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Guest cbuchner1

Hooking as an alternative to the tileproxy.sys driver

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Development progress is kind of slow right now on Tileproxy. I do not have a lot of spare time for TP right now.Let me just quickly state that earlier this month I've been experimenting with "hooking" techniques as a potential alternative to the filesystem filter driver. Hooking means patching entry points to the Win32 API for a specific application (FSX.exe) with the intention to intercept these calls.This provides the capability to more directly feed the texture data into the sim (less overhead...). I have already had some success with this, but sometimes the CPU's Data Execution Prevention (DEP) prevents me from hooking all of the CreateFile/ReadFile API calls. There was a lot of trial and error to get this running and it's still a bit of a hit and miss.An interesting aspect of this hooking technique is that I get access to the stack frame of the sim. What does that mean? It allows me to perform some observation of the variables on the stack and with some smart patching it might be possible to make FSX load more tiles at once... and load them faster. There is clearly some potential to influence the behavior (algorithm) of FSX regarding the tile loading.But so far I haven't done any analysis of the stack yet and it would be somewhat risky to mess with the internal variables of FSX. This is also extremely version dependent (RTM and SP1 would have different stack frame layout because the terrain+texture loading code is much different). But this has some potential and should be investigated further, time permitting...

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Ok most of what you said went straight over my head but it sounds like your going in the right direction. So what has been the reception if any from the folks at ACES? Do you think they like what your doing or don't like it? I'm guessing payware creators of scenery don't like it.Regardless don't give up!! Please!! This has made the sim extreemly enjoyable to me again.Marc

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Cool stuff.Keep it going Christian.We are all looking forward to your next developement.RegardsRichard

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Hi Christian,If you don't mind me saying...I think that hooking into the internals of FSX will be a never ending chasing the tail game when MS comes out with SP2 or DX10 mods or something else. IMHO I think that the next step would be to convert the FS9 BMPs to BGLs as MatthewS is attempting to do. Your 'proof of concept' has been amply demonstrated with Beta5. We already know that MS left a few hiccups in FSX like the 'late loading of mipmaps' etc which adds to the blurry woes experienced by Tileproxy disciples. Your proxy service adds a bit more code, a few more cycles, into the delicate balance of FSX routines that slows down lower spec machines (ie less than 2 cores!) from getting fast enough access to those beautiful photoscenery files.Some users have asked if there is a way to convert an area to photoscenery and the solution IMHO is to marry Tileproxy with FSX KML and FSX Photoscene.My 2c.

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> IMHO I think that the next step would be to convert the FS9 BMPs to BGLs as MatthewS is attempting to do. I don't think that I'll be the one providing such a conversion tool. In fact I'll be going exactly in the opposite direction and limit the amount of data that is going to be stored in your RAM, cache and world folders. So the data can continually refresh itself (allowing for example for updates on the map servers to make their way to your hard drive).

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I think my program will remain a niche product and can't ever reach the quality of payware addons that focus on limited regions.I believe Aces won't like it too much because it means that more people will be asking them to keep and maintain the inefficient "FS9 code path" for quite a while to come. The more demand there is for a backwards compatibility feature, the less likely it is that it can be dropped in the next release. And maintaining backwards compatibility is always a pain ;)

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I disagree Chris, its the best addon i had for years, and hopefully more years to come, even when i have to pay for it. Keep up the good work.Gr.

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You are far over my head too Christian but just know that you have made a bunch of us happy with TP.

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>Some users have asked if there is a way to convert an area to>photoscenery and the solution IMHO is to marry Tileproxy with>FSX KML and FSX Photoscene.I do agree - both approaches combined would be the best solution: Download your favorite places once to create a permanent photoscenery that can be kept forever (that's where Photoscene is apparently going), cache other areas temporarily while you fly there and free them after some time of not accessing their files or when a size limit is reached (that's where Tileproxy seems to be going).So I thank both authors for working on their individual goals and am looking forward to the final products which will improve VFR flying in FSX by an amazing amount! THANK YOU SO MUCH! Keep up the great work!When I tried TileProxy for the first time, I was thrilled. For the first time I could really fly a circuit as in real life over my home airport (of which no "normal" scenery exists) - I didn't have such fun with any flight simulator ever before! Being German, I'm using TileProxy together with German Landmarks X and Simviation's excellent freeware mesh of Germany, so it's as real as it gets... :)

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