On Tuesday 07 September 2004 19:10, Andy Ross wrote: > Lee Elliott wrote: > > In a/c that have one or more VC views there's a visible 'jitter' > > when looking at parts of the a/c, most notably in my experience, > > with the windshield/canopy frames. > > This is a bug, not an intentional feature. :) > > It's a precision problem with the view code. The current architecture > puts the coordinate origin at the current tile origin, which is > sometimes ~1000m from the viewpoint. > > So the OpenGL matrix stack has to do something like > > + move the origin from the viewpoint (where it starts, by definition) > to the tile centroid > + draw scenery, objects... > + move the origin back to the aircraft origin > + draw the aircraft, cockpit ... > > These two matrix multiplications result in floating point values that > are "off" by a few parts in 2^23 (basically one part ), due simply to > roundoff error in the single precision operations. Doing the math, > that comes out to an error of about 1mm. In small cockpits (the A-4 > shows this effect really well), that can be several pixels worth of > screen. > > I looked at fixing it about a year or so ago, but got confused and > distracted by other things. The best solution would be to "recreate" > the cockpit modelview matrix from scratch, using double-precision math > for the offsets, instead of deriving it from the tile centroid with > OpenGL matrix calls. > > Andy >
& Erik Oops :) LeeE _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
