Hi all, Defining a coordinate system for OSG is a good idea. Though to me the most important aspect of reader and writers, is that this expression must be true:
read( write( A ) ) = A Rizzen Sukender wrote: > Hi Ulrich, Paul, and all, > > I agree we should unify the coordinate system during loading AND writing. > Here are my suggestions : > - Have plugins do NO rotation by default (reading and writing) when the > format doesn't have coordinate system information (that is to say all but FBX > and maybe FLT). > - Have plugins read and apply coordinate system information if available by > default when reading. > - Have optionnal READING options: > - readXup, readYup, readZup to suppose model is X, Y or Z-up (overrides > format's coordinate system information) > - readLeftHanded, readRightHanded (similar setting) > - When in conflict (two options defined), use the latest one > - Have optionnal WRITING options: > - writeXup, writeYup, writeZup, writeLeftHanded, writeRightHanded (which > should almost never be supported, in my opinion) > - Let plugings optionnally support these options prefixed with their name and > "_". For instance "3ds_readYup" would assume ONLY ".3ds" files are Y-up. > These would take precedence over the general settings. > - Also support "pluginName_read/writeAutoUp" and > "pluginName_read/writeAutoHanded", which would specifically deactivate a > global setting for a given plugin. For instance, "fbx_readAutoUp" would let > the plugin decide the up vector (here using coordinate system information in > the .fbx). "3ds_readAutoUp" would mean "no rotation" for .3ds. > - Write a portion of code somewhere in osgDB to parse all these options and > store it in a nice structure (to avoid each plugin duplicating code). To be > called with something like "myStructure = > osgDB::readStandardCoordinateSystemOptions(PLUGIN_NAME)". > - As OpenGL doesn't have a "etched in stone" orientation standard, use the > osgGA as an "internal" standard (that is to say +Z up, right handed) when a > change is needed. > > 1. Please raise your hand if you agree, and tell about changes you'd like to > introduce in this summary. > 2a. Please mention all plugins you know which break these rules. > 2b. Please tell if you agree modifying those plugins. > > When all is ok, I'll code it. > > Cheers, > > Sukender > PVLE - Lightweight cross-platform game engine - http://pvle.sourceforge.net/ > > ----- "Ulrich Hertlein" <[email protected]> a écrit : > > >> On 29/12/09 6:52 PM, Paul Martz wrote: >> >>> Paul Martz wrote: >>> >>>> I've noticed the same thing with OBJ. >>>> >>> A little digging reveals that the OBJ plugin has a "noRotation" >>> >> Option >> >>> that disables the x axis rotation. The rotation is only done on >>> >> file >> >>> load, not on file write. >>> >>> Rotation about x is on by default. I'd suggest a change to off by >>> default, and the Option changed to "doRotation" to enable it. >>> >> The .x plugin has 'leftHanded' and 'rightHanded'. Maybe we could >> establish a common >> option for this type of functionality (one that does 'convert to >> right-handed, Z-axis up'). >> >> There already are options with (apparently) related functionality >> (courtesy of 'osgconv >> --formats'): >> >> Coordinate system: >> obj:noRotation >> x:leftHanded >> x:rightHanded >> >> Optimization: >> obj:generateFacetNormals >> obj:noTriStripPolygons >> stl:generateNormals >> stl:smooth >> stl:tristrip >> >> Image orientation >> hdr:NO_YFLIP >> hdr:YFLIP >> x:flipTexture >> >> Cheers, >> /ulrich >> _______________________________________________ >> osg-users mailing list >> [email protected] >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
