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From Gordon Tomlinson, fixes to BoundingSphere::expandBy(BoundingSphere&)

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Robert Osfield 2007-01-25 10:02:20 +00:00
parent 577313ae7d
commit 13dd5acb63
1 changed files with 42 additions and 23 deletions
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57
src/osg/BoundingSphere.cpp
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@ -54,31 +54,50 @@ void BoundingSphere::expandRadiusBy(const Vec3& v)
void BoundingSphere::expandBy(const BoundingSphere& sh)
{
if (sh.valid())
{
if (valid())
{
Vec3 dv = sh._center-_center;
float dv_len = dv.length();
if(dv_len == 0 && sh._radius>_radius) {
_radius = sh._radius;
}
else if (dv_len+sh._radius>_radius)
{
Vec3 e1 = _center-(dv*(_radius/dv_len));
Vec3 e2 = sh._center+(dv*(sh._radius/dv_len));
_center = (e1+e2)*0.5f;
_radius = (e2-_center).length();
} // else do nothing as vertex is within sphere.
}
else
// This sphere is not set so use the inbound sphere
if (!valid())
{
_center = sh._center;
_radius = sh._radius;
return;
}
// Calculate d == The distance between the sphere centers
double d = ( _center - sh.center() ).length();
// New sphere is already inside this one
if ( d + sh.radius() <= _radius )
{
return;
}
// New sphere completely contains this one
if ( d + _radius <= sh.radius() )
{
_center = sh._center;
_radius = sh._radius;
return;
}
// Build a new sphere that completely contains the other two:
//
// The center point lies halfway along the line between the furthest
// points on the edges of the two spheres.
//
// Computing those two points is ugly - so we'll use similar triangles
double new_radius = (_radius + d + sh.radius() ) * 0.5;
double ratio = ( new_radius - _radius ) / d ;
_center[0] += ( sh.center()[0] - _center[0] ) * ratio;
_center[1] += ( sh.center()[1] - _center[1] ) * ratio;
_center[2] += ( sh.center()[2] - _center[2] ) * ratio;
_radius = new_radius;
}