Re: [osg-users] picking and custom active area
Hi Stefan,
stefan nortd schrieb:
So I found some code for intersecting a line with a plane.
What I am missing is how do I translate the mouse pointer
coordinates into a line expressed in local coordinates?
Here the intersection code if anybody is interested:
There's a class called osg::Plane which you can use to do some
plane-ray-intersections:
double dist = _dragPlane.distance(mouseloc);
double numerator = -dist;
double denominator = _dragPlane.getNormal() * normalizedMouseRay;
if (0.0 == denominator) { // is on Plane
return true;
}
else
{
pointOnDragPlane = mouseloc + (normalizedMouseRay *
numerator/denominator);
}
the plane, mouseloc and normalizedMouseRay are in local coordinates.
To convert the mouseloc into local coordinates you'll have to
backproject the coordinates.
I do this via:
// get the coords in screen-space:
float tx = cefix::MouseLocationProvider::instance()-getNativeX();
float ty = cefix::MouseLocationProvider::instance()-getNativeY();
osg::Vec3 mouseloc = osg::Vec3(tx, ty, 0) * _invMatrix;
osg::Vec3 normalizedMouseRay = (osg::Vec3(tx, ty, 1) * _invMatrix) -
mouseloc;
The last question which remains: where comes _invMatrix from:
I get the nodepath of the picked object (it's basically a list of
transforms which affects this specific node) and compute a
localToWorld-matrix. I need the current cam to get view + projection matrix.
osg::Matrix MVPW = osg::computeLocalToWorld(nodepath) *
cam-getViewMatrix() * cam-getProjectionMatrix();
// include the viewport:
if (cam-getViewport())
MVPW.postMult(cam-getViewport()-computeWindowMatrix());
_inverseMat.invert(MVPW);
This code is basically the same as in osg, where picking is done.
cheers,
Stephan
___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] picking and custom active area
Thanks Stephan, you answer was very helpful. After some headbanging I have it
working seemingly flawless. Here is the code for reference:
Code:
osg::Vec3d rayIntersectWithXYPlane(float x, float y, osg::Node* widget) {
// flip mouse y axis
y = ofGetHeight() - y; //important
osg::Vec3d isect = osg::Vec3d(0,0,0);
// compute model to window transform
// Model*View*Projection*WindowMatrix
osg::Matrixd matrix;
matrix.postMult(widget-getWorldMatrices()[0]);
matrix.postMult(camera-getViewMatrix());
matrix.postMult(camera-getProjectionMatrix());
matrix.postMult(camera-getViewport()-computeWindowMatrix());
osg::Matrixd inverse;
inverse.invert(matrix);
// Transform ray from window to model coordinates
osg::Vec3d startRay = osg::Vec3d(x,y,0) * inverse;
osg::Vec3d endRay = osg::Vec3d(x,y,1) * inverse;
// Intersect ray with XY-plane
// (0,0,1,0) is plane in hess normal form
getPlaneLineIntersection(osg::Vec4d(0,0,1,0), startRay, endRay, isect);
return isect;
}
bool getPlaneLineIntersection(const osg::Vec4d plane,
const osg::Vec3d lineStart, const osg::Vec3d
lineEnd,
osg::Vec3d isect)
{
// intersects an infinite line with an infinite plane
// in hesse normal form Ax + By + Cz + D = 0
// A,B,C is the normal vector of the plane, D the distance to the origin
const double deltaX = lineEnd.x() - lineStart.x();
const double deltaY = lineEnd.y() - lineStart.y();
const double deltaZ = lineEnd.z() - lineStart.z();
const double denominator = (plane[0]*deltaX + plane[1]*deltaY +
plane[2]*deltaZ);
if (! denominator) return false;
const double C = (plane[0]*lineStart.x() + plane[1]*lineStart.y() +
plane[2]*lineStart.z() + plane[3]) / denominator;
isect.x() = lineStart.x() - deltaX * C;
isect.y() = lineStart.y() - deltaY * C;
isect.z() = lineStart.z() - deltaZ * C;
return true;
}
Instead of osg::computeLocalToWorld(...) I use getWorldMatrices(...) which I
believe does pretty much the same. I also use this
getPlaneLineIntersection(...) for doing the actual intersection.
I have one more quick question. What is generally meant in osg with world
coordinates? For example in computeLocalToWorldMatrix(). Is it simply the
coordinates in the parent or all the way up to the root node? I would assume
it's all the way up to the root but I read some code that makes me think
otherwise.
Thanks again,
/stefanix
--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=13960#13960
___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] picking and custom active area
So far so good. The culling works as expected. I can now define a custom active invisible area and the picking works with it. Unfortunately it did not quite tackle my problem with dragging. The question have now: How do I manually intersect a ray with the x/y-plane of geode? The problem I have is that when I drag an object, the mouse pointer (in my case it is actually one of multiple touches) momentarily leaves it within one frame and the move handler that adjusts the new location is never called. My first approach was to increase the active area so that this does not happen but this leads to all kinds of problems and is not fully robust, conceptually speaking. Instead I would like to do the following: Objects get clicked on, I do normal picking. On mouse drag and up I do manual ray intersection with the entire x/y plane of the object that got the mouse down previously. This way the object never miss out on the drag/up. So how do I manually intersect a ray with the x/y-plane of geode? /stefanix -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=13953#13953 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] picking and custom active area
So I found some code for intersecting a line with a plane.
What I am missing is how do I translate the mouse pointer
coordinates into a line expressed in local coordinates?
Here the intersection code if anybody is interested:
Code:
bool getPlaneLineIntersection(const osg::Vec4d plane,
const osg::Vec3d lineStart, const
osg::Vec3d lineEnd,
osg::Vec3d isect)
{
// intersects an infinite line with an infinite plane
// in hesse normal form Ax + By + Cz + D = 0
// A,B,C is the normal vector of the plane, D the distance to the
origin
const double deltaX = lineEnd.x() - lineStart.x();
const double deltaY = lineEnd.y() - lineStart.y();
const double deltaZ = lineEnd.z() - lineStart.z();
const double denominator = (plane[0]*deltaX + plane[1]*deltaY +
plane[2]*deltaZ);
if (! denominator) return false;
const double C = (plane[0]*lineStart.x() + plane[1]*lineStart.y() +
plane[2]*lineStart.z() + plane[3]) / denominator;
isect.x() = lineStart.x() - deltaX * C;
isect.y() = lineStart.y() - deltaY * C;
isect.z() = lineStart.z() - deltaZ * C;
return true;
}
--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=13954#13954
___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] picking and custom active area
I think I just found some code that would do what I want. Let me know if there
is a better way of doing this both in regard of the custom active area and the
drag issue.
So I found this in osgManipulator but I belive I could use this code
independantly of it. The idea is to add a cull callback that does nothing and
returns true.
Code:
class ForceCullCallback : public osg::Drawable::CullCallback
{
public:
virtual bool cull(osg::NodeVisitor*, osg::Drawable*, osg::State*) const
{
return true;
}
};
void osgManipulator::setDrawableToAlwaysCull(osg::Drawable drawable)
{
ForceCullCallback* cullCB = new ForceCullCallback;
drawable.setCullCallback (cullCB);
}
--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=13917#13917
___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] picking and custom active area
Hi Stefan, So I found this in osgManipulator but I belive I could use this code independantly of it. Yes, definitely. This will work even outside osgManipulator (I was going to reply pointing you to this very code, glad you found it by yourself) The reason why this works is that the drawable on which this callback is attached will always be culled and so never be displayed (the return true does that) but it will still be traversed during intersection tests and so you'll be able to pick it. Hope this helps, J-S -- __ Jean-Sebastien Guayjean-sebastien.g...@cm-labs.com http://www.cm-labs.com/ http://whitestar02.webhop.org/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
