[Mesa-dev] [PATCH 17/23] readpix: for implentation format/type, ignore int vs. non-int check

[Ian Romanick]

On 01/09/2013 11:02 AM, Eric Anholt wrote:
> Jordan Justen <jordan.l.justen at intel.com> writes:
>
>> In ES or GL+GL_ARB_ES2_compatibility, the usage of
>> format = IMPLEMENTATION_COLOR_READ_FORMAT +
>> type = IMPLEMENTATION_COLOR_READ_TYPE
>> can function, even if the src/dst int vs. non-int types
>> differ.
>
> This seems bogus -- why should you get to read to formats that ought to
> be invalid?  I bet what we're missing is an implementation of this bit
> of spec: "The implementation-chosen format may vary depending on the
> format of the selected read buffer of the currently bound read
> framebuffer." (section 4.3 of the gles3 spec) which lets us actually
> specify a format that makes sense for an int framebuffer.

I think you're right.  This is also why tests that try to 
glReadPixels(GL_RED) from a GL_RED FBO work on other implementations but 
generate an error on ours.  I think we should have the 
IMPLEMENTATION_COLOR_READ_* match the format / type of the FBO itself.