I have a 3D point (Point1) and I have a 2D screen coodinate.
I want to take the current camera view angle as a plane normal and “push” the plane back along that normal until it touches Point1. I then want to project a line from my 2D coordinates along that normal until it intersects the plane. The resulting 3D coodinate of that last intersection is what I need.
I really thought I could gluProject Point1 to get the screen Z. Then pluUnProject my 2D coordinates using that Z and find what I needed. I haven’t had much luck getting anything useful from UnProject though.
A short version of what my code kinda looks like:
gl:matrixMode(?GL_PROJECTION), gl:loadIdentity(), glu [img]http://www.opengl.org/discussion_boards/ubb/tongue.gif[/img]erspective(45.0, W/H, 0.25, 1000.0), gl:matrixMode(?GL_MODELVIEW), gl:loadIdentity(), gl:translatef(0.0, 0.0, -Dist), gl:rotatef(Elevation, 1.0, 0.0, 0.0), gl:rotatef(Azimuth, 0.0, -1.0, 0.0), ModelMatrix = gl:getDoublev(?GL_MODELVIEW_MATRIX), ProjMatrix = gl:getDoublev(?GL_PROJECTION_MATRIX),
I can post more, but I’m wondering if there is something wrong with the way I’m rotating/translating, causing the weird values I get back from UnProject.
Thanks for any info!