material problem issue

Discussions about LuxRender's materials, and how to make the most of them.

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Re: material problem issue

Postby patro » Mon Sep 13, 2010 8:26 am

I'm trying and trying... and finally to me it seams to be more a camera related problem.

for example I had try at time only with cameras created from a front, back, left, right view. by rotating the camera from the original position... back faces are showed as black.

now I try to create a camera in a perspective view... not related to any of the above listed views..... well this camera can be rotated freely and no black faces are to see. also log don't report any normals related errors :o
but objs can't still rotated freely in any view from original creation position! if you rotate it... some faces are still rendered black!
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Re: material problem issue

Postby jeanphi » Mon Sep 13, 2010 10:08 am

Hi,

Could you create a very simple scene (like a single triangle but with shading normals), export it once without rotation and once with rotation and compare geometry files? I guess the normals are either not properly rotated during export or rotated twice or something like that.

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Re: material problem issue

Postby patro » Mon Sep 13, 2010 10:15 am

jeanphi wrote:Hi,

Could you create a very simple scene (like a single triangle but with shading normals), export it once without rotation and once with rotation and compare geometry files? I guess the normals are either not properly rotated during export or rotated twice or something like that.

Jeanphi

Yes I will do it later and post. ... sorry for my question, what do you mean for triangle? a planar surface with 3 vertex or a solid with 4?

btw, please give a look to this image:
download/file.php?id=10179&mode=view
you can notice that the chamferbox show a black contour silhouette.. the normals are exported flipped. the chamferbox isn't rotated.
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Re: material problem issue

Postby jeanphi » Mon Sep 13, 2010 10:35 am

patro wrote:Yes I will do it later and post. ... sorry for my question, what do you mean for triangle? a planar surface with 3 vertex or a solid with 4?

A single triangle should do.

patro wrote:btw, please give a look to this image:
download/file.php?id=10179&mode=view
you can notice that the chamferbox show a black contour silhouette.. the normals are exported flipped. the chamferbox isn't rotated.

It might be that the box is smoothed and that the normal on the far edge is pointing away from the camera. If so regarding the shading normal the camera might be below the surface.

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Re: material problem issue

Postby patro » Mon Sep 13, 2010 10:46 am

hi Jeanphi,
front view
download/file.php?id=10178&mode=view
back view
download/file.php?id=10179&t=1
you will notice that are always the far from camera the edges of the chamferboxes that have some black faces.

no smooth is applied to the chamferbox, the fillet have 10 segments

triangle test front
1luxout.png

triangle test front rotated
3luxout.png
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Re: material problem issue

Postby jeanphi » Mon Sep 13, 2010 10:58 am

Hi,

I'd like to see the luxrender scene files with the geometry data.

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Re: material problem issue

Postby patro » Mon Sep 13, 2010 11:04 am

sorry...
triangle test front.lxs
(1.57 KiB) Downloaded 25 times

triangle test front rotated.lxs
(1.88 KiB) Downloaded 20 times

jeanphi wrote:It might be that the box is smoothed and that the normal on the far edge is pointing away from the camera. If so regarding the shading normal the camera might be below the surface.
Jeanphi

I give a look to the geometry... and yes there is a basic smooth applied... but it's not an additional modifier...
anyway I try a test by disabling the smooth.... but the result is the same... black faces.
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Re: material problem issue

Postby hedphelym » Mon Sep 13, 2010 2:33 pm

very strange problem.
I'll keep an eye out on this thread, and implement any changes needed to make this work correctly in luxmax.

Currently I have no solution or ideas as to what it can be.
thanks to both of you for trying to find the solution.
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Re: material problem issue

Postby patro » Mon Sep 13, 2010 2:39 pm

hedphelym wrote:very strange problem.
I'll keep an eye out on this thread, and implement any changes needed to make this work correctly in luxmax.

Currently I have no solution or ideas as to what it can be.
thanks to both of you for trying to find the solution.


if you want I can share my max scene and you can check it, and also try to export and render on your system!
and see what happen!
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Re: material problem issue

Postby hedphelym » Mon Sep 13, 2010 2:55 pm

yes please share them.
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