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Guest GerrishGray

Textures vs. Frame Rates - a few questions.

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Hi All- In designing the structures for my airport, I would like to make them as frame rate friendly as possible. 1.If you had two walls both the same size; the first is a single large rectangle with ten windows drawn on it; the second wall is the same size but made up of ten individal rectangles with a window drawn on them. Which wall is more frame rate friendly? 2. Is a simple rectangular building,with textures only on the outside of the walls, more frame rate friendly than the same building with textures on the outside and the inside of the walls?[i'm thinking of a hanger with the doors open so you can see the inside]. 3. When moving past a building,are the frame rates a factor of what the computer is seeing in the field of view[the building]or are the objects behind the building, that are out of sight[trees, other buildings,etc.] being considered by the computer as well? Thanks for your time. Ken

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1. I'm not exactly sure what you mean here - are you making the second wall by using ten polygons? If so, then the first wall should provide better perforemance.2. Yes. If you have to draw the inside walls, then you are creating more work for the sim. On all my buildings, I search for polygons that will never be visible and delete them.3. Both. Any object within the field of view (or maybe radius?) need to be loaded into memory. On top of this, any object actually visible needs to be drawn on the screen. I "think" the way it works is that complicated objects created with many polygons create a load on the CPU when they are loaded into memory. On top of this, when the object is actualyl visible, your graphics card needs to laod the textures into its memory, and then draw the object on the screen, which creates a load on the graphics card.It's good to see people still thinking about effeciency. :) There are other ways to improve framerates, such as using LOD models, and limiting the distance at which objects can be seen. Also, using library objects (not sure what you are using to model) is very helpful, especially on those objects which you want to place several times.- Martin

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Hi KenTo expand on Martin's reply, here are some suggested rules for frame-rate-friendly buildings/airports1. Use as few different texture sheets as possible. Loading a texture takes a good deal of time.2. Use the DXT1 format for your textures and do not include an alpha channel unless you need transparency. If you need partial 'hazed' transparency use DXT3 (but don't use this format otherwise because it has some problems!), or consider using an untextured material - see 6.3. Use as few polygons/rectangles in your design as possible. If your particular modelling tool offers it, consider using LOD models (i.e. simpler versions when viewing from a distance, more complex versions only when close up).4. If your modelling tool allows it, limit the maximum visibility range of your buildings and other objects - the smaller the object the shorter the maximum visibility range should be. Only the largest objects need to be visible for more than a few kilometers, and the smallest might be culled at just a few hundred meters. Trial and error when testing your scenery will give you a good idea.5. Do not draw 'hidden' surfaces such as internal walls etc UNLESS they are actually going to be seen (e.g. the inside of a hangar that aircraft are going to park in, or a simple representation of the inside of a control tower that is going to be seen through its windows). Note that FS determines for itself which of the EXTERNAL surfaces of an object are presently visible, depending on the relative position of the viewpoint - you don't normally have to worry about this.These first five rules are the most important, especially 1-3. The remaining five factors are also significant: 6. Consider using simple 'materials' without textures for certain surfaces (e.g. semi-transparent glass, plain metal, etc) and also for the more distant models when using LOD.7. Don't waste time and frame rates modelling small details that nobody will really see, unless perhaps you are using LOD models so that they will not affect frame rates except when close to the building. Detail is often best dealt with by a 'photographic' texture that shows the fine detail but is applied to a simple (e.g. rectangular) building. Remember that this is a FLIGHT simulator, NOT an architectural modelling system!8. Use up-to-date modelling tools. Only gMax, NovaSim (NOT Nova) and FSDS2 (NOT version 1) use up-to-date frame rate friendly techniques for compiling your model to a BGL.9. Library objects are quicker if you repeat the same model more than once in the same scene. Microsoft actually use library objects for everything these days, but this doesn't have much affect on frame rates for one-off models.10. If you are modelling for FS2004 exclusively, use the FS2004 version of gMax, converting the models to library objects via MakeMDL and BGLComp. Other tools will appear in due course, but until they do this is the best choice and possibly the only one that will produce scenery that will be forwards-compatible with future versions of FS. However, FS2004 is very 'forgiving' and DOES support models made with all the older techniques and tools (even really old tools such as VOD, EOD, FSDS1, Nova etc). For the moment, NovaSim is worth considering because it is simpler to use than gMax, produces very frame rate friendly models, and has some interesting facilities not available in the other tools, whilst FSDS2 has the advantage of offering LOD modelling - although its real strength is aircraft modelling more than scenery objectsTo answer your question about buildings behind the aircraft, they still consume some resources, as Martin explained, but not as much as when they are in view. FS automatically avoids wasting time on actually trying to draw these buildings, although they are still held in memory and their visibility has to be checked for every frame: a built-in visibility detection mechanism culls the drawing of objects that are not in the field of view. With pre-FS2004/gMax modelling tools we had some control over this with a parameter known to scenery designers as the "V2 radius", but this is not required with the latest gMax/FS2004 technique. Apart from this V2 factor, you should NOT waste time trying to control 'behind the aircraft' culling with your own visibility checks because FS does it better and quicker and adding your own checks is just a waste of time.Hope this helps a bitGerrish

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Hi Gerrish,This is just to welcome you back to the forum! :-)Regards, Luis

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Hi LuisSorry I have been absent of late. Like Mark Twain, rumours of my demise are somewhat exaggerated, but I have been terribly busy with other business and have been unable to devote much time to simming of late.I wish I had time to contribute to progress on those 'other tools' I mentioned earlier, because we do now know how to create FS2004-style BGL's without being forced into the gMax - MakeMDL route. It just needs someone to complete the job and although I have plans in that direction I don't have the time ... In the meantime, Arno does at least have some tools for tweaking gMax models.Kind RegardsGerrish

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