Hi Vivian, 2013/5/7 Vivian Meazza <[email protected]>: > Thanks, interesting. As a non-Blender user (it makes my brain hurt) the > references are a bit obscure.
If you get used to Blender its a really powerful tool (I have problems if trying to work with other modelling programs :P) and with using the right scripts it gets a very neat tool for creating models for FlightGear. For example for a gear scissor just add an armature with two bones, add an IK constraint to the second bone and attach an element of the scissor to each bone, and you are done. You can watch the animation in Blender and using an exporter script now it is possible to watch exactly the same animation inside FlightGear. You don't need to guess any coordinates/axes/etc. and if you modify and object you just have to export it again, without manually modifying the animation xml. > Are the various axes always orthogonal? There are (currently) only two axes required. The lock-axis and the track-axis. They should be orthogonal, as the rotation is only possible round the lock-axis. Internally the track-axis is always orthonormalized to the lock-axis, as calculations always are performed in the plane normal to the lock-axis. > Can they also be specified in the alternate form: > > <axis> > <x1-m>5.1821</x1-m> > <y1-m>0.221496</y1-m> > <z1-m>0.794147</z1-m> > <x2-m>4.99208</x2-m> > <y2-m>0.114133</y2-m> > <z2-m>0.842884</z2-m> > </axis> Currently the alternate form is not possible. The problem is that we have two axes crossing at the same center, so which of the axes should specify the center? Also the center/axis form clearly states where the center is located, which is not the case with the alternate form (the center is located halfway between the two given points). For the rotate animation the exact location of the center along the axis is not relevant, but for the tracking animation it is. Also as one would probably not create the xml by hand, using multiple notations would not gain us anything. > If non-orthogonal axes are allowed they are difficult in the > <center>/<axis> form in the example in the wiki. > > Perhaps, when you have time, the information could be consolidated in > > http://wiki.flightgear.org/Howto:Animate_models and > fgdata/Docs/model-howto.html I will do if timer permits :) Yesterday I have added some images. I don't know if you have already seen them. > Looks like valuable work to me: gear scissor links were very difficult with > the existing animations. That was the initial reason for creating it. But now it is also useful for creating complex kinematic systems as can be found for landing gears and their doors. Tom ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. This 200-page book is written by three acclaimed leaders in the field. The early access version is available now. Download your free book today! http://p.sf.net/sfu/neotech_d2d_may _______________________________________________ Flightgear-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/flightgear-devel
