Daniel Borchart writes:
>
> Hi,
>
> I'm trying to implement a bump mapping shader. That works well for a simple
shape like that plane, where I
> define the tangent attribute manually:
>
> Code:
> Geometry* plane = new Geometry();
>Vec3Array* vertices = new Vec3Array();
> Vec3Array* normals = new Vec3Array();
> DrawElementsUInt* faces = new DrawElementsUInt
(PrimitiveSet::TRIANGLES, 0);
> Vec3Array* texcoords = new Vec3Array();
> Vec3Array* tangents = new Vec3Array();
>
> vertices->push_back(Vec3f(1.0f, 0.0f, 1.0f));
> vertices->push_back(Vec3f(-1.0f, 0.0f, 1.0f));
> vertices->push_back(Vec3f(1.0f, 0.0f, -1.0f));
> vertices->push_back(Vec3f(-1.0f, 0.0f, -1.0f));
>
> normals->push_back(Vec3f(0.0f, -1.0f, 0.0f));
>
> texcoords->push_back(Vec3f(1.0f, 1.0f, 1.0f));
> texcoords->push_back(Vec3f(0.0f, 1.0f, 1.0f));
> texcoords->push_back(Vec3f(1.0f, 0.0f, 1.0f));
> texcoords->push_back(Vec3f(0.0f, 0.0f, 1.0f));
>
> faces->push_back(0);
> faces->push_back(1);
> faces->push_back(3);
> faces->push_back(3);
> faces->push_back(2);
> faces->push_back(0);
>
> tangents->push_back(Vec3(-1,0,0));
>
> plane->setVertexArray(vertices);
> plane->setNormalArray(normals);
> plane->setTexCoordArray(0, texcoords);
> plane->addPrimitiveSet(faces);
> plane->setNormalBinding(Geometry::BIND_OVERALL);
>
> plane->setVertexAttribData(6, Geometry::ArrayData(tangents,
Geometry::BIND_OVERALL));
>
> But for more complex shapes I have to use the TangentGenerator. When I try
to run this:
>
> Code:
> ref_ptr tsg = new
osgUtil::TangentSpaceGenerator();
> tsg->generate(plane, 0);
>
> I get an "Debug Assertion Failed" with "Expression: vector subscript out of
range" in generate().
>
> Did I forget something? I cannot see the fault.
>
> Daniel
>
> --
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=35575#35575
>
>
Hi Daniel,
I come up against the same problem of utilizing osgUtil::TangentSpaceGenerator
in the same way. I trace into TangentGenerator.cpp then I find that on line
223 the subscript of normal array(nx) is out of range when there is only one
normal in it. TangentSpaceGenerator is assumed to work for normal binding of
BIND_PER_VERTEX instead of BIND_OVERALL. So you have to set normal for EVERY
vertex. If I miss something, please let me know.
Guo
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