On 01/13/2015 02:34 PM, Mason, Michael W wrote:
>> -----Original Message-----
>> From: Versace, Chad
>> Sent: Tuesday, January 13, 2015 10:47 AM
>> To: Mason, Michael W; mesa-dev@lists.freedesktop.org
>> Subject: Re: [Mesa-dev] [PATCH] mesa: Fix render buffer initial internal
>> format type
>>
>> On 01/09/2015 05:21 PM, michael.w.ma...@intel.com wrote:
>>> From: Mike Mason <michael.w.ma...@intel.com>
>>>
>>> Changes the initial internal format of a render buffer to GL_RGBA4.
>>> This fixes a failure in the following DrawElements test:
>>>
>>> dEQP-GLES3.functional.state_query.rbo.renderbuffer_internal_format
>>> ---
>>> src/mesa/main/renderbuffer.c | 6 +++++-
>>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/src/mesa/main/renderbuffer.c
>>> b/src/mesa/main/renderbuffer.c index 0bc7f2b..b339491 100644
>>> --- a/src/mesa/main/renderbuffer.c
>>> +++ b/src/mesa/main/renderbuffer.c
>>> @@ -53,7 +53,11 @@ _mesa_init_renderbuffer(struct gl_renderbuffer *rb,
>>> GLuint name)
>>> rb->Width = 0;
>>> rb->Height = 0;
>>> rb->Depth = 0;
>>> - rb->InternalFormat = GL_RGBA;
>>> + /* Default internal format should be GL_RGBA4, per page 258,
>>> + * table 6.15 of the GLES 3.0.4 spec. Same default is expected
>>> + * in all OpenGL specs that support BindRenderbuffer().
>>> + */
>>> + rb->InternalFormat = GL_RGBA4;
>>> rb->Format = MESA_FORMAT_NONE;
>>> }
>>>
>>>
>> The patch needs to choose the initial internalformat based on
>> the context API. Table 6.26 in the GL 3.3 Core spec says the initial
>> renderbuffer internalformat is GL_RGBA. Table 6.15 of
>> the GLES 3.0 spec says GL_RGBA4.
>>
>> I think this is the correct logic:
>>
>> if (_mesa_is_desktop_gl(ctx)) {
>> rb->InternalFormat = GL_RGBA;
>> } else {
>> rb->InternalFormat = GL_RGBA4;
>> }
>
> "ctx" isn't available in _mesa_init_renderbuffer (where this code resides)
> and GET_CURRENT_CONTEXT(ctx) gives nil for ctx. Is there any other way to
> get a pointer to the gl_context?
Drivers call _mesa_init_renderbuffer for 3 reasons, as far as I can tell:
1. To initialize Mesa's gl_renderbuffer structure in response to a real GL
renderbuffer object created with glGenRenderbuffers.
2. To initialize a driver-private renderbuffer in response of the user
attaching a texture to a framebuffer object, such as with
glFramebufferTexture2D.
3. To initialize a driver-private renderbuffer that serves as backing
storage
for window system surfaces, such as eglCreateWindowSurface or a GLX
Window.
Only in case 1 will the user have a handle to the renderbuffer object and be
able to call glGetRenderbufferParameteriv on it. In case 2, there is always a
context present (I think...), but the driver will immediately overwrite the
value of rb->InternalFormat anyway, so it doesn't really matter what value
_mesa_init_renderbuffer chooses. In case 3, there may or may not be a context
present, but again the internalformat doesn't matter because the driver will
immediately overwrite it.
From that follows:
- If a context is current, we are in case 1 or 2. Case 1 is the more
restrictive
case. It requires that we select the internalformat based on the
context's API.
- If a context is not current, we are in case 3, or possibly case 2 if I
don't
fully understand the problem space. Either way, in neither case 2 nor 3
does
the value of internalformat matter, so we should just continue to
initialize
it to GL_RGBA as we have always done.
>> Please add both spec references in your patch.
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