double
areaPolygon3D( const SoMFVec3f& point, const SoMFInt32& indices, const SbVec3f& normal )
{
int numIndices = indices.getNum();
if( numIndices < 3 )
return 0;
double area = 0;
SoMFVec3f tmpPoint;
const int* iPtr = indices.getValues(0);
for( int i = 0; i < numIndices; ++ i, ++ iPtr )
{
if( *iPtr == -1 )
{
area += areaPolygon3D( tmpPoint, normal );
tmpPoint.setNum(0);
}
else
{
tmpPoint.set1Value( tmpPoint.getNum(), point[*iPtr] );
}
}
return area;
}
void doClipping(SbVec3f trans, SbRotation rot)
{
SbMatrix mat;
SbVec3f normal;
mat.setTransform(trans, rot, SbVec3f(1,1,1));
mat.multDirMatrix(SbVec3f(0, -1, 0), normal);
SbPlane plane(normal, trans);
const float coords[][3] = {
{-5,-5,-5},
{5,-5,-5},
{5,5,-5},
{-5,5,-5},
{-5,-5,5},
{5,-5,5},
{5,5,5},
{-5,5,5}
};
const int indices[] = {
0,3,2,1,-1,
0,1,5,4,-1,
2,6,5,1,-1,
3,7,6,2,-1,
3,0,4,7,-1,
7,4,5,6,-1
};
// Clip box against plane
SbClip clip;
SoMFVec3f * globalVerts =
(SoMFVec3f *)SoDB::getGlobalField(SbName("globalVerts"));
SoMFVec3f * globalTVerts =
(SoMFVec3f *)SoDB::getGlobalField(SbName("globalTVerts"));
SoMFInt32 * globalnv =
(SoMFInt32 *)SoDB::getGlobalField(SbName("globalnv"));
globalVerts->startEditing();
globalVerts->setNum(0);
globalTVerts->startEditing();
globalTVerts->setNum(0);
globalnv->startEditing();
globalnv->setNum(0);
int i;
for (i = 0;i<6*5;i++) {
if (indices[i] == -1) {
clip.clip(plane);
int numVerts = clip.getNumVertices();
if (numVerts > 0) {
for (int j = 0;j<numVerts;j++) {
SbVec3f v;
clip.getVertex(j, v);
globalVerts->set1Value(globalVerts->getNum(), v);
v += SbVec3f(5, 5, 5);
v /= 10.0;
globalTVerts->set1Value(globalTVerts->getNum(), v);
}
globalnv->set1Value(globalnv->getNum(), numVerts);
}
clip.reset();
}
else clip.addVertex(coords[indices[i]]);
}
globalVerts->finishEditing();
globalTVerts->finishEditing();
globalnv->finishEditing();
// Close hole in clipped box by clipping against all 6 planes
const SbVec3f planecoords[] = {
SbVec3f(-10,0,-10),
SbVec3f(10,0,-10),
SbVec3f(10,0,10),
SbVec3f(-10,0,10)
};
clip.reset();
for (i = 0;i<4;i++) {
SbVec3f v;
mat.multVecMatrix(planecoords[i], v);
clip.addVertex(v);
}
for (i = 0;i<6*5;i+=5) {
SbPlane p(coords[indices[i+2]],
coords[indices[i+1]],
coords[indices[i]]);
clip.clip(p);
}
int numVerts = clip.getNumVertices();
SoMFVec3f * planeVerts =
(SoMFVec3f *)SoDB::getGlobalField(SbName("planeVerts"));
SoMFVec3f * planeTVerts =
(SoMFVec3f *)SoDB::getGlobalField(SbName("planeTVerts"));
planeVerts->startEditing();
planeVerts->setNum(0);
planeTVerts->startEditing();
planeTVerts->setNum(0);
for (i = 0;i<numVerts;i++) {
SbVec3f v;
clip.getVertex(i, v);
planeVerts->set1Value(planeVerts->getNum(), v);
v += SbVec3f(5, 5, 5);
v /= 10.0;
planeTVerts->set1Value(planeTVerts->getNum(), v);
}
planeVerts->finishEditing();
planeTVerts->finishEditing();
}