Vivian Meazza wrote: >Roberto > > > >>Sent: 04 November 2007 09:55 >> >>Hi, >> I've been modeling for fgfs a few objects around the world. >>I'm used to >>output everything as .AC files since it looks to me it's the >>most used >>format in FGFS but that has a few limitations that I'd like >>not having. >> >>The one I'm concerned now is the "crease angle" limitation. >>AC3D makes me set a crease angle for an entire object and >>does not let >>me choose to set different crease angles to each surface >>inside the same >>object. >> This does not make sense. A crease angle is used to compute the normals at the *shared* vertices of an object. It's because the normal is shared amoung adjacent faces that the object appears smooth (the normal vectors of the faces sharing this vertex is averaged). Setting random normals for adjacent faces will not make it appear smooth, this is called flat shading.
>>... >> >> > >You are quite right AC3D has crease angle set on a per-object basis, and >AFAIK, there is no way round this. I have not found it a limitation - it is >a transition value between crease and smooth. Like you, if there isn't a >convenient value I break the object. There's no penalty for that - numbers >of objects and groups have no performance penalty. > >Vivian > > > Models are usually split because of the animations of parts, or because there is several textures used (or because it's easier for the modeler). But having lots of objects with different 'attributs/animations' has some serious impact on performance. The performance of a modern 3D card is inversely proportional to the number of opengl calls (objects in our case), the number of poly has no impact. Note that some object loader can 'optimize' some objects (with identical attributes) and merge them at load time. So like you said, in a favorable case we don't care about the number of objects ;) HJ. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
