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bugfix: Don't normalize zero-length normals 

git-svn-id: http://svn.clifford.at/openscad/trunk@545 b57f626f-c46c-0410-a088-ec61d464b74c
stl_dim
kintel 2010-05-10 18:14:12 +00:00
parent 135b51b8c0
commit 8a592d34e7
1 changed files with 5 additions and 2 deletions
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7
src/export.cc
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@ -120,9 +120,12 @@ void export_stl(CGAL_Nef_polyhedron *root_N, QString filename, QProgressDialog *
double nx = (y1-y2)*(z1-z3) - (z1-z2)*(y1-y3);
double ny = (z1-z2)*(x1-x3) - (x1-x2)*(z1-z3);
double nz = (x1-x2)*(y1-y3) - (y1-y2)*(x1-x3);
double n_scale = 1 / sqrt(nx*nx + ny*ny + nz*nz);
double nlength = sqrt(nx*nx + ny*ny + nz*nz);
// Avoid generating normals for polygons with zero area
double eps = 0.000001;
if (nlength < eps) nlength = 1.0;
fprintf(f, " facet normal %f %f %f\n",
nx * n_scale, ny * n_scale, nz * n_scale);
nx / nlength, ny / nlength, nz / nlength);
fprintf(f, " outer loop\n");
fprintf(f, " vertex %s\n", vs1.toAscii().data());
fprintf(f, " vertex %s\n", vs2.toAscii().data());