hi guys, i hope you can help me with my current problem. what i'm trying to achieve is picking an object from a render to texture scene. The current structure of my scenegraph is containing: - a main camera - a RenderToTextre-camera - a plane (rendered by the mainCam), which gets it's texture from the RTT-camera - a sub-scene (bunch of spheres) rendered by the RTT-camera.
So as the user clicks onto the plane, a corresponding ray should be sent into the subscene and tested for collisions. Both cameras are perspective ones. My current approach can be described as following: - use the mouse-coordinates of the viewer to send a first ray into the main scene. - check if the ray hits the plane - if so, get the uv-coordinates of the plane at the ray-hitpoint - as the hit uv-coordinate corresponds to a pixel of the the RTT-camera's viewport, use this position as the origin of a second ray sent into the sub-scene.. The actual problem i encounter is how to calculate the direction of the second ray? (although i know what to do in theory) Unproject the 2D-coordinate of the viewport-point to a line in 3D-space. Therefore i have to calculate 2 positions of the line, one on the nearplane and another on the farplane. But how do i achieve this?? First i normalize the recieved uv-coords (x/y) to ranges between -1 and 1. Then i create two Vec3 of it, one with z=0 (nearplane) one with z=1 (farplane) and multiply both with the inverse viewProjectionMatrix of the RTT-camera, so i get two world-coordinates. Subtracting near - far, i should get a vector which gives me the direction of the ray. But it seems i'm missing something, somewhere. Could one of you guys give me a hint what i'm missing?! Or point me to some code-snippets where this is done? Regards, Manuel -- GMX DSL Doppel-Flat ab 19,99 €/mtl.! Jetzt auch mit gratis Notebook-Flat! http://portal.gmx.net/de/go/dsl _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
