Please do not reply to this email: if you want to comment on the bug, go to
the URL shown below and enter yourcomments there.
https://bugs.freedesktop.org/show_bug.cgi?id=4992
Summary: glClear vs rendering with 16 bits per channel
Product: Mesa
Version: CVS
Platform: PC
OS/Version: Windows 2000
Status: NEW
Severity: minor
Priority: P4
Component: Mesa core
AssignedTo: [email protected]
ReportedBy: [EMAIL PROTECTED]
When comparing the pixel colours from glClear and normal rendering it was found
that the same colour differed by one pixel value. This was found to be caused
by glClear (in s_buffers.c, function clear_rgba_buffer) using the macro
FLOAT_TO_USHORT which truncates while the normal rendering pipeline (in
t_vertex_generic.c) uses the macro UNCLAMPED_FLOAT_TO_USHORT which rounds. So
for a pixel value expected to be 2.52 the glClear calculated 2 and the
rendering pipeline calculated 3.
This was resolved simply resolved by substituting the latted macro in the
glClear case. Therefore the lines 135 to 138 were changed to
UNCLAMPED_FLOAT_TO_USHORT(clear16[0], ctx->Color.ClearColor[0]);
UNCLAMPED_FLOAT_TO_USHORT(clear16[1], ctx->Color.ClearColor[1]);
UNCLAMPED_FLOAT_TO_USHORT(clear16[2], ctx->Color.ClearColor[2]);
UNCLAMPED_FLOAT_TO_USHORT(clear16[3], ctx->Color.ClearColor[3]);
This resolved the problem for this specific instance.
--
Configure bugmail: https://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.
-------------------------------------------------------
SF.Net email is sponsored by:
Tame your development challenges with Apache's Geronimo App Server. Download
it for free - -and be entered to win a 42" plasma tv or your very own
Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php
_______________________________________________
Mesa3d-dev mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
