Hi, I have a question.
I have a 3d model of an aircraft that I want to rotate in roll, pitch, and yaw just like any other aircraft. I also have "stream lines" from a CFD program that I would like to display at the same time over the top of the model. (Hi Matthias) :-) My aircraft is a "skydiver" and the way the 3d model and FDM are setup, it basically falls straight nose down (pitch -90) so that alpha is close to zero. (The 3d model is adjusted so that it is in the correct pose when falling. When pitch and roll are zero it is standing straight up and down ... so nose over to a -90 degree pitch angle and he is falling face down like he should be.) The streamlines basically need to stay vertical no matter what the orientation the 3d model is at since we are always falling pretty much straight down or close enough. I had been copying off some of our "fake shadow" hacks to rotate the streamline model in -roll and -pitch to keep it aligned straight up and down. That almost works -- except most of the time we are flying very near a pitch angle of -90. This puts us at a euler angle singularity. What happens is that the streamlines stay properly positioned straight up and down as I intend, but as we get closer and closer to that magic pitch angle of exactly straight down, the heading angle starts to blow up. The result is that the streamline heading orientation doesn't track the model orientation correctly and the errors get worse and worse the closer we are to a pitch angle of -90. Is there any other way to attach a sub model to the aircraft model, but control the submodel orientation in NED space rather than having to hack a transform opposite of the model roll/pitch angles? Thanks, Curt. -- Curtis Olson: http://www.atiak.com - http://aem.umn.edu/~uav/ http://www.flightgear.org - http://gallinazo.flightgear.org
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