OSG: Calculate the world transformation matrix, normal vector, and vertex coordinates of a node in nodevisitor.

Class mynodevisitor: Public OSG: nodevisitor

{

Pulic:

Mynodevisitor (): OSG: nodevisitor (OSG: nodevisitor: traverse_all_children)

{}

Void apply (OSG: geode & geode)

{

// Calculate the world transformation matrix corresponding to the current geode node, used to calculate the world coordinates corresponding to the vertex in geode

OSG: matrix geodematrix = OSG: computelocaltoworld (getnodepath ());

Unsigned int COUNT = geode. getnumdrawables ();

For (unsigned int geomidx = 0; geomidx <count; geomidx ++)

{

OSG: geometery * geometry = geode. getdrawable (geomidx)-> asgeometry ();

If (! Geometry) continue;

// Vertex data

OSG: vec3array * vertices = dynamic_cast <OSG: vec3array *> (geometry-> getvertexarray ());

// Normal Vector

OSG: vec3array * normals = dynamic_cast <OSG: vec3array *> (geometry-> getnormalarray ());

// Index the Array

For (unsigned int primitiveidx = 0; primitiveidx <geometry-> getnumprimitivesets (); ++ primitiveidx)

{

OSG: primitiveset * PS = geometry-> getprimitiveset (primitiveidx );

If (! PS) continue;

Switch (PS-> GetType ())

{

Case OSG: primitiveset: drawelementsushortprimitivetype:

{

OSG: drawelementsushort * Deus = dynamic_cast <OSG: drawelementsushort *> (PS );

Const unsigned int indexnum = Deus-> getnumindices ();

Switch (Deus-> getmode)

{

Case OSG: primitiveset: triangles:

// Suppose geometry-> getnormalbinding () = OSG: geometry: bind_per_vertex)

// Each vertex corresponds to a normal vector.

 

For (unsigned int I = 0; I <indexnum; I ++)

{

// Vertex Index

Unsigned int idx = Deus-> at (I );

// Normal vector. To convert it to world coordinates, multiply it by the inverse matrix transpose of geodematrix. For details, refer to the article on calculation of normal vectors.

Vec3 normalworld = Normals-> at (idx) * (transpose the inverse matrix of geodematrix );

// Vertex coordinates

Vec3 vertexworld = vertices-> at (idx) * geodematrix;

}

Break;

}

}

}

}

}

}

}

OSG: Calculate the world transformation matrix, normal vector, and vertex coordinates of a node in nodevisitor.