Bug 11050 - Y coordinate should be round down when draw points
Summary: Y coordinate should be round down when draw points
Alias: None
Product: Mesa
Classification: Unclassified
Component: Mesa core (show other bugs)
Version: git
Hardware: Other Linux (All)
: medium minor
Assignee: mesa-dev
QA Contact:
Depends on:
Reported: 2007-05-23 20:01 UTC by WuNian
Modified: 2009-08-24 12:26 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:


Description WuNian 2007-05-23 20:01:36 UTC
When draw a point with call:
       glVertex2f(x, y);

The point location will depend on x,y coord, the current implementation is:
x=1.4, y=1.4, point will be drawn at (1,1);
x=1.9, y=1.4, point will be drawn at (1,1);
x=1.4, y=1.9, point will be drawn at (1,2);

Y coord is round to the nearest integer, X is round down to the nearest integer.
The X,Y coord should be tread equally and Y should be round down instead of round.
Comment 1 Brian Paul 2007-05-24 08:23:04 UTC
This might be within spec.  Appendix H of the OpenGL programming guide (OpenGL correctness tips) explains that a 0.375 translation factor should be used when you're trying to hit specific window coords.  You might want to look into that.

Comment 2 Michael Fu 2008-01-03 23:04:25 UTC
update status.
Comment 3 WuNian 2008-01-08 15:59:59 UTC
I do not think this bug is result from 0.375 translation factor. But now when assign point's location at (x=1.4, y=1.9), point will be drawn at (1,1), so this bug has gone.
Comment 4 Adam Jackson 2009-08-24 12:26:57 UTC
Mass version move, cvs -> git

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