[Flightgear-devel] Plea for help: geometry/trigonometry problem
I'm fixing the magnetic compass instrument to make its behaviour more realistic. I'm starting with the northernly turning error, and found a useful site that actually gives an equation: http://williams.best.vwh.net/compass/node4.html Here's the equation (radians for all angles): Hc: indicated compass heading Hm: actual magnetic heading phi: bank angle (right positive; the original web page uses theta) mu: magnetic dip angle (down positive) Hc = atan2(sin(Hm)cos(phi) - tan(mu)sin(phi), cos(Hm)) The result is very realistic as far as bank/turning errors go, much better than anything I've seen in a desktop sim. I've checked in the changes so that others can take a look. The problem is that this equation assumes that pitch (theta) is 0. Now, I need to adapt this equation to incorporate theta as well, so that the compass will show an error when the nose is pitched up or down relative to the earth's surface. I imagine that the problem is fairly obvious to people with a basic knowledge of geometry and trig, but unfortunately, I am not one of those people. I would be very grateful for someone could reply with an adaption of the above equation integrating theta. Thanks, and all the best, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
David Megginson wrote: I'm fixing the magnetic compass instrument to make its behaviour more realistic. Oh, my god, no more nice flight sim The trouble already began with the Beaver startup procedure ;-)) I imagine that the problem is fairly obvious to people with a basic knowledge of geometry and trig, but unfortunately, I am not one of those people. I would be very grateful for someone could reply with an adaption of the above equation integrating theta. Explaining in pictures is easier than dealing with single-line- equations :-) We'll see, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 15:36:33 + (UTC), Martin Spott [EMAIL PROTECTED] wrote: Explaining in pictures is easier than dealing with single-line- equations :-) We'll see, Multiple, sequential equations are welcome as well. Anything, really ... Thanks, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
David Megginson wrote: On Wed, 3 Nov 2004 15:36:33 + (UTC), Martin Spott [EMAIL PROTECTED] wrote: Explaining in pictures is easier than dealing with single-line- equations :-) We'll see, Multiple, sequential equations are welcome as well. Anything, really ... Could you go into detail about what kind of compass/error we're talking ? Is it a conventional whiskey compass, so I assume no gyro driven instrument ? I mean how is it modelled or what is the cause ? That way it might be easier to come up with a formula/solution... My first VERY simple *guess* would be that it might be because of an imbalance in inertia of a compasses moving parts as soon as the pitch changes accordingly. --- Boris ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 03 Nov 2004 17:25:16 +0100 Boris Koenig [EMAIL PROTECTED] wrote: David Megginson wrote: On Wed, 3 Nov 2004 15:36:33 + (UTC), Martin Spott [EMAIL PROTECTED] wrote: Explaining in pictures is easier than dealing with single-line- equations :-) We'll see, Multiple, sequential equations are welcome as well. Anything, really ... Could you go into detail about what kind of compass/error we're talking ? The link that he gave goes into it in detail. -c -- Chris Metzler [EMAIL PROTECTED] (remove snip-me. to email) As a child I understood how to give; I have forgotten this grace since I have become civilized. - Chief Luther Standing Bear pgp3oE2zfBMM9.pgp Description: PGP signature ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
Developers, I am planing on developing a HUD instrument to display a virtual outline of the active runway on the HUD. Is there any developer(s) working on this task? If not, can anyone tell me how I can get the aircraft's velocity vector and runway vector in Cartesian coordinates. Thanks, Aaron Wilson At 04:38 PM 11/2/2004, you wrote: I just compiled the latest stable source 0.9.6 and the keyboard commands were not working. The only way I could get them to fire the binded command was to set the keys to repeatable (i.e. repeatabletrue/repeatable). Has anyone else had this problem? Thanks, Aaron I. Wilson AST: Computer Engineer TEL: (304) 367-8299 FAX: (304) 367-8203 [EMAIL PROTECTED] http://www.ivv.nasa.gov/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
Aaron Wilson wrote: Developers, I am planing on developing a HUD instrument to display a virtual outline of the active runway on the HUD. Is there any developer(s) working on this task? If not, can anyone tell me how I can get the aircraft's velocity vector and runway vector in Cartesian coordinates. Hi Aaron, Sounds like a fun project. :-) I'm not aware that any one else is doing anything like this. simgear/math/sg_geodesy.hxx has routines for converting from geodetic lon/lat/elev to earth centered cartesian coordinates. What I've done in the past is to use spherical or wgs84 routines to calculate the corner points of the runway(s) and then convert the resulting lon/lat into cartesian coordinates. This makes things much easier conceptually, but perhaps is not the most efficient approach computationally. In the FG core code, there is an abs_view_pos vector that gives you the earth centered cartesian coordinates of your view point. I believe we also have view direction in the same cartesian coordiante system. I don't know if we have the aircraft's velocity vector directly, but I'm sure you could compute it, or you could estimate it by taking cart_pos(n) - cart_pos(n-1) Once you have all that, it's simply :-) a matter of getting your view parameters set up correctly and dumping your runway verticies/lines into the opengl pipeline. Do you plan to account for sloping or hilly runways? These are found both in the real world and in FG ... and they do sometimes make life a little more difficult than we'd like. If you start fiddling with sloped runways, you might want to consider some sort of offline process to create your runway objects with the proper slope/elevation across their surface then store them in some sort of database, rather than trying to create them on the fly. I suppose the accuracy that you need for drawing your hud runways depends largely on the accuracy of your sensors, and the tolerances within which you need to fly the aircraft. If you are planning to fly all the way to touchdown with zero visibility, then you probably need to go the extra mile and account for runway slope. Regards, Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
Curtis, Thanks for the insight into the coordinate systems. I am planning on accounting for a sloped runway via the runway vector. The cross product of the aircraft's velocity vector with the runways vector (which should point in the direction of the slope) will give you a vector to rotate about and angle to rotate can be calculated from the dot product. However, the runways are only have a center point. How does does FlightGear determine the slope? More specifically how can I get the four corners of the runway with the accurate slope? Thanks, Aaron At 12:00 PM 11/3/2004, you wrote: Aaron Wilson wrote: Developers, I am planing on developing a HUD instrument to display a virtual outline of the active runway on the HUD. Is there any developer(s) working on this task? If not, can anyone tell me how I can get the aircraft's velocity vector and runway vector in Cartesian coordinates. Hi Aaron, Sounds like a fun project. :-) I'm not aware that any one else is doing anything like this. simgear/math/sg_geodesy.hxx has routines for converting from geodetic lon/lat/elev to earth centered cartesian coordinates. What I've done in the past is to use spherical or wgs84 routines to calculate the corner points of the runway(s) and then convert the resulting lon/lat into cartesian coordinates. This makes things much easier conceptually, but perhaps is not the most efficient approach computationally. In the FG core code, there is an abs_view_pos vector that gives you the earth centered cartesian coordinates of your view point. I believe we also have view direction in the same cartesian coordiante system. I don't know if we have the aircraft's velocity vector directly, but I'm sure you could compute it, or you could estimate it by taking cart_pos(n) - cart_pos(n-1) Once you have all that, it's simply :-) a matter of getting your view parameters set up correctly and dumping your runway verticies/lines into the opengl pipeline. Do you plan to account for sloping or hilly runways? These are found both in the real world and in FG ... and they do sometimes make life a little more difficult than we'd like. If you start fiddling with sloped runways, you might want to consider some sort of offline process to create your runway objects with the proper slope/elevation across their surface then store them in some sort of database, rather than trying to create them on the fly. I suppose the accuracy that you need for drawing your hud runways depends largely on the accuracy of your sensors, and the tolerances within which you need to fly the aircraft. If you are planning to fly all the way to touchdown with zero visibility, then you probably need to go the extra mile and account for runway slope. Regards, Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ATI 9200 Direct Rendering problem on Linux
Ampere K. Hardraade wrote: it seem agpgart is still seeing the i810 and not the ATI card. Did you already give the OpenSource drivers a try ? Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
Boris Koenig wrote: My first VERY simple *guess* would be that it might be because of an imbalance in inertia of a compasses moving parts as soon as the pitch changes accordingly. It has to do with the fact that a whiskey compass has it's magentic 'detector' mountet parallel to the earth magnetic field of that area where the aircraft is supposed to be operated which means the detector has some orientation that is anything but parallel to the surface: http://www.phy6.org/Education/wfldline.html When you bank the aircraft then you'll encounter that the compass does not only point to the magnetic north, adding to that the 'detector' tries to orientate parallel to the magnetic field - which doesn't matter as long as you fly straight because the compass is adjusted accordingly. This results in the turning error, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 03 Nov 2004 17:25:16 +0100, Boris Koenig [EMAIL PROTECTED] wrote: My first VERY simple *guess* would be that it might be because of an imbalance in inertia of a compasses moving parts as soon as the pitch changes accordingly. Other replies have pointed you to links explaining the turning error due to magnetic dip. It is quite dramatic in a real plane -- at my latitude (about 45 deg N), my compass can be more than 50 degrees off while the wings are banked, depending on the heading. You are correct, though, that there is also an overshoot error -- the compass will tend to overshoot and oscillate, rather than locking immediately onto a new heading. Alex already had code in place for that, and I plan to add it back in once I have the turning, pitch, and acceleration errors working. All the best, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ATI 9200 Direct Rendering problem on Linux
No. How do I do so? Ampere On November 3, 2004 12:41 pm, Martin Spott wrote: Ampere K. Hardraade wrote: it seem agpgart is still seeing the i810 and not the ATI card. Did you already give the OpenSource drivers a try ? Martin. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
Aaron Wilson wrote: Curtis, Thanks for the insight into the coordinate systems. I am planning on accounting for a sloped runway via the runway vector. The cross product of the aircraft's velocity vector with the runways vector (which should point in the direction of the slope) will give you a vector to rotate about and angle to rotate can be calculated from the dot product. However, the runways are only have a center point. How does does FlightGear determine the slope? More specifically how can I get the four corners of the runway with the accurate slope? Runways aren't just flat sloping planes though - the slope may not be constant. Several runways have a hump in the middle, or a slope at just one end. There was a mail from curt a few days ago which explained how airfields are created and laid over the terrain data. -- Jon Stockill [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 10:17:34 -0500 David Megginson [EMAIL PROTECTED] wrote: I'm fixing the magnetic compass instrument to make its behaviour more realistic. I'm starting with the northernly turning error, and found a useful site that actually gives an equation: http://williams.best.vwh.net/compass/node4.html Here's the equation (radians for all angles): Hc: indicated compass heading Hm: actual magnetic heading phi: bank angle (right positive; the original web page uses theta) mu: magnetic dip angle (down positive) Hc = atan2(sin(Hm)cos(phi) - tan(mu)sin(phi), cos(Hm)) The result is very realistic as far as bank/turning errors go, much better than anything I've seen in a desktop sim. I've checked in the changes so that others can take a look. The problem is that this equation assumes that pitch (theta) is 0. Now, I need to adapt this equation to incorporate theta as well, so that the compass will show an error when the nose is pitched up or down relative to the earth's surface. I imagine that the problem is fairly obvious to people with a basic knowledge of geometry and trig, but unfortunately, I am not one of those people. I would be very grateful for someone could reply with an adaption of the above equation integrating theta. A simple adaptation doesn't really work. Using the variables as you've defined them, and taking theta to be positive for pitched up, write Hc = atan2(a, b) with a = cos(phi)sin(Hm)cos(mu) - sin(phi)cos(theta)sin(mu) - sin(phi)sin(theta)cos(mu)cos(Hm) b = cos(theta)cos(Hm)cos(mu) - sin(theta)sin(mu) I'd appreciate it if someone would check my matrix multiplication (Euler rotations), but I'm pretty sure this is correct. It reduces to the equation you gave for the case of zero pitch (theta = 0). The way to solve this problem is to imagine not that you're changing the attitude of the plane, but that you're changing the orientation of the vector instead. So you start with the plane heading magnetic north; the plane's aligned with the B vector in the XY plane (+X = east, +Y = north) but the vector has a -Z component. Rotating the plane to a magnetic heading Hm is equivalent to rotating the XY components of the B vector counterclockwise Hm. Then pitching the plane up/down corresponds to rotating the YZ components of the vector. Then banking the plane corresponds to rotating the XZ components of the vector. You have to do it in this order. I first tried it by creating the state described on the web page you gave (plane at magnetic heading Hm, and banked). I then tried to apply the pitch. But that won't give you the right answer because pitching the plane up and down in its own reference frame won't correspond to what we call pitch since the plane is already banked. -c -- Chris Metzler [EMAIL PROTECTED] (remove snip-me. to email) As a child I understood how to give; I have forgotten this grace since I have become civilized. - Chief Luther Standing Bear pgpBGhx0JxHeH.pgp Description: PGP signature ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] Re: Plea for help: geometry/trigonometry problem
I've thought of a simpler way to approach this problem. Let's say that I have a plane and the three Euler angles of rotation, phi, theta, and psi (roll, pitch, and yaw). Given those three angles, I'd like to determine which direction around the z axis is most directly uphill and how steep the hill is. Thanks, and all the best, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ATI 9200 Direct Rendering problem on Linux
Ampere K. Hardraade wrote: On November 3, 2004 12:41 pm, Martin Spott wrote: Ampere K. Hardraade wrote: it seem agpgart is still seeing the i810 and not the ATI card. Did you already give the OpenSource drivers a try ? No. How do I do so? Install XFree86 or better XOrg from your favorite Linux distribution and adjust your 'XF86Config' or 'xorg.conf' according the exaple I've pointed at in my posting on tuesday, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
Jon Stockill wrote: Runways aren't just flat sloping planes though - the slope may not be constant. Several runways have a hump in the middle, or a slope at just one end. I believe for the purpose of outlining the runway in order to get the aircraft down in one piece it is absolutely sufficient to have an average, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
Martin Spott wrote: Jon Stockill wrote: Runways aren't just flat sloping planes though - the slope may not be constant. Several runways have a hump in the middle, or a slope at just one end. I believe for the purpose of outlining the runway in order to get the aircraft down in one piece it is absolutely sufficient to have an average, Right, the question is how far do you want to take it. Do you want to get down close enough to see the runway and finish the landing visually? Do you want to fly and land 100% blind to the real world? Maybe the original poster is remotely flying a UAV rather than a real aircraft, so transitioning to visual flight might not be an option? We did a real world project here where we developed a HUD for ground vehicles (snow plows, state patrol, and ambulances.) The HUD displayed lane boundaries and radar/laser targets, as well as other statically mapped objects such as mail boxes, guard rails, and jerzey barriers. We did a test with a state patrol car where we mapped and drove a closed loop track (Brainerd International Raceway). The drives were done 100% blind, 100% from HUD only. Our HUD system was differential gps based with an update rate of 10hz and it worked amazingly well. We used real state patrol drivers for the study and there must have been some sort of behind the scenes wager amongst themselves for who could get through the first turn the fastest because many of these guys drove insanely fast. I drove the course once, and knowing what I knew about the system and technology, I took things a *lot* slower. :-) In the end though, the system worked flawlessly, and the closest thing we had to a mishap was almost hitting a deer. Regards, Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ATI 9200 Direct Rendering problem on Linux
If you are referring the radeon driver, itI am using it at the moment and it doesn't give me direct rendering either. Ampere On November 3, 2004 03:15 pm, Martin Spott wrote: Install XFree86 or better XOrg from your favorite Linux distribution and adjust your 'XF86Config' or 'xorg.conf' according the exaple I've pointed at in my posting on tuesday, Martin. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
On Wed, 3 Nov 2004 20:17:50 + (UTC), Martin wrote in message [EMAIL PROTECTED]: Jon Stockill wrote: Runways aren't just flat sloping planes though - the slope may not be constant. Several runways have a hump in the middle, or a slope at just one end. I believe for the purpose of outlining the runway in order to get the aircraft down in one piece it is absolutely sufficient to have an average, ..aircraft usually _are_ in one piece until they hit such an average sloping area. ;-) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ATI 9200 Direct Rendering problem on Linux
Ampere K. Hardraade wrote: If you are referring the radeon driver, itI am using it at the moment and it doesn't give me direct rendering either. I have to guess what you're meaning Could you post the Device and the DRI section of your XF86Config ? Simply use cut 'n paste so I don't have to fiddle with attachments, Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ATI 9200 Direct Rendering problem on Linux
Section Device Identifier Generic Video Card Driver radeon EndSection Section Monitor Identifier SyncMaster HorizSync 30-60 VertRefresh 56-75 Option DPMS EndSection Section Screen Identifier Default Screen Device Generic Video Card Monitor SyncMaster DefaultDepth24 SubSection Display Depth 1 Modes 1024x768 800x600 640x480 EndSubSection SubSection Display Depth 4 Modes 1024x768 800x600 640x480 EndSubSection SubSection Display Depth 8 Modes 1024x768 800x600 640x480 EndSubSection SubSection Display Depth 15 Modes 1024x768 800x600 640x480 EndSubSection SubSection Display Depth 16 Modes 1024x768 800x600 640x480 EndSubSection SubSection Display Depth 24 Modes 1024x768 800x600 640x480 EndSubSection EndSection Section ServerLayout Identifier Default Layout Screen Default Screen InputDevice Generic Keyboard InputDevice Configured Mouse InputDevice Generic Mouse EndSection Section DRI Mode0666 EndSection On November 3, 2004 03:57 pm, Martin Spott wrote: I have to guess what you're meaning Could you post the Device and the DRI section of your XF86Config ? Simply use cut 'n paste so I don't have to fiddle with attachments, Martin. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Re: Plea for help: geometry/trigonometry problem
David Megginson wrote: I've thought of a simpler way to approach this problem. Let's say that I have a plane and the three Euler angles of rotation, phi, theta, and psi (roll, pitch, and yaw). Given those three angles, I'd like to determine which direction around the z axis is most directly uphill and how steep the hill is. Hmmm, that's a good mind bender ... I'm still thinking ... linear algebra was *sooo* long ago ... :-) Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ATI 9200 Direct Rendering problem on Linux
If I keep the radeon in the driver section, the config file isn't read at all. Therefore, I changed it back to ati. Ampere ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Re: Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 14:05:59 -0500 David Megginson [EMAIL PROTECTED] wrote: I've thought of a simpler way to approach this problem. Let's say that I have a plane and the three Euler angles of rotation, phi, theta, and psi (roll, pitch, and yaw). Given those three angles, I'd like to determine which direction around the z axis is most directly uphill and how steep the hill is. For JSBSim, the order of rotation is z, y, x (heading, pitch, roll). Given that, note that pitch and roll don't affect heading. I assume you are talking about the aircraft z axis in your last sentence. Also, I assume that you mean, which angle about the z axis is most vertical with respect to the local horizontal? I _think_ this answer might have something to do with constructing an omega rotation vector using the Euler angles, transforming it to the local frame, and taking a dot product, but I'd have to think about this one for a little bit. This is kind of a cool problem. Probably someone else will have figured this out by the time I post this email ... :-) Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Re: Plea for help: geometry/trigonometry problem
David Megginson wrote: I've thought of a simpler way to approach this problem. Let's say that I have a plane and the three Euler angles of rotation, phi, theta, and psi (roll, pitch, and yaw). Given those three angles, I'd like to determine which direction around the z axis is most directly uphill and how steep the hill is. Thanks, and all the best, David I'm sitting here wiggling a cd around and thinking ... If you roll the cd only, the highest point on the disk will be straight out the left/right side depending on the roll direction. If you pitch the cd only, the highest point on the disk will be straight out the front/back depending on the pitch direction. It *seems* like if you combine roll and pitch, the highest point on the cd/disk will be a combination of the roll and pitch amounts ... perhaps simple trig functions would apply here, but that's based on shakey intuition only. The vertical component of disk edge movement is relative to sin(angle), if you pitch and roll identical amounts, then your highest point is at a 45 degree offset which seems to fall in line. Now playing fast and loose, what if you look straight down on a disk ... +X is up, +Y is right, just a standard 2d cartesian system. Now map the amount of roll to X and the amount of pitch to Y. The highest point on the disk should be x = sin(roll)*cos(pitch), y = cos(roll)*sin(pitch) and there's probably a - sign that goes in there someplace. I'm not sure if we can get away with directly mappy roll to X and pitch to Y ... might need some sort of trig function of roll/pitch to get X, Y? Then it seems like you could take the answer you get when isolating roll/pitch and add in the heading as an offset ... of course that would be dependant on the order your euler angles are designed to be multipled ... Once you have the most upward pointing vector on the surface of the disk, then it's easy to find the angle with horizontal. Project the most upward pointing vector onto a flat plane, and then figure out the angle between the projected vector and the original vector ... I'm probably way off here, but maybe this will spark someone else's brain cells to figure out the right way to do this ... Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Re: Plea for help: geometry/trigonometry problem
On Wed, 03 Nov 2004 15:28:26 -0600 Curtis L. Olson [EMAIL PROTECTED] wrote: I think you're on the right track. I think you want to determine the orientation of the aircraft body Z axis w.r.t. the local vertical axis. That can tell you both the magnitude and direction of the most vertical ascent about the local vertical axis. Geez ... yes, it has been a long time ... :-) Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 14:04:05 -0500, Chris Metzler [EMAIL PROTECTED] wrote: A simple adaptation doesn't really work. Using the variables as you've defined them, and taking theta to be positive for pitched up, write Hc = atan2(a, b) with a = cos(phi)sin(Hm)cos(mu) - sin(phi)cos(theta)sin(mu) - sin(phi)sin(theta)cos(mu)cos(Hm) b = cos(theta)cos(Hm)cos(mu) - sin(theta)sin(mu) Thanks for all the work on that. I just tried it out, though, and it gives strange behaviour with negative (left) roll angles, even when pitch is close to 0. It's possible that I caused some confusion by using theta for pitch, when the original equation used it for roll -- here's the original equation from the Web page, translated into our normal phi/theta/psi variables, mu for magnetic dip, and preserving Hc for the indicated compass heading: Hc = atan2(sin(psi)cos(phi) - tan(mu)sin(phi), cos(psi)) In other words a = sin(psi)cos(phi) - tan(mu)sin(phi) b = cos(psi) Your suggested equation, using the same variable names, is a = cos(phi)sin(psi)cos(mu) - sin(phi)cos(theta)sin(mu) - sin(phi)sin(theta)cos(mu)cos(psi) b = cos(theta)cos(psi)cos(mu) - sin(theta)sin(mu) I'm really bad at this kind of thing, but when I set theta to 0, I end up with a = cos(phi)sin(psi)cos(mu) - sin(phi)sin(mu) b = cos(psi)cos(mu) Does that actually work out to the same thing by messing around with the trig? Thanks, and all the best, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 16:47:37 -0500 David Megginson [EMAIL PROTECTED] wrote: What does arctan(-phi/theta) give you? Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 16:47:37 -0500 David Megginson [EMAIL PROTECTED] wrote: After having scribbled for a LITTLE WHILE on the back of an envelope ;-) I am thinking that what you want is this: -atan2(-phi,theta) but I'll have to play a little bit more. I think this would give you the angle about the local vertical from the aircraft X axis to the most vertical ascent angle given the plane located by the aircraft X and Y axes. Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 03 Nov 2004 16:02:19 -0600, Jon S Berndt [EMAIL PROTECTED] wrote: After having scribbled for a LITTLE WHILE on the back of an envelope ;-) I am thinking that what you want is this: -atan2(-phi,theta) but I'll have to play a little bit more. I think this would give you the angle about the local vertical from the aircraft X axis to the most vertical ascent angle given the plane located by the aircraft X and Y axes. I put it in a Perl script and played with it for different values of phi and theta, and all of the results looked reasonable. Now, how can I calculate the most vertical ascent angle itself? Thanks, and all the best, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 16:47:37 -0500 David Megginson [EMAIL PROTECTED] wrote: Thanks for all the work on that. I just tried it out, though, and it gives strange behaviour with negative (left) roll angles, even when pitch is close to 0. It's possible that I caused some confusion by using theta for pitch, when the original equation used it for roll -- here's the original equation from the Web page, translated into our normal phi/theta/psi variables, mu for magnetic dip, and preserving Hc for the indicated compass heading: Hc = atan2(sin(psi)cos(phi) - tan(mu)sin(phi), cos(psi)) In other words a = sin(psi)cos(phi) - tan(mu)sin(phi) b = cos(psi) Your suggested equation, using the same variable names, is a = cos(phi)sin(psi)cos(mu) - sin(phi)cos(theta)sin(mu) - sin(phi)sin(theta)cos(mu)cos(psi) b = cos(theta)cos(psi)cos(mu) - sin(theta)sin(mu) I'm really bad at this kind of thing, but when I set theta to 0, I end up with a = cos(phi)sin(psi)cos(mu) - sin(phi)sin(mu) b = cos(psi)cos(mu) Does that actually work out to the same thing by messing around with the trig? Yes, it does. Basically, just leave the cos(psi) in the denominator, and divide the cos(mu) that's in the denominator into a. In other words, cos(phi)sin(psi)cos(mu) - sin(phi)sin(mu) - cos(psi)cos(mu) = cos(phi)sin(psi)cos(mu)sin(phi)sin(mu) ---- --- cos(psi)cos(mu) cos(psi)cos(mu) (in the first term, cancel out the cos(mu) in the numerator and denominator; in the second term, take the sin(mu)/cos(mu) and replace it with a tan(mu) in the numerator) = cos(phi)sin(psi) sin(phi)tan(mu) - --- cos(psi) cos(psi) = (cos(phi)sin(psi) - sin(phi)tan(mu))/cos(psi) which is what you have above. So yeah, it does work out. I'll check my algebra again, but what are the chances that the strange behavior (you didn't describe what it was) you're seeing are numerical? In other words, when it occurs, what's the typical value of the argument of the arctan? -c -- Chris Metzler [EMAIL PROTECTED] (remove snip-me. to email) As a child I understood how to give; I have forgotten this grace since I have become civilized. - Chief Luther Standing Bear pgprkfqCL2EnT.pgp Description: PGP signature ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 03 Nov 2004 16:02:19 -0600 Jon S Berndt [EMAIL PROTECTED] wrote: On Wed, 3 Nov 2004 16:47:37 -0500 David Megginson [EMAIL PROTECTED] wrote: After having scribbled for a LITTLE WHILE on the back of an envelope ;-) I am thinking that what you want is this: -atan2(-phi,theta) Maybe I am missing what you are trying to do, but I just tried this in Excel: -atan2(theta,phi) which gives this: theta phi angle (from forward, positive clockwise) 45 0 0 45 -45 45 0 -45 90 -45 -45 135 -45 0 -180 -45 45 -135 0 45 -90 45 45 -45 0 0 BAD! 10 0 0 10 80 -82.87498365 80 10 -7.125016349 ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
David Megginson wrote: On Wed, 03 Nov 2004 16:02:19 -0600, Jon S Berndt [EMAIL PROTECTED] wrote: After having scribbled for a LITTLE WHILE on the back of an envelope ;-) I am thinking that what you want is this: -atan2(-phi,theta) but I'll have to play a little bit more. I think this would give you the angle about the local vertical from the aircraft X axis to the most vertical ascent angle given the plane located by the aircraft X and Y axes. I put it in a Perl script and played with it for different values of phi and theta, and all of the results looked reasonable. Now, how can I calculate the most vertical ascent angle itself? 1. a plane in the geometrical sense can be defined with a point and a vector that is perpedicular to that plane. Define a plane by picking your current location as the point, and pick the local up vector (opposite of the gravity vector) as your perpendicular vector. 2. define a vector as the x,y,z distances to the highest point on your rotated/pitched/yawed disk (which appears to be calculated with the atan2() formula above. 3. simgear/math/vector.hxx defines a function that maps/projects the vector from (2) onto the plane from (1) sgmap_vec_onto_cur_surface_plane() returning the mapped/projected vector as the result. Now you have a vector that lies on your horizontal plane, and a vector to your highest elevation point. All you need to do is find the angle between the two which off the top of my head is the arcsin of the dot product of the two vectors (probably normalized.) My linear algebra book is at home so this is all off the top of my head. Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 03 Nov 2004 16:17:24 -0600, Jon S Berndt [EMAIL PROTECTED] wrote: Maybe I am missing what you are trying to do, but I just tried this in Excel: -atan2(theta,phi) which gives this: theta phi angle (from forward, positive clockwise) 45 0 0 45 -45 45 0 -45 90 -45 -45 135 -45 0 -180 -45 45 -135 0 45 -90 45 45 -45 0 0 BAD! 10 0 0 10 80 -82.87498365 80 10 -7.125016349 Those look pretty reasonable for offsets from the aircraft's current heading. For example, if you're at 0 pitch a 45 degree right bank, uphill will be 90 degrees to the left of your current heading (-90). If you're pitched down 45 degrees and banked 45 degrees to the right, uphill will be 135 degrees to the left of your current heading; and so on. All the best, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Key Bindings
Martin Spott wrote: Jon Stockill wrote: Runways aren't just flat sloping planes though - the slope may not be constant. Several runways have a hump in the middle, or a slope at just one end. I believe for the purpose of outlining the runway in order to get the aircraft down in one piece it is absolutely sufficient to have an average, Right, the question is how far do you want to take it. Do you want to get down close enough to see the runway and finish the landing visually? Do you want to fly and land 100% blind to the real world? Maybe the original poster is remotely flying a UAV rather than a real aircraft, so transitioning to visual flight might not be an option? We did a real world project here where we developed a HUD for ground vehicles (snow plows, state patrol, and ambulances.) The HUD displayed lane boundaries and radar/laser targets, as well as other statically mapped objects such as mail boxes, guard rails, and jerzey barriers. We did a test with a state patrol car where we mapped and drove a closed loop track (Brainerd International Raceway). The drives were done 100% blind, 100% from HUD only. Our HUD system was differential gps based with an update rate of 10hz and it worked amazingly well. We used real state patrol drivers for the study and there must have been some sort of behind the scenes wager amongst themselves for who could get through the first turn the fastest because many of these guys drove insanely fast. I drove the course once, and knowing what I knew about the system and technology, I took things a *lot* slower. :-) In the end though, the system worked flawlessly, and the closest thing we had to a mishap was almost hitting a deer. Regards, Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 17:19:09 -0500 Chris Metzler [EMAIL PROTECTED] wrote: I'll check my algebra again, Checked; I can't find a mistake. As a third check, I ran it through Maple and got the same result. It appears to have the correct limiting behavior for both pitch -- 0 and roll -- 0 independently. And the problem seems straightforward to me. The compass needle is constrained to move on the horizontal plane in the aircraft's reference frame; the question is simply what's the (perpendicular) projection of the magnetic field vector onto that plane, and what direction does that point? You can move the plane by from level flight towards the north pole by yaw, then pitch, then roll; or you can do the opposite transformations on the magnetic field vector itself (same order, but opposite value of angles), and get the same relative orientation of the field vector to the aircraft. So I think this is analytically correct. What's the weird behavior? For what part of parameter space? -c -- Chris Metzler [EMAIL PROTECTED] (remove snip-me. to email) As a child I understood how to give; I have forgotten this grace since I have become civilized. - Chief Luther Standing Bear pgpWXAX5R5Qip.pgp Description: PGP signature ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
More: theta phi heading magnitude 45.00 0.000.0045.00 45.00 -45.00 45.0075.00 0.00 -45.00 90.0045.00 -45.00 -45.00 135.0075.00 -45.00 0.00 -180.0045.00 -45.00 45.00 -135.0075.00 0.00 45.00 -90.0045.00 45.00 45.00 -45.0075.00 45.00 0.000.0045.00 Not sure if this is really true, cause I have not yet figured out by longhand the ascent angle at 45/45 degrees, but it looks close if not right. The heading (as stated before) is: -ATAN2(theta,phi) The ascent angle magnitude is (where theta and phi are supplied in radians): 1.57 - ACOS(COS(theta)*(SIN(ABS(phi + ABS(theta) This might be able to be cleaned up considerably. Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] Re: Plea for help: geometry/trigonometry problem
David Megginson writes: I've thought of a simpler way to approach this problem. Let's say that I have a plane and the three Euler angles of rotation, phi, theta, and psi (roll, pitch, and yaw). Given those three angles, I'd like to determine which direction around the z axis is most directly uphill and how steep the hill is. see sgEulerToQuat( sgQuat quat, const sgVec3 hpr ) ; HTH Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Plea for help: geometry/trigonometry problem
On Wed, 3 Nov 2004 20:16:08 -0500, David Megginson [EMAIL PROTECTED] wrote: I understand, logically, why this is happening: flying west with a magnetic dip of 71 and a bank of 20 to the south, I have an angle of over 90 degrees to the magnetic flow. I think I even remember the original article mentioning something like this, but I have no recollection of my airplane whiskey compass swinging around 180 degrees suddenly in real life -- if there's a window tomorrow before the low icing stuff moves in, I'll try to go up and take a look at what actually happens. To answer myself, here's the relevant part of the original web page: ==**== For steep turns, where the sum of the dip angle and bank angle exceeds 90 degrees, the compass will ``hang up''. The compass will refuse to turn through 360 degrees as the airplane makes a complete circle. It's easy to see why. Imagine being on a heading of East in the Northern hemisphere, and gradually increasing bank angle to the right. Initially, the north seeking end of the compass needle will point exactly North, towards the left wing tip. However, as the bank angle increases, a point is reached where the magnetic field becomes parallel to the airplane's vertical axis. Beyond this point, the compass needle will swing 180 degrees to point to the lower, right wingtip and the compass then indicates West instead of East! So it is not quite true to say there is no Northerly turning error on headings of East and West. Beyond the critical bank angle (equal to 90 minus the dip angle), the compass lags by 180 degrees when the airplane is banked toward the equator. ==**== Obviously, when the dip is over 70 degrees, it doesn't take a steep turn to cause this effect. The question is, does the compass hang up (i.e. bind and refuse to turn), or does it swing around? If it hangs up, that would explain why I haven't noticed the effect. Any comments from other pilots on the list, especially those who fly north of 40 in North America? Thanks, and all the best, David -- http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] Plea for help: geometry/trigonometry problem
Oops. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] RE: [Not-so-OFFLINE] Plea for help:geometry/trigonometry problem
On Wed, 3 Nov 2004 19:40:57 -0600, Jon Berndt [EMAIL PROTECTED] wrote: Well, I don't know if my calculations helped any, but it sure was a fun diversion for a little while ... Since Jon accidentally went online with this, I'd like to thank him for the work. It turned out that I didn't need to add the extra steps (that I had asked for before seeing Chris's equation). Thanks, David Heh. You're welcome. :-) I didn't see Chris's work 'til after I had finished up. If I had, I probably wouldn't have tried - but glad I did. Whether I was correct or not, it was fun. Now for my next trick: well-formed XML parsing changes in JSBSim ... Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Multiheaded video cards?
Curtis L. Olson wrote: I periodically get asked about multiheaded video cards for FlightGear. My standard answer is that I don't know for sure, but I suspect they wouldn't work well for FlightGear. However, the questions keep coming and I feel like I'm not able to give a really good answer. So can anyone help me out? For instance, has anyone tried one of these sorts of cards? http://www.matrox.com/mga/products/parhelia/series.cfm I was looking into these by my slush fund died a sudden death. :( What kind of opengl support is available under linux? I run a Matrox G450 in the dual-head configuration. The primary channel has the acceleration. If you run glxgears on both displays, the secondary display outperforms the primary. If you run fgfs on both, the secondary display almost stops and the primary display alternates between smooth flight and very slooow. The dual headed G450 would be great for a primary display and an instructors display or for groking code while flying the sim. The GL stuff works great within limits. Here is the performance I get (primary display only): (fgfs-cvs --hud-tris ) night 160fps steep circling turn over airport, 300fps level flight away from airport noon 11fps steep circling turn over airport, 30fps level flight away from airport I don't have a clue if these values are good or bad, but it's what FGFS reports. The Matrox card support is minimal but it works great for me. I run two 20' monitors side-by-side and the GL stuff is always on the primary. Anything can go on the secondary but GL will kill performance of both displays. Don't, but, don't us Xinerama as it is non-accelerated and generally a pain. Has anyone played around with any of these options who can report success or failure or something in between? What kind of performance are you getting? Thanks, Curt. Dale ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Multiheaded video cards?
Chris Metzler wrote: On Tue, 02 Nov 2004 12:37:40 -0600 Curtis L. Olson [EMAIL PROTECTED] wrote: I periodically get asked about multiheaded video cards for FlightGear. My standard answer is that I don't know for sure, but I suspect they wouldn't work well for FlightGear. However, the questions keep coming and I feel like I'm not able to give a really good answer. So can anyone help me out? For instance, has anyone tried one of these sorts of cards? http://www.matrox.com/mga/products/parhelia/series.cfm What kind of opengl support is available under linux? I haven't used these cards. However, the card I used before the one I have now was the immediate predecessor to the Parahelia, the Matrox Millenium G550. It was equipped for multihead, but I never used it. What I can tell you, though, is that DRI and OpenGL support for Matrox cards under Linux sucks rocks. First of all, Matrox' drivers are open, and their proprietary HAL module doesn't really buy you anything, so No real arguments here, but there is useable code for the card in the native X11. for just a taste. There's a lot more there too. Personally, I had constant hard lockups requiring a full system reset, with lots of DMA idle timeout messages to my X log, whenever I tried flightgear for very long with the Matrox card. From other messages in the Matrox Sounds like the ASUS (junk!) motherboard I had. My 1GHz athalon on its ASUS board sits collecting dust (it doesn't even do that very well). The G450 I have is very robust as is the code. I run Debian Linux without a single lockup in over a year now. The ASUS with a simple ATI GL card still locks up. What a waste of silicon! Dale ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
