Hi, I want to calculate the distance between my final render cameras position and the vertices of each object rendered. I want to pass the world position of the camera into a shader and then use gl_Vertex position to perform the calculation. In search the OSG website, the net and this forum (as I understand a good OSG newbie should) I found the following
http://www.openscenegraph.org/projects/osg/wiki/Support/Tutorials/CameraControlFindingWorldCoordinates > "Where in the world am I? > To compute where a particular node is the scene graph is, in world > coordinates, you need to acquire the accumulated 4x4 matrix from the root of > the scene graph down to your node. osg::Node contains a convenience method, > Node::getWorldMatrices(..), that walks the parental chain from your node to > the root(s) of your scene graph, returning a list of matrices. A list of > matrices is returned rather than a single matrix as the OpenSceneGraph > supports sharing of nodes, so they may have multiple parents, and if the > parent chain has separate transforms in them the different paths will result > in different matrices - in this case you node is effectively in more than one > place at once! Multiple parents would be typical in cases such as a wheel > subgraph that is reused four times on a car, each with a transform above it > to place it in the appropriate place. > To use this feature use code such as: > > osg::MatrixList worldMatrices = myNode->getWorldMatrices(); > > for(osg::MatrixList::iterator itr = worldMatrices.begin(); > itr != worldMatrices.end(); > ++itr) > { > osg::Matrix& matrix = *itr; > osg::Vec3 center = myNode->getBound().center() * matrix; > std::cout<<"Node "<<myNode->getName()<<" center = "<<center<<" > worldMatrix = "<<matrix<<std::end; > } > " > I am wondering if this is what I need to do... with myNode being my viewer camera node, and then getting the worldMatrix for it.... If so, how do I get the position from the worldMatrix? Conan Thank you! Cheers, Conan ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=42702#42702 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
