It looks like Peter's function assumes a parallel projection where the camera is facing -z. I wonder what would be useful in a 3 dimensional space. I can imagine the following scenarios with mapping mouse coordinates:<br>
<ul><li>Intersection of the ray of that pixel's position/direction in 3D coordinates with the XY, YZ, or XZ planes depending on the camera position and type (parallel or perspective).</li><li>Intersection of the ray of that pixel's position/direction and an object that it touches. If it doesn't intersect an object it could either return a point at infinity or an intersection with a plane.</li>
</ul>Implementation would probably involve inspection of the z buffer at that pixel along with Peter's reverse projection. What would a nice interface look like?<br><br>David<br><br><br>2008/11/29 Peter Verswyvelen <<a href="mailto:bugfact@gmail.com">bugfact@gmail.com</a>>:<br>
> The windowPoint function in Reactive/GLUT/SimpleGL.hs has the following<br>> comment:<br>> -- | Convert a window position to a logical X,Y. Logical zero is at the<br>> -- origin, and [size??].<br>> -- <br>
> -- TODO: this def is completely broken. What do I even want? Probably to<br>> -- go backward through the viewing transform to the XY plane.<br>> The function I made in the past for doing this is:<br>><br>> windowPoint :: GL.Position -> IO (Double,Double)<br>
> windowPoint pos@(GL.Position x y) = <br>> do<br>> viewport@(_,GL.Size _ height) <- get GL.viewport<br>> modelviewMatrix <- getMatrix $ GL.Modelview 0<br>> projectionMatrix <- getMatrix $ GL.Projection<br>
> let pos3 = GL.Vertex3 (fromIntegral x) (fromIntegral (height-y)) 0<br>> GL.Vertex3 vx vy _ <- GLU.unProject pos3 modelviewMatrix<br>> projectionMatrix viewport<br>> return (vx,vy)<br>> where<br>
> getMatrix :: GL.MatrixMode -> IO(GL.GLmatrix Scalar)<br>> getMatrix mode = get $ GL.matrix $ Just mode<br>><br>><br>> _______________________________________________<br>> Reactive mailing list<br>
> <a href="mailto:Reactive@haskell.org">Reactive@haskell.org</a><br>> <a href="http://www.haskell.org/mailman/listinfo/reactive">http://www.haskell.org/mailman/listinfo/reactive</a><br>><br>><br><br><br><br>-- <br>
David Sankel<br>