I have observed and found a problem with the software renderer.
The problem happens only when we use float valued 32 bit osmesa contexts.
When we have float valued render buffers the convert_color_type function in s_span.c is not called and the
is not set to the place in the span that would be otherwise set by the convert_color_type function.
The attached patch sets the rgba pointer to the value that matches the semantics of the convert_color_type function but the unneeded conversion is omitted.
The test case is in this case very deep in an application that does shader programs with OSMesa. I was not able to construct a simple testcase that illustrates the problem.
The patch is originally against Mesa 7.7, but still applies against todays git.
Please apply or fix appropriately
Created attachment 37771 [details] [review]
Patch to the software renderer
Sorry, I am pretty sure that I had filled that already in the initial new bug page. To be honest, I fail to get the initial patch often. But I do not know what I miss in the initial bug page so that the initial submission gets sent without patch.
Thanks. Patch applied as commit c8e714df013cdf360602f9cc96d26cb732b19a32 (with minor changes).