I would like to point the attention of people who can commit on flightgear and simgear to two merge requests put in by Vivian recently:
https://www.gitorious.org/fg/simgear/merge_requests/26 https://www.gitorious.org/fg/flightgear/merge_requests/1564 This contains functionality which is relevant for Advanced Weather, and it would be very good to have this in before feature freeze. The context is as follows: When I restructured the Advanced Weather code to remove stutter, I (knowingly) introduced a bug by removing the Nasal-generated motion of 2d Cirrus clouds and rain layers. The need to move 2d clouds around was a large chunk of what caused uneven framerate, and I eliminated the Nasal code for movement since the benefits in terms of smooth framerate outweigh the potential problem. That problem is that 3d clouds are done by a different rendering technique than the 2d Cirrus cloud models or the rain layers. All 3d clouds move with the wind, and if we have no way of moving 2d clouds and rain layers, they'd stay behind. For instance, in a storm, you'd see the cloud front approaching but the rain front would simply be left behind disconnected from clouds. Similarly, I sometimes do ridge-riding with a glider where the winds are quite strong but I stay basically in the same location. In this case, you see the weather drifting over you and new tiles are essentially generated because the tile coordinate reference moves, not because the aircraft position moves. If Cirrus clouds would not move, they'd all pile up in the same location in the sky as new tiles are generated, creating very ugly artefacts. In many situations though you wouldn't see the lack of movement of some objects (i.e. if winds are weak or if no 2d Cirrus or rain layers are in the scene), so the bug is not immediately crippling. The curse of weather modelling is - once you move anything with the wind, you have to move everything or you create artefacts. As I've learned, it's much easier never to move anything around, and from an airliner, you never even see the difference. But it wouldn't do to drift with an airship through static clouds... The patches are an attempt to provide a hard-coded (and garbage-collector-save) means to move a limited number of Cirrus clouds and Rain layers. I have a matching bugfix ready for Advanced Weather and I have tested the patches and the bugfix for the last few days, so far I have not observed any problem which I could relate to the patches. I would therefore ask that the patches are committed to have a 2.8 without the unmoving rain bug. Best, * Thorsten ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
