On 01/13/2015 06:09 PM, Chad Versace wrote:
Brian and Ian, me and Michael have a Mesa TLS question at the message's bottom.
On 01/13/2015 04:41 PM, Mason, Michael W wrote:
-----Original Message-----
From: Versace, Chad
Sent: Tuesday, January 13, 2015 3:42 PM
To: Mason, Michael W; mesa-dev@lists.freedesktop.org
Subject: Re: [Mesa-dev] [PATCH] mesa: Fix render buffer initial internal format
type
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.
So would something like this be safe? Is ctx guaranteed to be either nil or a
pointer to a valid context?
GET_CURRENT_CONTEXT(ctx);
if (ctx && _mesa_is_gles3(ctx)) {
rb->InternalFormat = GL_RGBA4;
} else {
rb->InternalFormat = GL_RGBA;
}
Brian and Ian, _mesa_init_renderbuffer() sometimes gets called with a current
context and
sometimes not, because it's used to initialize winsys renderbuffers. So me and
Michael
have arrived at this question:
If no context is current, does Mesa guarantee that GET_CURRENT_CONTEXT(ctx)
sets ctx = NULL?
That's the intention and I've never seen otherwise.
-Brian
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