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+--- Thread: graphical artifacts (/showthread.php?tid=1334)
graphical artifacts - alex25 - 08-11-2010
there seems to be some kind of shadow following the car around but only if the shaders are turned on (this is on linux with an nvidia card). i am attaching a series of pictures illustrating the problem:
![[Image: shadow1.jpg]](http://caliban.lbl.gov/vdrift/shadow1.jpg)
![[Image: shadow2.jpg]](http://caliban.lbl.gov/vdrift/shadow2.jpg)
![[Image: shadow3.jpg]](http://caliban.lbl.gov/vdrift/shadow3.jpg)
![[Image: shadow4.jpg]](http://caliban.lbl.gov/vdrift/shadow4.jpg)
the shadow seems to exist only on vertical surfaces and it moves with the camera. if the shaders are off everything looks like on the brighter side of the wall.
--alex--
- portets - 08-11-2010
also linux with nvidia. i cannot reproduce though.. hmm....
tried with 256.44 and 195.36.24 drivers, gf 9600m gs, ubuntu 10.04 64-bit, rv2847, data rv671
- alex25 - 08-11-2010
portets Wrote:also linux with nvidia. i cannot reproduce though.. hmm....
did you try it on hungaroring at the same places? i also see this right away at interlagos. this with the shaders on shadows, bloom, normal maps, motion blur off. ambient occlusion is off, reflection quality low
- portets - 08-11-2010
strange, i don't know how i didn't see it before. i can actually reproduce it with any combination of settings with shaders on. even with shadows off.
- joevenzon - 08-12-2010
Good catch.
I looked at this in some detail and I'm pretty sure it's occurring because those pieces of geometry have weird normals. The abrupt transition of shading is occurring because that's where the normal is actually pointing backward away from the camera, so the shader is flipping it to point back at the camera.
In data R672 I changed the way I correct backward-pointing normals so that it reflects the normal back at the camera instead of flipping it. It's less correct for double sided surfaces, but it prevents the abrupt shading change for cases like this.
- alex25 - 08-12-2010
no joy. now it's even worse:
![[Image: latest.jpg]](http://caliban.lbl.gov/vdrift/latest.jpg)
--alex--
- joevenzon - 08-13-2010
:oops:
That's a debug visualization I was using. I forgot to re-enable the normal shader path. Fixed in 673.
:oops:
- alex25 - 08-13-2010
the shadows artifacts seem to be gone. thanks.
--alex--
- portets - 08-13-2010
joevenzon Wrote:That's a debug visualization I was using
do normal maps work in this mode? it might help me make them, if so.
- joevenzon - 08-14-2010
Yes. All I had done there was commented out parts of the shader so that the only thing showing was the ambient light, and ignored diffuse textures (as if they were white).