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  • Multiple outliers for two variable linear regression

    - by Dave Jarvis
    Problem Building on my previous question, the "extreme" outliers in the following graph are somewhat obvious: Question Given: T - Set of all temperatures Y - Set of all years ST - Sum of temperatures. SY - Sum of years. N - Number of elements T(n) - Temperature of the nth element in the temperature set How would you implement an efficient MySQL stored procedure or user-defined function (UDF) to determine if T(n) is an outlier? (If such an implementation already exists, that would be good to know as well.) Related Sites I am slowly working through these sites to get a better understanding of the problem: Multiple Outliers Detection Procedures in Linear Regression M-estimator Measure of Surprise for Outlier Detection Ordinary Least Squares Linear Regression Many thanks!

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  • CSS repeat pattern with linear gradient

    - by luca
    I'm on my first approach with photoshop patterns.I'm buildin a webpage where I want to use my pattern to give a nice effect to my webpage background. The pattern I found is 120x120 px If I was done here I should use this css: background-imag:url(mypattern.jpg); background-repeat:repeat; But Im not done.Id like to *add to my page's background a linear gradient(dir=top/down col=light-blue/green) with the pattern fill layer on top of it, with blending mode=darken *. This is the final effect: I come to the point. QUESTION: Combining linear vertical-gradient effect and my 120x120 pattern is it possible to find a pattern that I could use to repeat itself endlessly both vertical and horizontal??which is a common solution in this case? Hope It's clear thanks Luca

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  • Converting linear colors to SRGB shows banding in FFmpeg

    - by user1863947
    When I convert an EXR file sequence with x264 using FFmpeg and convert the colorspace from linear to SRGB (with gamma 0.45454545) I get some heavy banding issues (most visible on a dark gradient). Here is the ffmpeg command I use: C:/ffmpeg.exe -y -i C:/seq_v001.%04d.exr -vf lutrgb=r=gammaval(0.45454545):g=gammaval(0.45454545):b=gammaval(0.45454545) -vcodec libx264 -pix_fmt yuv420p -preset slow -crf 18 -r 25 C:/out.mov Here is the output: ffmpeg version N-47062-g26c531c Copyright (c) 2000-2012 the FFmpeg developers built on Nov 25 2012 12:25:21 with gcc 4.7.2 (GCC) configuration: --enable-gpl --enable-version3 --disable-pthreads --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libnut --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libutvideo --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib libavutil 52. 9.100 / 52. 9.100 libavcodec 54. 77.100 / 54. 77.100 libavformat 54. 37.100 / 54. 37.100 libavdevice 54. 3.100 / 54. 3.100 libavfilter 3. 23.102 / 3. 23.102 libswscale 2. 1.102 / 2. 1.102 libswresample 0. 17.101 / 0. 17.101 libpostproc 52. 2.100 / 52. 2.100 Input #0, image2, from 'C:/seq_v001.%04d.exr': Duration: 00:00:09.60, start: 0.000000, bitrate: N/A Stream #0:0: Video: exr, rgb48le, 960x540 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc [libx264 @ 0000000004d11540] using SAR=1/1 [libx264 @ 0000000004d11540] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2 [libx264 @ 0000000004d11540] profile High, level 3.1 [libx264 @ 0000000004d11540] 264 - core 128 r2216 198a7ea - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=5 deblock=1:0:0 analyse=0x3:0x113 me=umh subme=8 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=18 lookahead_threads=3 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=2 b_bias=0 direct=3 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=50 rc=crf mbtree=1 crf=18.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00 Output #0, mov, to 'C:/out.mov': Metadata: encoder : Lavf54.37.100 Stream #0:0: Video: h264 (avc1 / 0x31637661), yuv420p, 960x540 [SAR 1:1 DAR 16:9], q=-1--1, 12800 tbn, 25 tbc Stream mapping: Stream #0:0 -> #0:0 (exr -> libx264) Press [q] to stop, [?] for help [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute frame= 16 fps=0.0 q=0.0 size= 0kB time=00:00:00.00 bitrate= 0.0kbits/s Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute frame= 34 fps= 33 q=0.0 size= 0kB time=00:00:00.00 bitrate= 0.0kbits/s Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute frame= 52 fps= 34 q=0.0 size= 0kB time=00:00:00.00 bitrate= 0.0kbits/s Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute frame= 68 fps= 34 q=0.0 size= 0kB time=00:00:00.00 bitrate= 0.0kbits/s Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute frame= 85 fps= 33 q=23.0 size= 47kB time=00:00:00.44 bitrate= 867.5kbits/s Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute frame= 104 fps= 34 q=23.0 size= 94kB time=00:00:01.20 bitrate= 640.3kbits/s Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute frame= 121 fps= 34 q=23.0 size= 133kB time=00:00:01.88 bitrate= 577.8kbits/s Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute frame= 139 fps= 34 q=23.0 size= 172kB time=00:00:02.60 bitrate= 543.4kbits/s Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute frame= 157 fps= 34 q=23.0 size= 213kB time=00:00:03.32 bitrate= 525.6kbits/s Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute frame= 175 fps= 34 q=23.0 size= 254kB time=00:00:04.04 bitrate= 516.0kbits/s Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute frame= 193 fps= 35 q=23.0 size= 287kB time=00:00:04.76 bitrate= 494.6kbits/s Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute frame= 211 fps= 35 q=23.0 size= 332kB time=00:00:05.48 bitrate= 496.4kbits/s Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute [exr @ 000000000dffa660] Found more than one compression attribute [exr @ 000000000dffaaa0] Found more than one compression attribute [exr @ 000000000dffaf00] Found more than one compression attribute [exr @ 000000000dffb340] Found more than one compression attribute [exr @ 000000000dffb7a0] Found more than one compression attribute [exr @ 000000000dffbbe0] Found more than one compression attribute [exr @ 000000000dffc040] Found more than one compression attribute [exr @ 000000000dff8c40] Found more than one compression attribute [exr @ 000000000dff90c0] Found more than one compression attribute [exr @ 000000000dff9520] Found more than one compression attribute [exr @ 000000000dff9960] Found more than one compression attribute [exr @ 000000000dff9dc0] Found more than one compression attribute [exr @ 000000000dffa200] Found more than one compression attribute frame= 228 fps= 34 q=23.0 size= 421kB time=00:00:06.16 bitrate= 559.8kbits/s frame= 240 fps= 32 q=-1.0 Lsize= 708kB time=00:00:09.52 bitrate= 609.3kbits/s video:705kB audio:0kB subtitle:0 global headers:0kB muxing overhead 0.505636% [libx264 @ 0000000004d11540] frame I:2 Avg QP:15.07 size: 18186 [libx264 @ 0000000004d11540] frame P:73 Avg QP:16.51 size: 3719 [libx264 @ 0000000004d11540] frame B:165 Avg QP:18.38 size: 2502 [libx264 @ 0000000004d11540] consecutive B-frames: 2.5% 3.3% 42.5% 51.7% [libx264 @ 0000000004d11540] mb I I16..4: 46.2% 33.3% 20.4% [libx264 @ 0000000004d11540] mb P I16..4: 6.8% 2.0% 0.6% P16..4: 29.4% 10.5% 4.6% 0.0% 0.0% skip:46.1% [libx264 @ 0000000004d11540] mb B I16..4: 1.8% 0.7% 0.2% B16..8: 40.9% 6.5% 0.3% direct: 1.2% skip:48.5% L0:52.0% L1:47.5% BI: 0.5% [libx264 @ 0000000004d11540] 8x8 transform intra:24.7% inter:81.3% [libx264 @ 0000000004d11540] direct mvs spatial:93.3% temporal:6.7% [libx264 @ 0000000004d11540] coded y,uvDC,uvAC intra: 10.7% 31.4% 24.9% inter: 2.3% 9.0% 2.9% [libx264 @ 0000000004d11540] i16 v,h,dc,p: 83% 11% 6% 1% [libx264 @ 0000000004d11540] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 9% 9% 52% 6% 4% 4% 5% 5% 5% [libx264 @ 0000000004d11540] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 22% 11% 44% 5% 4% 3% 3% 4% 3% [libx264 @ 0000000004d11540] i8c dc,h,v,p: 69% 15% 15% 2% [libx264 @ 0000000004d11540] Weighted P-Frames: Y:0.0% UV:0.0% [libx264 @ 0000000004d11540] ref P L0: 48.9% 0.1% 16.8% 17.0% 11.3% 5.8% [libx264 @ 0000000004d11540] ref B L0: 57.7% 21.9% 13.9% 6.4% [libx264 @ 0000000004d11540] ref B L1: 82.4% 17.6% [libx264 @ 0000000004d11540] kb/s:600.61 For me it looks like it converts the video first and afterwards applies the gamma correction on 8-bit clipped video. Does someone have an idea?

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  • Points on lines where the two lines are the closest together

    - by James Bedford
    Hey guys, I'm trying to find the points on two lines where the two lines are the closest. I've implemented the following method (Points and Vectors are as you'd expect, and a Line consists of a Point on the line and a non-normalized direction Vector from that point): void CDClosestPointsOnTwoLines(Line line1, Line line2, Point* closestPoints) { closestPoints[0] = line1.pointOnLine; closestPoints[1] = line2.pointOnLine; Vector d1 = line1.direction; Vector d2 = line2.direction; float a = d1.dot(d1); float b = d1.dot(d2); float e = d2.dot(d2); float d = a*e - b*b; if (d != 0) // If the two lines are not parallel. { Vector r = Vector(line1.pointOnLine) - Vector(line2.pointOnLine); float c = d1.dot(r); float f = d2.dot(r); float s = (b*f - c*e) / d; float t = (a*f - b*c) / d; closestPoints[0] = line1.positionOnLine(s); closestPoints[1] = line2.positionOnLine(t); } else { printf("Lines were parallel.\n"); } } I'm using OpenGL to draw three lines that move around the world, the third of which should be the line that most closely connects the other two lines, the two end points of which are calculated using this function. The problem is that the first point of closestPoints after this function is called will lie on line1, but the second point won't lie on line2, let alone at the closest point on line2! I've checked over the function many times but I can't see where the mistake in my implementation is. I've checked my dot product function, scalar multiplication, subtraction, positionOnLine() etc. etc. So my assumption is that the problem is within this method implementation. If it helps to find the answer, this is function supposed to be an implementation of section 5.1.8 from 'Real-Time Collision Detection' by Christer Ericson. Many thanks for any help!

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  • How to detect 2D line on line collision?

    - by Vish
    I'm a flash actionscript game developer who is a bit backward with mathematics, though I find physics both interesting and cool. For reference this is a similar game to the one I'm making: Untangled flash game I have made an untangled game almost to full completion of logic. But, when two lines intersect, I need those intersected or 'tangled' lines to show a different color; red. It would be really kind of you people if you could suggest an algorithm with/without math for detecting line segment collisions. I'm basically a person who likes to think 'visually' than 'arithmetically' :) P.S I'm trying to make a function as private function isIntersecting(A:Point, B:Point, C:Point, D:Point):Boolean Thanks in advance.

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  • Detect line line collision in an Untangled game

    - by Vish
    Pardon me if this is a repeat question,but I've been searching google for vain since the past few days, I'm a flash actionscript game developer who is a bit backward with mathematics, though I find physics both interesting and cool. Similiar game : Untangled flash game I have made an untangled game almost to full completion of logic. But, when two lines intersect , I need those intersected or 'tangled' lines to show a different color; red. It would be really kind of you people if you could suggest an algorithm with / without math for detecting line segment collisions. I'm basically a person who likes to think 'visually' than 'arithmetically' :) P.S I'm trying to make a function as private function isIntersecting(A:Point, B:Point, C:Point, D:Point):Boolean Thanks in advance. Vishnu Ajit

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  • View matrix in opengl

    - by user5584
    Hi! Sorry for my clumsy question. But I don't know where I am wrong at creating view matrix. I have the following code: createMatrix(vec4f(xAxis.x, xAxis.y, xAxis.z, dot(xAxis,eye)), vec4f( yAxis.x_, yAxis.y_, yAxis.z_, dot(yAxis,eye)), vec4f(-zAxis.x_, -zAxis.y_, -zAxis.z_, -dot(zAxis,eye)), vec4f(0, 0, 0, 1)); //column1, column2,... I have tried to transpose it, but with no success. I have also tried to use gluLookAt(...) with success. At the reference page, I watched the remarks about the to-be-created matrix, and it seems the same as mine. Where I am wrong?

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  • Transform between two 3d cartesian coordinate systems

    - by Pris
    I'd like to know how to get the rotation matrix for the transformation from one cartesian coordinate system (X,Y,Z) to another one (X',Y',Z'). Both systems are defined with three orthogonal vectors as one would expect. No scaling or translation occurs. I'm using OpenSceneGraph and it offers a Matrix convenience class, if it makes finding the matrix easier: http://www.openscenegraph.org/documentation/OpenSceneGraphReferenceDocs/a00403.html.

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  • How to implement a simple bullet trajectory

    - by AirieFenix
    I searched and searched and although it's a fair simple question, I don't find the proper answer but general ideas (which I already have). I have a top-down game and I want to implement a gun which shoots bullets that follow a simple path (no physics nor change of trajectory, just go from A to B thing). a: vector of the position of the gun/player. b: vector of the mouse position (cross-hair). w: the vector of the bullet's trajectory. So, w=b-a. And the position of the bullet = [x=x0+speed*time*normalized w.x , y=y0+speed*time * normalized w.y]. I have the constructor: public Shot(int shipX, int shipY, int mouseX, int mouseY) { //I get mouse with Gdx.input.getX()/getY() ... this.shotTime = TimeUtils.millis(); this.posX = shipX; this.posY = shipY; //I used aVector = aVector.nor() here before but for some reason didn't work float tmp = (float) (Math.pow(mouseX-shipX, 2) + Math.pow(mouseY-shipY, 2)); tmp = (float) Math.sqrt(Math.abs(tmp)); this.vecX = (mouseX-shipX)/tmp; this.vecY = (mouseY-shipY)/tmp; } And here I update the position and draw the shot: public void drawShot(SpriteBatch batch) { this.lifeTime = TimeUtils.millis() - this.shotTime; //position = positionBefore + v*t this.posX = this.posX + this.vecX*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); this.posY = this.posY + this.vecY*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); ... } Now, the behavior of the bullet seems very awkward, not going exactly where my mouse is (it's like the mouse is 30px off) and with a random speed. I know I probably need to open the old algebra book from college but I'd like somebody says if I'm in the right direction (or points me to it); if it's a calculation problem, a code problem or both. Also, is it possible that Gdx.input.getX() gives me non-precise position? Because when I draw the cross-hair it also draws off the cursor position. Sorry for the long post and sorry if it's a very basic question. Thanks!

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  • How can I calculate a vertex normal for a hard edge?

    - by K.G.
    Here is a picture of a lovely polygon: Circled is a vertex, and numbered are its adjacent faces. I have calculated the normals of those faces as such (not yet normalized, 0-indexed): Vertex 1 normal 0: 0.000000 0.000000 -0.250000 Vertex 1 normal 1: 0.000000 0.000000 -0.250000 Vertex 1 normal 2: -0.250000 0.000000 0.000000 Vertex 1 normal 3: -0.250000 0.000000 0.000000 Vertex 1 normal 4: 0.250000 0.000000 0.000000 What I'm wondering is, how can I determine, taken as given that I want this vertex to represent a hard edge, whether its normal should be the normal of 1/2 or 3/4? My plan after I glanced at the sketch I used to put this together was "Ha! I'll just use whichever two faces have the same normal!" and now I see that there are two sets of two faces for which this is true. Is there a rule I can apply based on the face winding, angle of the adjacent edges, moon phase, coin flip, to consistently choose a normal direction for this box? For the record, all of the other polygons I plan to use will have their normals dictated in Maya, but after encountering this problem, it made me really curious.

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  • Make an object slide around an obstacle

    - by Isaiah
    I have path areas set up in a game I'm making for canvas/html5 and have got it working to keep the player within these areas. I have a function isOut(boundary, x, y) that returns true if the point is outside the boundary. What I do is check only the new position x/y separately with the corresponding old position x/y. Then if each one is out I assign them the past value from the frame before. The old positions are kept in a variable from a closure I made. like this: opos = [x,y];//old position npos = [x,y];//new position if(isOut(bound, npos[0], opos[1])){ npos[0] = opos[0]; //assign it the old x position } if(isOut(bound, opos[0], npos[1])){ npos[1] = opos[1]; //assign it the old y position } It looks nice and works good at certain angles, but if your boundary has diagonal regions it results in jittery motion. What's happening is the y pos exits the area while x doesn't and continues pushing the player to the side, once it has moved the player to the side a bit the player can move forward and then the y exits again and the whole process repeats. Anyone know how I may be able to achieve a smoother slide? I have access to the player's velocity vector, the angle, and the speed(when used with the angle). I can move the play with either angle/speed or x/yvelocities as I've built in backups to translate one to the other if either have been altered manually.

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  • How can I test if a point lies between two parallel lines?

    - by Harold
    In the game I'm designing there is a blast that shoots out from an origin point towards the direction of the mouse. The width of this blast is always going to be the same. Along the bottom of the screen (what's currently) squares move about which should be effected by the blast that the player controls. Currently I am trying to work out a way to discover if the corners of these squares are within the blast's two bounding lines. I thought the best way to do this would be to rotate the corners of the square around an origin point as if the blast were completely horizontal and see if the Y values of the corners were less than or equal to the width of the blast which would mean that they lie within the effected region, but I can't work out

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  • Moving objects colliding when using unalligned collision avoidance (steering)

    - by James Bedford
    I'm having trouble with unaligned collision avoidance for what I think is a rare case. I have set two objects to move towards each other but with a slight offset, so one of the objects is moving slightly upwards, and one of the objects is moving slightly downwards. In my unaligned collision avoidance steering algorithm I'm finding the points on the object's forward line and the other object's forward line where these two lines are the closest. If these closest points are within a collision avoidance distance, and if the distance between them is smaller than the two radii of the two object's bounding spheres, then the objects should steer away in the appropriate direction. The problem is that for my case, the closest points on the lines are calculated to be really far away from the actual collision point. This is because the two forward lines for each object are moving away from each other as the objects pass. The problem is that because of this, no steering takes place, and the two objects partially collide. Does anyone have any suggestions as to how I can correctly calculate the point of collision? Perhaps by somehow taking into account the size of the two objects?

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  • Best way to implement a simple bullet trajectory

    - by AirieFenix
    I searched and searched and although it's a fair simple question, I don't find the proper answer but general ideas (which I already have). I have a top-down game and I want to implement a gun which shoots bullets that follow a simple path (no physics nor change of trajectory, just go from A to B thing). a: vector of the position of the gun/player. b: vector of the mouse position (cross-hair). w: the vector of the bullet's trajectory. So, w=b-a. And the position of the bullet = [x=x0+speed*time*normalized w.x , y=y0+speed*time * normalized w.y]. I have the constructor: public Shot(int shipX, int shipY, int mouseX, int mouseY) { //I get mouse with Gdx.input.getX()/getY() ... this.shotTime = TimeUtils.millis(); this.posX = shipX; this.posY = shipY; //I used aVector = aVector.nor() here before but for some reason didn't work float tmp = (float) (Math.pow(mouseX-shipX, 2) + Math.pow(mouseY-shipY, 2)); tmp = (float) Math.sqrt(Math.abs(tmp)); this.vecX = (mouseX-shipX)/tmp; this.vecY = (mouseY-shipY)/tmp; } And here I update the position and draw the shot: public void drawShot(SpriteBatch batch) { this.lifeTime = TimeUtils.millis() - this.shotTime; //position = positionBefore + v*t this.posX = this.posX + this.vecX*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); this.posY = this.posY + this.vecY*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); ... } Now, the behavior of the bullet seems very awkward, not going exactly where my mouse is (it's like the mouse is 30px off) and with a random speed. I know I probably need to open the old algebra book from college but I'd like somebody says if I'm in the right direction (or points me to it); if it's a calculation problem, a code problem or both. Also, is it possible that Gdx.input.getX() gives me non-precise position? Because when I draw the cross-hair it also draws off the cursor position. Sorry for the long post and sorry if it's a very basic question. Thanks!

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  • Understanding dot notation

    - by Starkers
    Here's my interpretation of dot notation: a = [2,6] b = [1,4] c = [0,8] a . b . c = (2*6)+(1*4)+(0*8) = 12 + 4 + 0 = 16 What is the significance of 16? Apparently it's a scalar. Am I right in thinking that a scalar is the number we times a unit vector by to get a vector that has a scaled up magnitude but the same direction as the unit vector? So again, what is the relevance of 16? When is it used? It's not the magnitude of all the vectors added up. The magnitude of all of them is calculated as follows: sqrt( ax * ax + ay * ay ) + sqrt( bx * bx + by * by ) + sqrt( cx * cx + cy * cy) sqrt( 2 * 2 + 6 * 6 ) + sqrt( 1 * 1 + 4 * 4 ) + sqrt( 0 * 0 + 8 * 8) sqrt( 4 + 36 ) + sqrt( 1 + 16 ) + sqrt( 0 + 64) sqrt( 40 ) + sqrt( 17 ) + sqrt( 64) 6.3 + 4.1 + 8 10.4 + 8 18.4 So I don't really get this diagram: Attempting with sensible numbers: a = [1,0] b = [4,3] a . b = (1*0) + (4*3) = 0 + 12 = 12 So what exactly is a . b describing here? The magnitude of that vector? Because that isn't right: the 'a.b' vector = [4,0] sqrt( x*x + y*y ) sqrt( 4*4 + 0*0 ) sqrt( 16 + 0 ) 4 So what is 12 describing?

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  • Lerping to a center point while in motion

    - by Fibericon
    I have an enemy that initially flies in a circular motion, while facing away from the center point. This is how I achieve that: position.Y = (float)(Math.Cos(timeAlive * MathHelper.PiOver4) * radius + origin.Y); position.X = (float)(Math.Sin(timeAlive * MathHelper.PiOver4) * radius + origin.X); if (timeAlive < 5) { angle = (float)Math.Atan((0 - position.X) / (0 - position.Y)); if (0 < position.Y) RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(-1 * angle); else RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(MathHelper.Pi - angle); } That part works just fine. After five seconds of this, I want the enemy to turn inward, facing the center point. However, I've been trying to lerp to that point, since I don't want it to simply jump to the new rotation. Here's my code for trying to do that: else { float newAngle = -1 * (float)Math.Atan((0 - position.X) / (0 - position.Y)); angle = MathHelper.Lerp(angle, newAngle, (float)gameTime.ElapsedGameTime.Milliseconds / 1000); if (0 < position.Y) RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(MathHelper.Pi - angle); else RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(-1 * angle); } That doesn't work so fine. It seems like it's going to at first, but then it just sort of skips around. How can I achieve what I want here?

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  • How to get xy coordinates along a given path

    - by netbrain
    Say i have two points (x,y), (0,0) and (10,10). Now i wan´t to get coordinates along the line by stepping through values of x and y. I thought i solved it with the following functions: fy = startY + (x - startX) * ((destY-startY)/(destX-startX)); fx = (y + startY) / ((destY-startY)/(destX-startX)) + startX; taken from http://en.wikipedia.org/wiki/Linear_interpolation However, it seems that im getting a problem when destX and startX is the same value, so you get division by zero. Is there a better way of getting coordinates along a line when knowing the start and endpoint of the line?

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  • Trouble with Collada bones

    - by KyleT
    I have a Collada file with a rigged mesh. I've read the node tags in the library_visual_scenes tag and extracted the matrix for each node and stored everything in a hierarchical bone structure. My Matrix container is "row major", so I'd store the first float of a matrix tag in the 1st row, 1st column, the second in the 1st row, 2nd column, etc. From what I gather this is the Bind Pose Matrix. After that I went through the tag and extracted the float array in the source tag of the skin tag of the controller for the mesh. I stored each matrix from this float array in their corresponding Bone as the Inverse Bind Matrix. I also extracted the bind-shape-matrix and stored it. Now I'd like to draw the skeleton with OpenGL to see if everything is working correctly before I go about skinning. I iterate once over my bones and multiply a bone's Bind Pose Matrix by it's parents and store that. After that I iterate again over the bones and multiply the result of the previous matrix multiplication by the Inverse Bind Matrix and then by the Bind Shape Matrix. The results look something like this: [0.2, 9.2, 5.8, 1.2 ] [4.6, -3.3, -0.2, -0.1 ] [-1.8, 0.2, -4.2, -3.9 ] [0, 0, 0, 1 ] I've had to go to various sources to get the little understanding of Collada I have and books about 3d transform matricies can get pretty intense. I've hit a brick wall and if you could please read through this and see if there is something I'm doing wrong, and how I'd go about getting an X,Y,Z to draw a point for each of these joints once I've calculated the final transform, I'd really appreciate it.

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  • Matrices: Arrays or separate member variables?

    - by bjz
    I'm teaching myself 3D maths and in the process building my own rudimentary engine (of sorts). I was wondering what would be the best way to structure my matrix class. There are a few options: Separate member variables: struct Mat4 { float m11, m12, m13, m14, m21, m22, m23, m24, m31, m32, m33, m34, m41, m42, m43, m44; // methods } A multi-dimensional array: struct Mat4 { float[4][4] m; // methods } An array of vectors struct Mat4 { Vec4[4] m; // methods } I'm guessing there would be positives and negatives to each. From 3D Math Primer for Graphics and Game Development, 2nd Edition p.155: Matrices use 1-based indices, so the first row and column are numbered 1. For example, a12 (read “a one two,” not “a twelve”) is the element in the first row, second column. Notice that this is different from programming languages such as C++ and Java, which use 0-based array indices. A matrix does not have a column 0 or row 0. This difference in indexing can cause some confusion if matrices are stored using an actual array data type. For this reason, it’s common for classes that store small, fixed size matrices of the type used for geometric purposes to give each element its own named member variable, such as float a11, instead of using the language’s native array support with something like float elem[3][3]. So that's one vote for method one. Is this really the accepted way to do things? It seems rather unwieldy if the only benefit would be sticking with the conventional math notation.

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  • Portal View/Projection Matrix near plane

    - by melak47
    For RenderToTexture/Camera based portal rendering, the basics seems simple enough. However, with a free camera, most of the time it is going to be looking at such portals at an angle: Now a regular near clipping plane will not always work here, it will either intersect with the wall the portal is sitting on, or possibly with objects in front of the wall. The desired near clipping plane would be aligned like the portal, producing a view volume more like this: or this in 3D: So here is my question: How does one construct or "truncate" a view/projection matrix to achieve such an off-camera-normal (near) clipping plane?

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  • Mouse pointer position to screen space

    - by Ylisar
    If I have a mouse pointer position in pixels of canvas, I can easily convert it to the -1..1 range for both X & Y by lerping by dividing with canvas dimensions. However, the problem is what I should put in Z & W if I want my screen space position to be on the near plane? The step afterwards would be for me to multiply by the inverse of view-projection to take me to world space, where I easily can construct a ray from the cameras world space position.

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  • Use a vector to index a matrix without linear index

    - by David_G
    G'day, I'm trying to find a way to use a vector of [x,y] points to index from a large matrix in MATLAB. Usually, I would convert the subscript points to the linear index of the matrix.(for eg. Use a vector as an index to a matrix in MATLab) However, the matrix is 4-dimensional, and I want to take all of the elements of the 3rd and 4th dimensions that have the same 1st and 2nd dimension. Let me hopefully demonstrate with an example: Matrix = nan(4,4,2,2); % where the dimensions are (x,y,depth,time) Matrix(1,2,:,:) = 999; % note that this value could change in depth (3rd dim) and time (4th time) Matrix(3,4,:,:) = 888; % note that this value could change in depth (3rd dim) and time (4th time) Matrix(4,4,:,:) = 124; Now, I want to be able to index with the subscripts (1,2) and (3,4), etc and return not only the 999 and 888 which exist in Matrix(:,:,1,1) but the contents which exist at Matrix(:,:,1,2),Matrix(:,:,2,1) and Matrix(:,:,2,2), and so on (IRL, the dimensions of Matrix might be more like size(Matrix) = (300 250 30 200) I don't want to use linear indices because I would like the results to be in a similar vector fashion. For example, I would like a result which is something like: ans(time=1) 999 888 124 999 888 124 ans(time=2) etc etc etc etc etc etc I'd also like to add that due to the size of the matrix I'm dealing with, speed is an issue here - thus why I'd like to use subscript indices to index to the data. I should also mention that (unlike this question: Accessing values using subscripts without using sub2ind) since I want all the information stored in the extra dimensions, 3 and 4, of the i and jth indices, I don't think that a slightly faster version of sub2ind still would not cut it..

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  • How to partition bits in a bit array with less than linear time

    - by SiLent SoNG
    This is an interview question I faced recently. Given an array of 1 and 0, find a way to partition the bits in place so that 0's are grouped together, and 1's are grouped together. It does not matter whether 1's are ahead of 0's or 0's are ahead of 1's. An example input is 101010101, and output is either 111110000 or 000011111. Solve the problem in less than linear time. Make the problem simpler. The input is an integer array, with each element either 1 or 0. Output is the same integer array with integers partitioned well. To me, this is an easy question if it can be solved in O(N). My approach is to use two pointers, starting from both ends of the array. Increases and decreases each pointer; if it does not point to the correct integer, swap the two. int * start = array; int * end = array + length - 1; while (start < end) { // Assume 0 always at the end if (*end == 0) { --end; continue; } // Assume 1 always at the beginning if (*start == 1) { ++start; continue; } swap(*start, *end); } However, the interview insists there is a sub-linear solution. This makes me thinking hard but still not get an answer. Can anyone help on this interview question?

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