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Improved accuracy of spheresegment to mesh intersections uses mathematical

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models of surface geometry.
This commit is contained in:
Robert Osfield
2005-09-16 14:52:56 +00:00
parent a154348d9a
commit 68d22f8de7
1 changed files with 95 additions and 6 deletions
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101
src/osgSim/SphereSegment.cpp
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@@ -1676,6 +1676,23 @@ struct TriangleIntersectOperator
}
};
bool computeQuadraticSolution(double a, double b, double c, double& s1, double& s2)
{
// avoid division by zero.
if (a==0.0) return false;
double inside_sqrt = b*b - 4.0*a*c;
// avoid sqrt of negative number
if (inside_sqrt<0.0) return false;
double rhs = sqrt(inside_sqrt);
s1 = (-b + rhs)/(2.0*a);
s2 = (-b - rhs)/(2.0*a);
return true;
}
struct AzimIntersector
{
AzimIntersector(TriangleIntersectOperator& tif, double azim):
@@ -1721,9 +1738,21 @@ struct AzimIntersector
}
else
{
edge->_intersectionType = TriangleIntersectOperator::Edge::MID_POINT;
double r = (_azim-azim1)/(azim2-azim1);
double dx = v2.x()-v1.x();
double dy = v2.y()-v1.y();
double t = tan(_azim);
double div = dx - t*dy;
if (div==0.0)
{
edge->_intersectionType = TriangleIntersectOperator::Edge::NO_INTERSECTION;
return false;
}
double r = (t*v1.y()-v1.x()) / div;
double one_minus_r = 1.0f-r;
edge->_intersectionType = TriangleIntersectOperator::Edge::MID_POINT;
edge->_intersectionVertex = v1*one_minus_r + v2*r;
}
@@ -1776,9 +1805,40 @@ struct ElevationIntersector
}
else
{
edge->_intersectionType = TriangleIntersectOperator::Edge::MID_POINT;
double r = (_elev-elev1)/(elev2-elev1);
double dx = v2.x()-v1.x();
double dy = v2.y()-v1.y();
double dz = v2.z()-v1.z();
double t = tan(_elev);
double tt = t*t;
double a = dz*dz-tt*(dx*dx + dy*dy);
double b = 2.0*(v1.z()*dz - tt*(v1.x()*dx + v1.y()*dy));
double c = v1.z()*v1.z() - tt*(v1.x()*v1.x() + v1.y()*v1.y());
double s1, s2;
if (!computeQuadraticSolution(a,b,c,s1,s2))
{
edge->_intersectionType = TriangleIntersectOperator::Edge::NO_INTERSECTION;
return false;
}
double r = 0.0;
if (s1>=0.0 && s1<=1.0)
{
r = s1;
}
else if (s2>=0.0 && s2<=1.0)
{
r = s2;
}
else
{
osg::notify(osg::NOTICE)<<"neither segment intersects s1="<<s1<<" s2="<<s2<<std::endl;
edge->_intersectionType = TriangleIntersectOperator::Edge::NO_INTERSECTION;
return false;
}
double one_minus_r = 1.0-r;
edge->_intersectionType = TriangleIntersectOperator::Edge::MID_POINT;
edge->_intersectionVertex = v1*one_minus_r + v2*r;
}
@@ -1825,9 +1885,38 @@ struct RadiusIntersector
}
else
{
edge->_intersectionType = TriangleIntersectOperator::Edge::MID_POINT;
double r = (_tif._radius-radius1)/(radius2-radius1);
double dx = v2.x()-v1.x();
double dy = v2.y()-v1.y();
double dz = v2.z()-v1.z();
double a = dx*dx + dy*dy + dz*dz;
double b = 2.0*(v1.x()*dx + v1.y()*dy + v1.z()*dz);
double c = v1.x()*v1.x() + v1.y()*v1.y() + v1.z()*v1.z() - _tif._radius*_tif._radius;
double s1, s2;
if (!computeQuadraticSolution(a,b,c,s1,s2))
{
edge->_intersectionType = TriangleIntersectOperator::Edge::NO_INTERSECTION;
return false;
}
double r = 0.0;
if (s1>=0.0 && s1<=1.0)
{
r = s1;
}
else if (s2>=0.0 && s2<=1.0)
{
r = s2;
}
else
{
osg::notify(osg::NOTICE)<<"neither segment intersects s1="<<s1<<" s2="<<s2<<std::endl;
edge->_intersectionType = TriangleIntersectOperator::Edge::NO_INTERSECTION;
return false;
}
double one_minus_r = 1.0-r;
edge->_intersectionType = TriangleIntersectOperator::Edge::MID_POINT;
edge->_intersectionVertex = v1*one_minus_r + v2*r;
}