctxvis->stereoMode && !bufvis->stereoMode)
>>> -      return GL_FALSE;
>>> -   if (ctxvis->haveAccumBuffer && !bufvis->haveAccumBuffer)
>>> -      return GL_FALSE;
>>> -   if (ctxvis->haveDepthBuffer && !bufvis->haveDepthBuffer)
>>> -      return GL_FALSE;
>>> -   if (ctxvis->haveStencilBuffer && !bufvis->haveStencilBuffer)
>>> -      return GL_FALSE;
>>> -   if (ctxvis->redMask && ctxvis->redMask != bufvis->redMask)
>>> -      return GL_FALSE;
>>> -   if (ctxvis->greenMask && ctxvis->greenMask != bufvis->greenMask)
>>> -      return GL_FALSE;
>>> -   if (ctxvis->blueMask && ctxvis->blueMask != bufvis->blueMask)
>>> -      return GL_FALSE;
>>> -#if 0
>>> -   /* disabled (see bug 11161) */
>>> -   if (ctxvis->depthBits && ctxvis->depthBits != bufvis->depthBits)
>>> -      return GL_FALSE;
>>> -#endif
>>> -   if (ctxvis->stencilBits && ctxvis->stencilBits !=
>>> bufvis->stencilBits)
>>> -      return GL_FALSE;
>>> +#define check_component(foo)           \
>>> +   if (ctxvis->foo && bufvis->foo &&   \
>>> +       ctxvis->foo != bufvis->foo)     \
>>> +      return GL_FALSE
>>> +
>>> +   check_component(redMask);
>>> +   check_component(greenMask);
>>> +   check_component(blueMask);
>>> +   check_component(depthBits);
>>> +   check_component(stencilBits);
>>> +
>>> +#undef check_component
>>
>> IIRC, Ian had some comments on this so he should re-review.  But since
>> Mesa doesn't actually used the red/green/blueMask fields (AFAIK), I'm
>> not sure what those checks are good for.
> Yes, my original intention was to remove this function entirely, but Ian
> convinced me that GLX mandates at least these checks.

I wonder if those checks could be moved into the GLX code.

For Windows, the wglMakeCurrent docs say "The hdc parameter must refer 
to a drawing surface supported by OpenGL. It need not be the same hdc 
that was passed to wglCreateContext when hglrc was created, but it must 
be on the same device and have the same pixel format."  We check for 
that in our stw_make_current() in the WGL code.

-Brian