Quoting Roberto Inzerillo: > I wonder how do textures impact on fps against simply colored 3d objects. > > I have a bunch of raw 3d objects to put into a scenery, they look very rough > because of lack of details. Fps performance is very good. Well, I could make > them look much nicer by applying textures to them. This will eat graphic > card's memory of course, but I really don't know if that will impact on > graphic performance as well. Will I get a drop down performance just by > applying textures? Or the only effect will consist in eating up all the AGP > card memory?
Graphic cards are optimized to texture objects. The greatest penalty is when you do state changes. A state is all attributes that affect the rendering of a primitive ( point, line or triangle ). A color change is heavy as well as a texture change. The new Paris Scenery can display lots of identical building just because they use the same texture. That way, you can draw hundreds of building with a single state change. If these buildings where designed using 2 textures, there will be 2 state changes for each building, so hundreds of state changes, and that wouldn't be playable. Texture size has a litle impact on filtering time and a huge one when card memory is completely filled. In that situation, swapping begins and very low fps are encountered. > There's another question. I am used to creating high detailed objects for low > distance view and a second low detailed copy for high distance view. That > speeds up the simulator when the object is distant but ... does FGFS unload > the unused high detailed 3d object (and its texture file) from the graphic > cards memory? The complete model stay in memory, as well as textures. There is a gain because less primitives and less state changes are processed by the GPU. LOD has also an effect on the visual because displaying sub pixel features usually creates flickers. Using Shared models helps saving memory. That way, only one model is loaded, and it is displayed multiple times. With static objects, every instance is loaded in memory, with duplicates on geometry and textures. Changing OBJECT_STATIC to OBJECT_SHARED helped having a decent fps over Paris, as well as reducing texture size to avoid GPU memory saturation. -Fred -- Frédéric Bouvier http://frfoto.free.fr Photo gallery - album photo http://www.fotolia.fr/p/2278 Other photo gallery http://fgsd.sourceforge.net/ FlightGear Scenery Designer _______________________________________________ Flightgear-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/flightgear-devel
