Hello Daniel,
On 07/13/2012 05:23 AM, Daniel Weber wrote:
i've observed problems with the automatic computation of normals when reading
triangular meshes from .off files. The direction of the normals is simply
wrong. I know that there has already been a discussion on this mailing list,
suggesting to simply flip the normals after the node has been generated.
But when I use other file formats the normals are computed correctly. I
therefore used Meshlab (and Blender) to generate a simple sphere and saved it
in different file formats: .wrl. obj. and .off. (I've attached the files). In
the attached example, the lighting looks wrong for the .off, whereas .obj and
.wrl.are rendered correctly. I assume, that it is a bug in the .off file reader
that accidentally flips indices of the triangles. If I load different file
formats, I always need to check the file ending for flipping the normals
afterwards or not. For me it would help a lot, if this distinction was not
necessary. Can anybody point me to the routines for loading the .off files and
(automatically) computing the normals? Maybe, i can send a patch then.
it appears the .off file reader reverses the order of vertices in a
face. The file format descriptions I could find with a quick search
don't mention if the faces are given in CCW or CW order. Given the
problem you are running into it seems to me the loader should better
preserve the orientation from the file, the attached patch should do that.
Could you give it a try please?
Cheers,
Carsten
diff --git a/Source/System/FileIO/OFF/OSGOFFSceneFileType.cpp b/Source/System/FileIO/OFF/OSGOFFSceneFileType.cpp
index e78238e..5ed9e99 100644
--- a/Source/System/FileIO/OFF/OSGOFFSceneFileType.cpp
+++ b/Source/System/FileIO/OFF/OSGOFFSceneFileType.cpp
@@ -338,8 +338,10 @@ NodeTransitPtr OFFSceneFileType::read( std::istream &is,
if(fN == i)
{
- n += vN = UInt32(faceVec[j].size());
- for(k = vN - 1; k >= 0; k--)
+ vN = UInt32(faceVec[j].size());
+ n += vN;
+
+ for(k = 0; k < vN; ++k)
{
index->editFieldPtr()->push_back(faceVec[j][k]);
}
@@ -366,7 +368,7 @@ NodeTransitPtr OFFSceneFileType::read( std::istream &is,
pType = 0;
break;
}
-
+
if(pType)
{
lens->push_back(n);
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