vec4 worldSpaceCameraPosition = osg_ViewMatrixInverse * vec4(0,0,0,1);//you can use just translation column(or row?) of matrix instead vec4 worldSpaceVertexPosition = osg_ViewMatrixInverse * gl_ModelViewMatrix * gl_Vertex; vec4 worldSpaceVectorFromCameraToVertex = osg_ViewMatrixInverse * vec4((gl_ModelViewMatrix * gl_Vertex).xyz, 0.0);
Cheers 13.09.2011, 20:30, "Conan Doyle" <[email protected]>: > How would I calculate the actual world positions, not distances, of the > camera and the vertices? > > CD > > hybr wrote: > >> Hi, Conan >> >> gl_ModelViewMatrix * gl_Vertex is position of vertex in camera space >> If your view matrix dont have scale component, you dont need anything else >> to calculate distance (by distance i mean vector length) >> In general case you can use: >> osg_ViewMatrixInverse * gl_ModelViewMatrix * gl_Vertex <- this is world >> space vector from camera to vertex >> >> Cheers, >> Sergey. >> >> 13.09.2011, 18:19, "Conan Doyle" <>: >>> 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 >>> >>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> _______________________________________________ >> osg-users mailing list >> >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> >> ------------------ >> Post generated by Mail2Forum > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=42716#42716 > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
