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| (...) I mean swap the OFF-diagonals, leave the diagonals as is. (...) (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: how does a line ends?
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| (...) Interesting. I looked at the C runtime library sources that came with MSVC++ 6.0. The fgets() function there is definitely a little different than either yours or the one ROSCO linked. It does have a couple calls for thread safety, but (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: Inverse matrix?
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| (...) Just take the transpose of the 3x3 world rotation matrix and it should work as the inverse. Transpose means swap diagonals M[1,2] <=> M[2,1] etc. If this doesn't work I've misunderstood you. Tim (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: Inverse matrix?
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| (...) Hehehe, cool, I'll try that. Thanks! James (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: Inverse matrix?
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| Clarification! .... snip (...) I am using additional points to specify the location of feet. Combined with the model location, I have 3 points for the hip and feet. [now the following paragraph should make more sense] (...) (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: Inverse matrix?
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| (...) Arg. I thought this was going to be easy. I liked this part of the wikipedia article: "In practice, inverting a matrix is rarely required. Most of the time, one is really after the solution of a particular system of linear equations." Hm. I (...) (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: how does a line ends?
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| (...) Thanks, ROSCO. I took that code and modified it to use char instead of _TCHAR, and got timings of 720-750ms, compared to the 750-780ms I got with my original one. I then modified it to support CR and LF interchangeably, and got back to the (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: Inverse matrix?
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| (...) I just realised something... do you want a general inverse or a specific inverse? Some inversions are simple eg. a pure rotation can be inverted by taking its transpose and reflections are their own inverses. Tim (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: how does a line ends?
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| (...) Just as a proof of the value of disk caching, loading the same model using the system fgets after a fresh reboot, the same loading portion took 3300ms. Also, I switched the feof calls out for a check of the value against EOF just to see if it (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: how does a line ends?
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| (...) (URL) Google to the rescue>. ROSCO (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: how does a line ends?
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| (...) Quick question. I was in a hurry, and wanted to play it safe, so I call feof instead of checking to see if char1 == EOF. Any idea what gets returned for extended ASCII characters (>= 128)? Does the int contain positive numbers greater than (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: how does a line ends?
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| (...) I timed the file reading/parsing portion of the model load. It would have been more difficult to time the actual amount of time spent inside fgets/myFgets, so realistically it's likely that myFgets is even slower in comparison to fgets. The (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: Inverse matrix?
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| (...) There really is no easy way to do it. Feel free to look at TCVector::invertMatrix in the LDView code if you want to see code that does it on a 4x4 matrix. To convert a 3x3 matrix into a 4x4 matrix, put the 3x3 in the top left, put a 1 in the (...) (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: how does a line ends?
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| (...) That was quick! Thanks for taking the time to indulge me... (...) It is interesting that it was that much time difference. Are these the total load times, or just profiling of the time spent inside the fgets() routines? I see one or two things (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: how does a line ends?
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| (...) Yes, sorry that my post sounded overly defensive. I have something of a chip on my shoulder from years of working alongside programmers who want to take shortcuts at the expense of their users. Very few seem to appreciate that it is worth a (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: Inverse matrix?
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| (...) The inverse of <1,0,0,0,1,0,0,0,1,0,0,0> is itself. To compute the inverse of a general 3x3 matrix (essentially what you need to do) is rather complicated. You could do it in a macro using Gaussian elimination [1]. Tim [1] (URL) (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: how does a line ends?
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| (...) OK, as promised, here it my fgets replacement: char *myFgets(char *buf, int bufSize, FILE *file) int i; for (i = 0; i < bufSize - 1; i++) int char1 = fgetc(file); if (feof(file)) bufi = 0; if (i > 0) return buf; else return NULL; if (char1 == (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Inverse matrix?
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| Does anyone know how to generate an inverse matrix. By inverse I mean it will undo the rotation of the original matrix. I thought the inverse of <1,0,0,0,1,0,0,0,1,0,0,0> was <-1,0,0,0,-1,0,0,0,-1,0,0,0>. In other words, multiply every value by -1. (...) (20 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | | | Re: how does a line ends?
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| (...) You'll note that I didn't really say that there was anything wrong with your parsing routine (other than some personaly negative feelings about fgetc and ungetc). After fixing the bugs, it will do exactly what you say it will do. It's just (...) (20 years ago, 7-Apr-07, to lugnet.cad, FTX)
| | | | | Re: how does a line end?
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| (...) Aaah, that's one of my most common mistakes. C is the third letter, so I think of it as 13 and not 12. (...) At last, someone agrees with me. :) There will still be a theoretical risk that problems will occur, "anything that can go wrong will (...) (20 years ago, 7-Apr-07, to lugnet.cad)
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