Bug 6098

Summary:	Wrong normals with GL_AUTO_NORMAL
Product:	Mesa	Reporter:	Thomas Zimmermann <tzimmermann>
Component:	Mesa core	Assignee:	mesa-dev
Status:	RESOLVED MOVED	QA Contact:
Severity:	normal
Priority:	high	CC:	idr
Version:	6.4
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	Testcase

Description Thomas Zimmermann 2006-03-03 00:30:08 UTC

Hi,

i use 2d evaluators to draw a grid. The grid points are arranged, so that the
parameter u walks along +x and v walks along -z. Calling glEvalMesh() renders a
grid with front faces pointing upwards. (I tested this by explicitly culling
back faces.)
The grid patches normals where generated with GL_AUTO_NORMAL. I guess normals
should also point upwards, but the lighting in the scene behaves, as if normals
where pointing downwards.
Calling glFrontFace(GL_CW) reverses normals as expected, but they still point
into the wrong direction.

The system is Linux 2.6.13, Mesa 6.4.2 SW-Renderer on Xorg 6.7

Regards,

Thomas Zimmermann
tdz@users.sourceforge.net

Comment 1 Ian Romanick 2009-11-09 18:28:02 UTC

Are you still able to reproduce this bug?  Do you have a small test case?

Comment 2 Thomas Zimmermann 2009-11-10 07:55:13 UTC

Created attachment 31092 [details]
Testcase

The attached file contains a testcase for this bug. Instructions are included in the source file.

I reported this ages ago, so I'm not sure whether the testcase actually shows the same bug. Maybe I just misunderstood the behavior of the evaluator functions. However, the lighting in the testcase program still looks strange to me, so I guess the bug is still there.

Regards, Thomas

Comment 3 Thomas Zimmermann 2009-11-10 07:57:04 UTC

BTW, I'm on a Fedora 11 system with an Intel 945 graphics card.

Comment 4 GitLab Migration User 2019-09-18 20:21:43 UTC

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