"I've made a few changes to osgUtil::PolytopeIntersector so that it
actually uses double precision floating point numbers everywhere (as
long as OSG_USE_FLOAT_PLANE is not defined).
I needed double precision intersections in a project I am working on.
These changes fixed the problems I was having -- this is all testing I
have done.
Notice that I have changed
osgUtil::PolytopeIntersector::Intersection's members to use doubles
(osg::Vec3d, instead of osg::Vec3). I could have added #ifdef's there
too, but I think it is better to not change the types of stuff in the
public interface depending on some preprocessor definition.
The modified files are attached. A diff also follows, for those who like it."
With the following changes from Robert Osfield:
"I've just reviewed your changes and have just tweaked them a little to
streamline them. What I have done in the PolytopeIntersector header
is add:
typedef osg::Plane::Vec3_type Vec3_type;
And then use this typedef in the definition of the vertices rather
then Vec3d as you did. Next changes were to PolytopeInteresector.cpp
where to the PolytopeIntersectorUtils defintions of the Vec3_type, and
value_type which now simply read:
typedef osg::Plane::Vec3_type Vec3_type;
typedef Vec3_type::value_type value_type;
This way I was able to complete avoid any if def's and have essential
the same implementation as you achieved. Changes now checked into
svn/trunk."
CID 11827: Uninitialized scalar field (UNINIT_CTOR)
Non-static class member _plane_mask is not initialized in this constructor nor in any functions that it calls.
enhanced version of PolytopeIntersector.
New features of PolytopeIntersector :
* Dimension mask: The user may specify the dimensions of the
primitives to be tested. Checking polytope-triangle and
polytope-quad intersections is rather slow so this can
be turned off.
* Reference plane: The resulting intersections are sorted
by the distance to this plane.
New memebers of PolytopeIntersector::Intersection :
* distance: Distance of localIntersectionPoint to the reference plane
* maxDistance: Maximum distance of all intersectionPoints to the
reference plane.
* intersectionPoints: The points intersecting the planes of the polytope
or points completely inside the polytope.
* localIntersectionPoint: arithmetic mean of all intersection points
* primitiveIndex: Index of the primitive that intersected
I added some more output to the example osgkeyboardmouse."
"Since we desperately needed a means for picking Lines
and Points I implemented (hopefully!) proper geometrical tests
for the PolytopeIntersector.
First of all I implemented a new "GenericPrimiteFunctor"
which is basically an extended copy TriangleFunctor which also
handles Points, Lines and Quads through suitable overloads of
operator(). I would have liked to call it "PrimitiveFunctor"
but that name was already used...
I used a template method to remove redundancy in the
drawElements method overloads. If you know of platforms where
this will not work I can change it to the style used
in TriangleFunctor.
In PolytopeIntersector.cpp I implemented a
"PolytopePrimitiveIntersector" which provides the needed
overloads for Points, Lines, Triangles and Quads to
the GenericPrimitiveFunctor. This is then used in the
intersect method of PolytopeIntersector.
Implementation summary:
- Points: Check distance to all planes
- Lines: Check distance of both ends against each plane.
If both are outside -> line is out
If both are in -> continue checking
One is in, one is out -> compute intersection point (candidate)
Then check all candidates against all other polytope
planes. The remaining candidates are the proper
intersection points of the line with the polytope.
- Triangles: Perform Line-Checks for all edges of the
triangle as above. If there is an proper intersection
-> done.
In the case where there are more than 2 polytope
plane to check against we have to check for the case
where the triangle encloses the polytope.
In that case the intersection lines of the polytope
planes are computed and checked against the triangle.
- Quads: handled as two triangles.
This is implementation is certainly not the fastest.
There are certainly ways and strategies to improve it.
I also enabled the code for PolytopeIntersector
in osgkeyboardmouse and added keybindings to
switch the type of intersector ('p') and the picking
coordinate system ('c') on the fly. Since the
PolytopeIntersector does not have a canonical
ordering for its intersections (as opposed to
the LineSegementIntersector) I chaged the
implementation to toggle all hit geometries.
I tested the functionality with osgkeyboardmouse
and several models and it seems to work for
polygonal models. Special nodes such as billboards
do not work.
The next thing on my todo-list is to implement
a an improved Intersection-Structure for the
PolytopeIntersector. We need to know
which primitives where hit (and where).
"
