DJTN

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About DJTN

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  1. Float Precision Issue?

    [quote name='Madhed' timestamp='1353361755' post='5002455'] Honestly, to me it sounds like you are overanalyzing the "problem". I never encountered anything along those lines that was really noticeable and without seeing this myself I can't imagine what the problem actually looks like. Are you sure the wrong motion isn't caused by something else? [/quote] I've stripped my code down to nothing more than a camera and one object being rendered. I'm not overanalyzing the "problem". If the camera's rotations are not smooth, they are not smooth. Some might be ok with a randomly jerking camera, I'm not one of those people. Thanks? I'll revisit this at a later time.
  2. Float Precision Issue?

    Wow, I'm running out of ideas here. Since my View Matrix is accumalitive (I never reset my axis) - could this be the problem? I update every frame using the D3DXMatrixLookAtLH to build the View Matrix. My camera's Up never changes, only the position and the target.
  3. Float Precision Issue?

    [quote name='Hodgman' timestamp='1353205339' post='5001917'] Shouldn't it be 6.283....? [/quote] Yes Hodge, you're correct. I was truncating the float in my code to gain precision. [quote name='C0lumbo' timestamp='1353227105' post='5001982'] Another thing that occurs to me is that if your CameraPosition vector was a long way from the origin, then there'd be a lot of error when you create your CameraTarget vector by adding the unit vector, which could explain some oddness. Could you check that's not the case? [/quote] My camera position is (0,8,0). My target is (1,8,0) at the start. When I break on the code after the first value of 0.003 for hRadians has been calculated the target becomes (0.9999955, 8, 0.002999996) with the position vector staying the same. The target for the next 90+ frames: Frame: 0 Target: (1 , 8 , 0) Frame: 1 Target: (0.9999955 , 8 , 0.002999996) Frame: 2 Target: (0.999982 , 8 , 0.005999964) Frame: 3 Target: (0.9999595 , 8 , 0.008999879) Frame: 4 Target: (0.999928 , 8 , 0.01199971) Frame: 5 Target: (0.9998875 , 8 , 0.01499944) Frame: 6 Target: (0.999838 , 8 , 0.01799903) Frame: 7 Target: (0.9997795 , 8 , 0.02099846) Frame: 8 Target: (0.999712 , 8 , 0.0239977) Frame: 9 Target: (0.9996355 , 8 , 0.02699672) Frame: 10 Target: (0.99955 , 8 , 0.0299955) Frame: 11 Target: (0.9994556 , 8 , 0.03299401) Frame: 12 Target: (0.9993521 , 8 , 0.03599223) Frame: 13 Target: (0.9992396 , 8 , 0.03899011) Frame: 14 Target: (0.9991181 , 8 , 0.04198765) Frame: 15 Target: (0.9989877 , 8 , 0.04498481) Frame: 16 Target: (0.9988482 , 8 , 0.04798157) Frame: 17 Target: (0.9986998 , 8 , 0.05097789) Frame: 18 Target: (0.9985424 , 8 , 0.05397375) Frame: 19 Target: (0.998376 , 8 , 0.05696913) Frame: 20 Target: (0.9982005 , 8 , 0.059964) Frame: 21 Target: (0.9980162 , 8 , 0.06295833) Frame: 22 Target: (0.9978228 , 8 , 0.06595208) Frame: 23 Target: (0.9976205 , 8 , 0.06894525) Frame: 24 Target: (0.9974091 , 8 , 0.0719378) Frame: 25 Target: (0.9971888 , 8 , 0.07492969) Frame: 26 Target: (0.9969596 , 8 , 0.07792092) Frame: 27 Target: (0.9967213 , 8 , 0.08091144) Frame: 28 Target: (0.9964741 , 8 , 0.08390123) Frame: 29 Target: (0.9962179 , 8 , 0.08689027) Frame: 30 Target: (0.9959527 , 8 , 0.08987853) Frame: 31 Target: (0.9956786 , 8 , 0.09286598) Frame: 32 Target: (0.9953955 , 8 , 0.09585259) Frame: 33 Target: (0.9951035 , 8 , 0.09883834) Frame: 34 Target: (0.9948025 , 8 , 0.1018232) Frame: 35 Target: (0.9944926 , 8 , 0.1048071) Frame: 36 Target: (0.9941736 , 8 , 0.1077901) Frame: 37 Target: (0.9938458 , 8 , 0.1107722) Frame: 38 Target: (0.9935091 , 8 , 0.1137532) Frame: 39 Target: (0.9931633 , 8 , 0.1167332) Frame: 40 Target: (0.9928086 , 8 , 0.1197122) Frame: 41 Target: (0.9924451 , 8 , 0.1226901) Frame: 42 Target: (0.9920725 , 8 , 0.1256668) Frame: 43 Target: (0.9916911 , 8 , 0.1286425) Frame: 44 Target: (0.9913006 , 8 , 0.131617) Frame: 45 Target: (0.9909014 , 8 , 0.1345903) Frame: 46 Target: (0.9904931 , 8 , 0.1375624) Frame: 47 Target: (0.9900759 , 8 , 0.1405333) Frame: 48 Target: (0.9896499 , 8 , 0.1435029) Frame: 49 Target: (0.989215 , 8 , 0.1464712) Frame: 50 Target: (0.9887711 , 8 , 0.1494382) Frame: 51 Target: (0.9883183 , 8 , 0.1524038) Frame: 52 Target: (0.9878566 , 8 , 0.1553681) Frame: 53 Target: (0.9873861 , 8 , 0.1583309) Frame: 54 Target: (0.9869066 , 8 , 0.1612924) Frame: 55 Target: (0.9864184 , 8 , 0.1642524) Frame: 56 Target: (0.9859211 , 8 , 0.1672109) Frame: 57 Target: (0.9854151 , 8 , 0.1701679) Frame: 58 Target: (0.9849001 , 8 , 0.1731234) Frame: 59 Target: (0.9843763 , 8 , 0.1760773) Frame: 60 Target: (0.9838437 , 8 , 0.1790297) Frame: 61 Target: (0.9833022 , 8 , 0.1819804) Frame: 62 Target: (0.9827518 , 8 , 0.1849295) Frame: 63 Target: (0.9821926 , 8 , 0.1878769) Frame: 64 Target: (0.9816245 , 8 , 0.1908226) Frame: 65 Target: (0.9810476 , 8 , 0.1937666) Frame: 66 Target: (0.980462 , 8 , 0.1967089) Frame: 67 Target: (0.9798674 , 8 , 0.1996494) Frame: 68 Target: (0.979264 , 8 , 0.2025881) Frame: 69 Target: (0.9786519 , 8 , 0.205525) Frame: 70 Target: (0.9780309 , 8 , 0.20846) Frame: 71 Target: (0.9774011 , 8 , 0.2113932) Frame: 72 Target: (0.9767625 , 8 , 0.2143244) Frame: 73 Target: (0.9761152 , 8 , 0.2172538) Frame: 74 Target: (0.975459 , 8 , 0.2201811) Frame: 75 Target: (0.9747941 , 8 , 0.2231065) Frame: 76 Target: (0.9741204 , 8 , 0.2260299) Frame: 77 Target: (0.9734379 , 8 , 0.2289513) Frame: 78 Target: (0.9727467 , 8 , 0.2318705) Frame: 79 Target: (0.9720467 , 8 , 0.2347877) Frame: 80 Target: (0.9713379 , 8 , 0.2377028) Frame: 81 Target: (0.9706205 , 8 , 0.2406158) Frame: 82 Target: (0.9698942 , 8 , 0.2435265) Frame: 83 Target: (0.9691593 , 8 , 0.2464351) Frame: 84 Target: (0.9684156 , 8 , 0.2493415) Frame: 85 Target: (0.9676632 , 8 , 0.2522456) Frame: 86 Target: (0.9669021 , 8 , 0.2551475) Frame: 87 Target: (0.9661323 , 8 , 0.258047) Frame: 88 Target: (0.9653539 , 8 , 0.2609442) Frame: 89 Target: (0.9645667 , 8 , 0.2638391) Frame: 90 Target: (0.9637709 , 8 , 0.2667316) Frame: 91 Target: (0.9629663 , 8 , 0.2696217) Frame: 92 Target: (0.9621531 , 8 , 0.2725094) Frame: 93 Target: (0.9613312 , 8 , 0.2753946) Frame: 94 Target: (0.9605008 , 8 , 0.2782773) Frame: 95 Target: (0.9596616 , 8 , 0.2811576) Frame: 96 Target: (0.9588138 , 8 , 0.2840353) Frame: 97 Target: (0.9579574 , 8 , 0.2869104) Frame: 98 Target: (0.9570924 , 8 , 0.289783)
  4. Float Precision Issue?

    [quote name='Tispe' timestamp='1353192742' post='5001869'] How about D3DXToRadian() and use 0-360 values? [/quote] A lot of overhead making that change. I'll need to figure out a way I cant test it before going all the way.
  5. Float Precision Issue?

    [quote name='C0lumbo' timestamp='1353183191' post='5001830'] What is the absolute value of hRadians? [/quote] hRadians is set to zero and 0.002 is added each frame. 6.0 in hRadians is a complete circle. It doesn't appear to be related with the inaccuracies coming from the distance from zero.
  6. Float Precision Issue?

    [quote name='Madhed' timestamp='1353184067' post='5001832'] How exactly do you increase hRadians? If you add a constant amount every frame, the rotation will of course accelerate/decelerate depending on the frame rate. [/quote] I've removed the easing (dampening) code as well as the addition of the timestamp each frame so that I can get to the bottom of the issue. Basically my render loop is just adding 0.002 to hRadians and creating the view matrix. This slowly turns the camera. When I slow the frame rate down in the debugger I can clearly see the ratation is different each frame. Some frames the rotation amount is more obvious than others.
  7. Float Precision Issue?

    [quote name='C0lumbo' timestamp='1353183191' post='5001830'] What are those trig functions you're using - do they map to sinf/cosf? What is the absolute value of hRadians? Do you reset it back to the zero to 2Pi range or to the -PI to PI range after it leaves it? (if you let a float get too far from zero the precision drops significantly). [/quote] Yes they are sinf and cosf, the code is pseudo code from memory, I'm not at my computer. hRadians starts out at 0 and I'm adding 0.002 to it every frame in an attempt to find the problem. It accumulative I do not set it back to zero. When I get home I'll check to see how I can implement locking it down to as close to zero as I can get and see if that helps.
  8. Previously I posted about a rotation issue with my camera. I thought I had solved the problem by adding frame time to the camera’s movement calculation but unfortunately this only masked the real problem, which I think is a precision issue with floats. I noticed this when I rotate not only the camera but other objects as well. I striped my render code down to the basics in an effort to identify the issue: [source lang="cpp"]Camera Calculations CameraTarget.X = CameraPosition.X + Sin(vRadians) CameraTarget.Y = CameraPosition.Y + (Cos(vRadians) * Cos(hRadians)) CameraTarget.Z = CameraPosition.Z + (Cos(vRadians) * Sin(hRadians)) CameraUp.X = 0; CameraUp.Y = 1; CameraUp.Z = 0; Update View Matrix: D3DXMatrixLookAtLH(View_Matrix, CameraPosition, CameraTarget, CameraUp); [/source] To make things as simple as possible I’ll add 0.002 to the hRadians float each frame. This makes the camera rotate to the left but when I slow the frame rate down I can clearly see the camera is not turning the same amount each frame. This also happens when I calculate rotations for the world matrix before rendering 3D objects too. When rendering at 60 FPS and adding an easing calculation to movements it’s not as noticeable for moving forward, backwards, left and right but when rotating, it is very noticeable. Even with the easing code added you can tell the rotations are accelerating and decelerating, sometimes jerky. I’ve tried to truncate the calculations for the CameraTarget and CameraPosition to regain some precision but to no avail, the issue still persists. Is this a precision issue? And if so, how can I get more precision for rotations? If it’s a not a precision problem then what is it?
  9. Thanks for the replies, I’ve since fixed my issue. My render loop checked for window’s messages and bailed the loop until the message queue was empty and then picked back up again. This normally resulted in one frame being dropped every so often- depending on the end user’s key input. The random jittering (stuttering) resulted from measuring the length of the render inside the loop and not taking the dropped frames for processing the windows messages into consideration when moving objects. Since I’ve added the timestamp to include the time it takes to clear the message queue, I’m able to smooth out the animation so it’s not noticeable. In most cases the ultimate solution would be to use DirectInput to process peripheral communications. In my situation, DirectInput is not an optimal choice. Thanks again for everyone’s input. Cheers, Dj
  10. [quote name='eppo' timestamp='1351678074' post='4995772'] you're not using a valid enumerated swapchain discription [/quote] @eppo - I'm rendering in window mode in DX9 using Discard as the swapeffect and only the implicit swapchain. [quote name='Hodgman' timestamp='1351678375' post='4995774'] How do you get your user-input values in order to rotate the camera? Is it possible that the user-input code is causing your frame-rate issues? [/quote] @Hodgman - I think you're on to something here. The movement of my camera is additive, meaning the end user can constantly pass data in. My render loop bails for the window's message queue when there are items that need to be processed. This would explain the delay / lag / FR drop. Any advice Hodg?
  11. I’ve got an issue where my camera jitters when I rotate left or right. It’s random so pinpointing the problem has been difficult. Using PIX I can see that there is a drop in frame rate when the jittering occurs. It’s not a constant jitter it’s like a frame or 2 are randomly taking longer to render. Right afterwards there is a jump in frame rate according to PIX but since I lock my FPS to 60 in my render loop I do not notice the upswing. What is even more peculiar is that I don’t have to render anything to reproduce the issue. Just the camera in the world, no mesh, no sky, etc and when I rotate left or right, randomly the frame rate dips. If I don’t VSync and I don’t lock my FPS down the jittering (lag) is more noticeable. I don’t see an issue moving forward or backwards, only rotating. I have a damping mechanism in place for my camera movement. I thought it might be the culprit so I removed everything in my camera class except the rotation’s calculations. I’m not at my desk so this is pseudo code: [CODE] CameraTarget.X = CameraPosition.X + (radius * Sin(vRadians)) CameraTarget.Y = CameraPosition.Y + (radius * Cos(vRadians) * Cos(hRadians)) CameraTarget.Z = CameraPosition.Z + (radius * Cos(vRadians) * Sin(hRadians)) CameraUp.X = CameraPosition.X – CameraTarget.X CameraUp.Y = ABS(CameraPosition.Y + (radius * Sin(vRadians + PI / 2))) CameraUp.Z = CameraPosition.Z – CameraTarget.Z [/CODE] After removing the damping code the issue still remains. It’s also worth noting that in PIX I do not have any memory or thread changes. Any input would be greatly appreciated. Dj
  12. I have an object that I would usually move by adding to its position vector. If I wanted to move it forward, I’d add to its position vector’s Z value. If I want to move it backward, I’d “subtract” from its Z value and so on. I'm in a situation now were I need to move the object forward based on the camera’s looking direction. If the camera is looking left then I need to subtract from the objects position vector’s X value, etc... To calculate the position, I thought I’d simply put the position of the object into a new vector3, add to it’s z value like before, and then transform that vector by the view matrix and then set the object's position vector to the new vector3- however, this is not working as expected. How can I transform my move (position) vector based off the camera’s looking direction?
  13. [quote name='davis31' timestamp='1345126854' post='4970183'] That would work. But is it possible to use different techniques, for the different RT when using MRT?? If it is possible, could you give an example or a resource explaining how to do that? I've not been able to find any :S [/quote] [quote name='pcmaster' timestamp='1345190278' post='4970460'] You cannot have different effects (nor techniques (nor passes)) for the individual parts of the MRT, of course. Not even in DX11. Am I right? [/quote] I should have been more specific, when I said RT's... I meant "RT" not "MRT". This would require multiple passes for each RT (surface). I assumed you knew that you cannot render MRT's with multiple effects, multiple techniques, different bit depth, different width, different height, etc... in dx9 with MRT's. MRT (Multiple Render Targets) = one pass. Multiple RT's (several separate Render Targets) = multiple passes. I apologize if I confused anyone...
  14. Reverse Reprojection

    I've never used it nor do I know of any games that use it. You'd think it would be more popular because if you cach correctly, you don't have to render new data every frame and everything can be calculated per vertex not at the pixel level. All this adds up to a faster framerate for shadows, motion blurs and DOF. There has to be a caveat somewhere.