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  • How do I build a matrix to translate one set of points to another?

    - by dotminic
    I've got 3 points in space that define a triangle. I've also got a vertex buffer made up of three vertices, that also represent a triangle that I will refer to as a "model". How can I can I find the matrix M that will transform vertex in my buffer to those 3 points in space ? For example, let's say my three points A, B, C are at locations: A.x = 10, A.y = 16, A.z = 8 B.x = 12, B.y = 11, B.z = 1 C.x = 19, C.y = 12, C.z = 3 given these coordinates how can I build a matrix that will translate and rotate my model such that both triangles have the exact same world space ? That is, I want the first vertex in my triangle model to have the same coordinates as A, the second to have the same coordinates as B, and same goes for C. nb: I'm using instanced rendering so I can't just give each vertex the same position as my 3 points. I have a set of three points defining a triangle, and only three vertices in my vertex buffer.

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  • Algorithm to zoom a plotted function

    - by astinx
    I'm making a game in android and I need plot a function, my algorithm is this: @Override protected void onDraw(Canvas canvas) { float e = 0.5f; //from -x axis to +x evaluate f(x) for (float x = -z(canvas.getWidth()); x < z(canvas.getWidth()); x+=e) { float x1,y1; x1 = x; y1 = f(x); canvas.drawPoint((canvas.getWidth()/2)+x1, (canvas.getHeight()/2)-y1, paintWhite); } super.onDraw(canvas); } This is how it works. If my function is, for example f(x)=x^2, then z(x) is sqrt(x). I evaluate each point between -z(x) to z(x) and then I draw them. As you can see I use the half of the size of the screen to put the function in the middle of the screen. The problem isn't that the code isn't working, actually plots the function. But if the screen is of 320*480 then this function will be really tiny like in the image below. My question is: how can I change this algorithm to scale the function?. BTW what I'm really wanting to do is trace a route to later display an animated sprite, so actually scale this image doesnt gonna help me. I need change the algorithm in order to draw the same interval but in a larger space. Any tip helps, thanks! Current working result Desired result UPDATE: I will try explain more in detail what the problem is. Given this interval [-15...15] (-z(x) to z(x)) I need divide this points in a bigger interval [-320...320] (-x to x). For example, when you use some plotting software like this one. Although the div where is contain the function has 640 px of width, you dont see that the interval is from -320 to 320, you see that the interval is from -6 to 6. How can I achieve this?

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  • How do you blend multiple colors in HSV (polar) color-space?

    - by Toxikman
    In RGB color space, you can do a weighted multiple-color blend by just doing: Start with R = G = B = 0. Then we perform a blend at index i using a set of colors C, and a set of normalized weights w like so: R += w[i] * C[i].r G += w[i] * C[i].g B += w[i] * C[i].b But I'd like to interpolate the colors in the HSV color-space instead, so that saturation and brightness are uniform across the interpolation. I know I can blend saturation and brightness in the same way as above, but the HUE component is an angle around a continuous circle, since HSV is essentially a polar coordinate system. Blending only two HSV colors makes sense to me, you just find the shortest arc around the circle and interpolate between the two hues. But when you attempt to blend more than 2 colors, it becomes a bit of a puzzle. You have to handle anomalous cases, like 4 equally-weighted colors with a hue at 0, 90, 180, and 270 degrees. They basically cancel each other out, so any hue will do. Any ideas would be greatly appreciated.

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  • Modular spaceship control

    - by SSS
    I am developing a physics based game with spaceships. A spaceship is constructed from circles connected by joints. Some of the circles have engines attached. Engines can rotate around the center of circle and create thrust. I want to be able to move the ship in a direction or rotate around a point by setting the rotation and thrust for each of the ship's engines. How can I find the rotation and thrust needed for each engine to achieve this?

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  • Moving two objects proportionally

    - by SSL
    I'm trying to move two objects away from each other at a proportional distance, but on different scales. I'm not quite sure how to do this. Object A can go from position 0.1 to 1. Object B has no limits. If object B is decreasing, then Object A should be decreasing at rate R. Likewise, if Object B is increasing, then Object A increases at rate R. How can I tie these two Object positions together so that in an update loop, they automatically update their positions? I tried using: ObjA.Pos += 0.001f * ObjB.VelocityY; //0.001f is the rate This works but there's an error each time it runs. ObjA starts off at its max position 1 but then the next time it will stop at 0.97, 0.94, 0.91 etc.. This is due to the 0.001f rate I put in. Is there a way to control the rate, yet not end up with the rounding error?

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  • setting the position in different resolution

    - by Moaz
    I have a normal game window which is 640*480, and everything is fine, but when I try to maximize the window, the objects translate to different positions on the screen, for example If I have a circle which is drawn at the center in the normal window, when I try to maximize it, it shifts away from the center of the screen. How do I adjust it so it draws at the center in both normal window and maximized window ?

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  • How to determine which thrusters to turn on to rotate the ship?

    - by migimunz
    The configuration of the ship changes dynamically, so I have to determine which thruster to turn on when I want to rotate the ship clockwise or counter clockwise. The thrusters are always axis aligned with the ship (never at an angle) and are either on or off. Here's one of the possible setups: What I've tried so far is to visualize the firing vector and the direction vector to the center of mass of the ship: Unfortunately, I didn't get very far with that.

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  • Get all triangles that are < N dist from you?

    - by CyanPrime
    Does anyone know of a way I could add a radius to this code for p? Like basically saying "this is true if the triangle is < N dist from the point" public boolean isPointInTriangle( Vector3f p, Vector3f a, Vector3f b, Vector3f c ) { return ( pointsAreOnSameSide(p, a, b, c) && pointsAreOnSameSide(p, b, a, c) && pointsAreOnSameSide(p, c, a, b) ); } public boolean pointsAreOnSameSide( Vector3f p1, Vector3f p2, Vector3f a, Vector3f b ) { Vector3f diffba = new Vector3f(0,0,0); Vector3f.sub( b, a, diffba ); Vector3f diffp1a = new Vector3f(0,0,0); Vector3f.sub( p1, a, diffp1a ); Vector3f diffp2a = new Vector3f(0,0,0); Vector3f.sub( p2, a, diffp2a ); Vector3f cross1 = Vector3f.cross(diffba, diffp1a); Vector3f cross2 = Vector3f.cross(diffba, diffp2a); return ( Vector3f.dot( cross1, cross2 ) >= 0 ); }

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  • Should Equality be commutative within a Class Hierachy?

    - by vossad01
    It is easy to define the Equals operation in ways that are not commutative. When providing equality against other types, there are obviously situations (in most languages) were equality not being commutative is unavoidable. However, within one's own inheritance hierarchy where the root base class defines an equality member, a programmer has more control. Thus you can create situations where (A = B) ? (B = A), where A and B both derive from base class T Substituting the = with the appropriate variation for a given language. (.Equals(_), ==, etc.) That seems wrong to me, however, I recognize I may be biased by background in Mathematics. I have not been in programming long enough to know what is standard/accepted/preferred practice when programming. Do most programmers just accept .Equals(_)may not be commutative and code defensibly. Do they expect commutativity and get annoyed if it is not. In short, when working in a class hierarchy, should effort me made to ensure Equality is commutative?

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  • Fastest way to check if two square 2D arrays are rotationally and reflectively distinct

    - by kustrle
    The best idea I have so far is to rotate first array by {0, 90, 180, 270} degrees and reflect it horizontally or/and vertically. We basically get 16 variations [1] of first array and compare them with second array. if none of them matches the two arrays are rotationally and reflectively distinct. I am wondering if there is more optimal solution than this brute-force approach? [1] 0deg, no reflection 0deg, reflect over x 0deg, reflect over y 0deg, reflect over x and y 90deg, no reflection ...

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  • Orienting ship movement in asteroids [closed]

    - by BadSniper
    Possible Duplicate: Move sprite in the direction it is facing? I'm programming asteroids game. I'm trying to give velocity in the direction of ship face. I've tried using velocity.x = velocity.x * cos r, velocity.y = velocity.y * sin r where velocity is a vector and r is the angle rotated. but it's not moving in right direction. Could someone help with this problem? It is supposed to return the vector in which ship is facing. I don't understand the problem.

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  • Simulating a sine wave/oscillating pattern for enemies

    - by Sun
    I'm creating a simple top down shooter, right now I have an enemy which simply follows the player. I'd like to change things up and have the enemies move towards the player but in a wave like motion. I have looked at some similar questions like this but they don't take into account for the Y changing. How can I simulate a wave like pattern for my enemies whilst they are homing into their target. Edit: Sample code In my update method I have the following: Vector2 trackingPos = position - target; trackingPos.Normalize(); position -= trackingPos * elaspedTime * speed;

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  • How to calculate shot angle and velocity to hit a moving target?

    - by Guen
    I am developing a 2D Android game and I am making an aiming algorithm for AI projectiles to hit enemies either following a path, or free moving. At the moment it just calculates where the target will be after a distance and fires a projectile to meet it at that distance. Of course this means varying the projectile speed to meet the target. Does anyone have any tips for a simple-ish algorithm (optimal-ish) to calculate when the projectile needs to fire and where it needs to aim if it can only travel at a constant velocity? Say the projectile goes twice the speed of the target? The only way I can think of involves searching and seems quite large.

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  • Vector transform equation explanation

    - by cyberdemon
    I'm trying to understand the maths of moving points in a 3d space by making a game written in C#. I'm looking at this wolfire blog series which explains some basic 3d maths. I've read the first two parts but am stuck on the 3rd. I know it's all really rudimentary stuff but I find Googling for help with equations really hard. The one I'm struggling with is: 0*(0.66,0.75) + 2*(-0.75, 0.66) = (-1.5, 1.3) How can anything multiplied by 0 not be 0? So my question is how does this look in code: x(a,b) + y(c,d) I know it's basic stuff but I just can't see it.

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  • Camera not working

    - by user17548
    I made a camera in DX9. To move forward I press the Up arrow. To rotate on the Y axis I use the mouse. When I perform these movements on their own the camera moves at the speed I want. However, if I hold down Up and move the mouse at the same time then the camera moves a lot faster than it should. I want it to move at the same speed as it does when only the Up arrow is pressed. I think I need to normalize something somewhere but not sure what and not sure where. Have tried various combinations without success so if anyone can point me in the right direction that would be great. Thanks. My code #define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0) LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam ) { if( KEY_DOWN(VK_UP)) MovePlayer(D3DXVECTOR3(0, 0, -1.0f)); if( KEY_DOWN(VK_DOWN)) MovePlayer(D3DXVECTOR3(0, 0, 1.0f)); switch( msg ) { case WM_MOUSEMOVE: ProcessMouseInput(); } } void MovePlayer( D3DXVECTOR3 in_vec ) { D3DXMATRIX CameraRot; D3DXMatrixRotationY(&CameraRot,D3DXToRadian(AngleY)); D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&in_vec,&CameraRot); CameraPos += (m_timeElapsed * CameraRotTarget); } void ProcessMouseInput() { GetCursorPos( &CurrentMouseState ); if ((CurrentMouseState.x != GameMouseState.x) || (CurrentMouseState.y != GameMouseState.y)) { int dx = CurrentMouseState.x - GameMouseState.x; int dy = CurrentMouseState.y - GameMouseState.y; AngleY+=m_timeElapsed*dx*7.0f; } GameMouseState = CurrentMouseState; // Set back to window center in Render function } VOID UpdateCamera() { D3DXVECTOR3 CameraOrigTarget(0, 0, -1); D3DXVECTOR3 CameraOrigUp(0, 1, 0); D3DXMATRIX CameraRot; D3DXMATRIX CameraRotX; D3DXMatrixRotationX(&CameraRotX,D3DXToRadian(AngleX)); D3DXMATRIX CameraRotY; D3DXMatrixRotationY(&CameraRotY,D3DXToRadian(AngleY)); CameraRot = CameraRotX * CameraRotY; D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&CameraOrigTarget,&CameraRot); D3DXVECTOR3 CameraTarget; CameraTarget = CameraPos + CameraRotTarget; D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f ); D3DXMatrixLookAtLH( &matView, &CameraPos, &CameraTarget, &vUpVec ); g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView ); D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI / 4, 1.0f, 1.0f, 100.0f ); g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj ); }

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  • How can I find the closest vector to another in a specific direction?

    - by Sniper
    Perhaps I am not phrasing it incorrectly in my searches, but I can not find anything on this. I have a vector3 with a specific direction that it is facing, I want to get the closest object to that position in that specific direction. Basically I want to get the object that is being aimed at. I have thought about finding all objects within a box and then finding the closest object to my vector from them results, but I am sure that there is a more efficient way. The Z axis is optional, the objects are most likely within a few meters of the search vector. http://i.stack.imgur.com/FafAu.jpg

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  • Why use other bases when programming [closed]

    - by JMD
    Possible Duplicate: Why use other number bases when programming My coworkers and I have been bending our minds to figuring out why anyone would go out of their way to program numbers in a base other than base 10. I suggested that perhaps you could optimize longer equations by putting the variables in the correct base you are working with (for instance, if you have only sets of 5 of something with no remainders you could use base 5), but I'm not sure if that's true. Any thoughts?

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  • Characteristics, what's the inverse of (x*(x+1))/2? [closed]

    - by Valmond
    In my game you can spend points to upgrade characteristics. Each characteristic has a formula like: A) out = in : for one point spent, one pont gained (you spend 1 point on Force so your force goes from 5 to 6) B) out = last level (starting at 1) : so the first point spent earns you 1 point, the next point spent earns you an additional 2 and so on (+3,+4,+5...) C) The inverse of B) : You need to spend 1 point to earn one, then you need to spend 2 to earn another one and so on. I have already found the formula for calculating the actual level of B when points spent = x : charac = (x*(x+1))/2 But I'd like to know what the "reverse" version of B) (usable for C) is, ie. if I have spent x points, how many have I earned if 1 spent gives 1, 1+2=3 gives 2, 1+2+3=6 gives 3 and so on. I know I can just calculate the numbers but I'd like to have the formula because its neater and so that I can stick it in an excel sheet for example... Thanks! ps. I think I have nailed it down to something like charac = sqrt( x*m +k) but then I'm stuck doing number guessing for k and m and I feel I might be wrong anyway as I get close but never hits the spot.

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  • shorten something in AS 2.0 using eval or set?

    - by chris
    eval("_parent.volumetone" + target1)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target2)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target3)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target4)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target5)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target6)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target7)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target8)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target9)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target10)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target11)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target12)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target13)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target14)._yscale = Math.round(number)/1.5+50; eval("_parent.volumetone" + target15)._yscale = Math.round(number)/1.5+50; i have these lines of repetitive code. the variables target1 to target15 are a random number between 1 and 110. so one may point to _parent.volumetone49 and adjust its _yscale for example. the code above works the way i want, but i want it shorter. here's something i tried with no success: for (i = 0; i < 15; i++) { set("_parent.volumetone" + ("target"+i) + "._xscale", Math.round(funhousenumber)/1.5+50); } basically having a loop that starts at 1 and goes to 15, then replaces target1 with target+i, i being 1, which would give target1 and thus the number contained in it. maybe i have to use eval()? i'm still not sure what i'm doing but i'm learning as i go. thanks.

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  • program won't find math.h anymore

    - by 130490868091234
    After a long time, I downloaded a program I co-developed and tried to recompile it on my Ubuntu Linux 12.04, but it seems it does not find math.h anymore. This may be because something has changed recently in gcc, but I can't figure out if it's something wrong in src/Makefile.am or a missing dependency: Download from http://www.ub.edu/softevol/variscan/: tar xzf variscan-2.0.2.tar.gz cd variscan-2.0.2/ make distclean sh ./autogen.sh make I get: [...] gcc -DNDEBUG -O3 -W -Wall -ansi -pedantic -lm -o variscan variscan.o statistics.o common.o linefile.o memalloc.o dlist.o errabort.o dystring.o intExp.o kxTok.o pop.o window.o free.o output.o readphylip.o readaxt.o readmga.o readmaf.o readhapmap.o readxmfa.o readmav.o ran1.o swcolumn.o swnet.o swpoly.o swref.o statistics.o: In function `calculate_Fu_and_Li_D': statistics.c:(.text+0x497): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F': statistics.c:(.text+0x569): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_D_star': statistics.c:(.text+0x63b): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F_star': statistics.c:(.text+0x75c): undefined reference to `sqrt' statistics.o: In function `calculate_Tajima_D': statistics.c:(.text+0x85d): undefined reference to `sqrt' statistics.o:statistics.c:(.text+0xcb1): more undefined references to `sqrt' follow statistics.o: In function `calcRunMode21Stats': statistics.c:(.text+0xe02): undefined reference to `log' statistics.o: In function `correctedDivergence': statistics.c:(.text+0xe5a): undefined reference to `log' statistics.o: In function `calcRunMode22Stats': statistics.c:(.text+0x104a): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_fs': statistics.c:(.text+0x11a8): undefined reference to `fabsl' statistics.c:(.text+0x11ca): undefined reference to `powl' statistics.c:(.text+0x11f2): undefined reference to `logl' statistics.o: In function `calculateStatistics': statistics.c:(.text+0x13f2): undefined reference to `log' collect2: ld returned 1 exit status make[1]: *** [variscan] Error 1 make[1]: Leaving directory `/home/avilella/variscan/latest/variscan-2.0.2/src' make: *** [all-recursive] Error 1 The libraries are there because this simple example works perfectly well: $ gcc test.c -o test -lm $ cat test.c #include <stdio.h> #include <math.h> int main(void) { double x = 0.5; double result = sqrt(x); printf("The hyperbolic cosine of %lf is %lf\n", x, result); return 0; } Any ideas?

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  • Make error in installing Math support for MediaWiki

    - by Masi
    How can you solve the following Make error in installing MediaWiki? ... /local/lib/site_perl . /etc/perl /usr/local/lib/perl/5.10.0 /usr/local/share/perl/5.10.0 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.10 /usr/share/perl/5.10 /usr/local/lib/site_perl .) at t/maint/php-tag.t line 8. BEGIN failed--compilation aborted at t/maint/php-tag.t line 8. # Looks like your test died before it could output anything. t/maint/php-tag..........dubious Test returned status 255 (wstat 65280, 0xff00) t/maint/unix-newlines....ok Failed Test Stat Wstat Total Fail List of Failed ------------------------------------------------------------------------------- t/00-test.t 127 32512 ?? ?? ?? t/inc/Database.t 127 32512 ?? ?? ?? t/inc/Global.t 127 32512 ?? ?? ?? t/inc/IP.t 127 32512 ?? ?? ?? t/inc/ImageFunctions.t 127 32512 ?? ?? ?? t/inc/Language.t 127 32512 ?? ?? ?? t/inc/Licenses.t 127 32512 ?? ?? ?? t/inc/LocalFile.t 127 32512 ?? ?? ?? t/inc/Parser.t 127 32512 ?? ?? ?? t/inc/Revision.t 127 32512 ?? ?? ?? t/inc/Sanitizer.t 127 32512 ?? ?? ?? t/inc/Search.t 127 32512 ?? ?? ?? t/inc/Title.t 127 32512 ?? ?? ?? t/inc/Xml.t 127 32512 ?? ?? ?? t/maint/php-lint.t 254 65024 966 966 1-966 t/maint/php-tag.t 255 65280 ?? ?? ?? Failed 16/19 test scripts. 966/4248 subtests failed. Files=19, Tests=4248, 46 wallclock secs (33.15 cusr + 10.38 csys = 43.53 CPU) Failed 16/19 test programs. 966/4248 subtests failed. make: *** [test] Error 255

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  • How can I further optimize this color difference function?

    - by aLfa
    I have made this function to calculate color differences in the CIE Lab colorspace, but it lacks speed. Since I'm not a Java expert, I wonder if any Java guru around has some tips that can improve the speed here. The code is based on the matlab function mentioned in the comment block. /** * Compute the CIEDE2000 color-difference between the sample color with * CIELab coordinates 'sample' and a standard color with CIELab coordinates * 'std' * * Based on the article: * "The CIEDE2000 Color-Difference Formula: Implementation Notes, * Supplementary Test Data, and Mathematical Observations,", G. Sharma, * W. Wu, E. N. Dalal, submitted to Color Research and Application, * January 2004. * available at http://www.ece.rochester.edu/~gsharma/ciede2000/ */ public static double deltaE2000(double[] lab1, double[] lab2) { double L1 = lab1[0]; double a1 = lab1[1]; double b1 = lab1[2]; double L2 = lab2[0]; double a2 = lab2[1]; double b2 = lab2[2]; // Cab = sqrt(a^2 + b^2) double Cab1 = Math.sqrt(a1 * a1 + b1 * b1); double Cab2 = Math.sqrt(a2 * a2 + b2 * b2); // CabAvg = (Cab1 + Cab2) / 2 double CabAvg = (Cab1 + Cab2) / 2; // G = 1 + (1 - sqrt((CabAvg^7) / (CabAvg^7 + 25^7))) / 2 double CabAvg7 = Math.pow(CabAvg, 7); double G = 1 + (1 - Math.sqrt(CabAvg7 / (CabAvg7 + 6103515625.0))) / 2; // ap = G * a double ap1 = G * a1; double ap2 = G * a2; // Cp = sqrt(ap^2 + b^2) double Cp1 = Math.sqrt(ap1 * ap1 + b1 * b1); double Cp2 = Math.sqrt(ap2 * ap2 + b2 * b2); // CpProd = (Cp1 * Cp2) double CpProd = Cp1 * Cp2; // hp1 = atan2(b1, ap1) double hp1 = Math.atan2(b1, ap1); // ensure hue is between 0 and 2pi if (hp1 < 0) { // hp1 = hp1 + 2pi hp1 += 6.283185307179586476925286766559; } // hp2 = atan2(b2, ap2) double hp2 = Math.atan2(b2, ap2); // ensure hue is between 0 and 2pi if (hp2 < 0) { // hp2 = hp2 + 2pi hp2 += 6.283185307179586476925286766559; } // dL = L2 - L1 double dL = L2 - L1; // dC = Cp2 - Cp1 double dC = Cp2 - Cp1; // computation of hue difference double dhp = 0.0; // set hue difference to zero if the product of chromas is zero if (CpProd != 0) { // dhp = hp2 - hp1 dhp = hp2 - hp1; if (dhp > Math.PI) { // dhp = dhp - 2pi dhp -= 6.283185307179586476925286766559; } else if (dhp < -Math.PI) { // dhp = dhp + 2pi dhp += 6.283185307179586476925286766559; } } // dH = 2 * sqrt(CpProd) * sin(dhp / 2) double dH = 2 * Math.sqrt(CpProd) * Math.sin(dhp / 2); // weighting functions // Lp = (L1 + L2) / 2 - 50 double Lp = (L1 + L2) / 2 - 50; // Cp = (Cp1 + Cp2) / 2 double Cp = (Cp1 + Cp2) / 2; // average hue computation // hp = (hp1 + hp2) / 2 double hp = (hp1 + hp2) / 2; // identify positions for which abs hue diff exceeds 180 degrees if (Math.abs(hp1 - hp2) > Math.PI) { // hp = hp - pi hp -= Math.PI; } // ensure hue is between 0 and 2pi if (hp < 0) { // hp = hp + 2pi hp += 6.283185307179586476925286766559; } // LpSqr = Lp^2 double LpSqr = Lp * Lp; // Sl = 1 + 0.015 * LpSqr / sqrt(20 + LpSqr) double Sl = 1 + 0.015 * LpSqr / Math.sqrt(20 + LpSqr); // Sc = 1 + 0.045 * Cp double Sc = 1 + 0.045 * Cp; // T = 1 - 0.17 * cos(hp - pi / 6) + // + 0.24 * cos(2 * hp) + // + 0.32 * cos(3 * hp + pi / 30) - // - 0.20 * cos(4 * hp - 63 * pi / 180) double hphp = hp + hp; double T = 1 - 0.17 * Math.cos(hp - 0.52359877559829887307710723054658) + 0.24 * Math.cos(hphp) + 0.32 * Math.cos(hphp + hp + 0.10471975511965977461542144610932) - 0.20 * Math.cos(hphp + hphp - 1.0995574287564276334619251841478); // Sh = 1 + 0.015 * Cp * T double Sh = 1 + 0.015 * Cp * T; // deltaThetaRad = (pi / 3) * e^-(36 / (5 * pi) * hp - 11)^2 double powerBase = hp - 4.799655442984406; double deltaThetaRad = 1.0471975511965977461542144610932 * Math.exp(-5.25249016001879 * powerBase * powerBase); // Rc = 2 * sqrt((Cp^7) / (Cp^7 + 25^7)) double Cp7 = Math.pow(Cp, 7); double Rc = 2 * Math.sqrt(Cp7 / (Cp7 + 6103515625.0)); // RT = -sin(delthetarad) * Rc double RT = -Math.sin(deltaThetaRad) * Rc; // de00 = sqrt((dL / Sl)^2 + (dC / Sc)^2 + (dH / Sh)^2 + RT * (dC / Sc) * (dH / Sh)) double dLSl = dL / Sl; double dCSc = dC / Sc; double dHSh = dH / Sh; return Math.sqrt(dLSl * dLSl + dCSc * dCSc + dHSh * dHSh + RT * dCSc * dHSh); }

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  • Java algorithm for normalizing audio

    - by Marty Pitt
    I'm trying to normalize an audio file of speech. Specifically, where an audio file contains peaks in volume, I'm trying to level it out, so the quiet sections are louder, and the peaks are quieter. I know very little about audio manipulation, beyond what I've learnt from working on this task. Also, my math is embarrassingly weak. I've done some research, and the Xuggle site provides a sample which shows reducing the volume using the following code: (full version here) @Override public void onAudioSamples(IAudioSamplesEvent event) { // get the raw audio byes and adjust it's value ShortBuffer buffer = event.getAudioSamples().getByteBuffer().asShortBuffer(); for (int i = 0; i < buffer.limit(); ++i) buffer.put(i, (short)(buffer.get(i) * mVolume)); super.onAudioSamples(event); } Here, they modify the bytes in getAudioSamples() by a constant of mVolume. Building on this approach, I've attempted a normalisation modifies the bytes in getAudioSamples() to a normalised value, considering the max/min in the file. (See below for details). I have a simple filter to leave "silence" alone (ie., anything below a value). I'm finding that the output file is very noisy (ie., the quality is seriously degraded). I assume that the error is either in my normalisation algorithim, or the way I manipulate the bytes. However, I'm unsure of where to go next. Here's an abridged version of what I'm currently doing. Step 1: Find peaks in file: Reads the full audio file, and finds this highest and lowest values of buffer.get() for all AudioSamples @Override public void onAudioSamples(IAudioSamplesEvent event) { IAudioSamples audioSamples = event.getAudioSamples(); ShortBuffer buffer = audioSamples.getByteBuffer().asShortBuffer(); short min = Short.MAX_VALUE; short max = Short.MIN_VALUE; for (int i = 0; i < buffer.limit(); ++i) { short value = buffer.get(i); min = (short) Math.min(min, value); max = (short) Math.max(max, value); } // assign of min/max ommitted for brevity. super.onAudioSamples(event); } Step 2: Normalize all values: In a loop similar to step1, replace the buffer with normalized values, calling: buffer.put(i, normalize(buffer.get(i)); public short normalize(short value) { if (isBackgroundNoise(value)) return value; short rawMin = // min from step1 short rawMax = // max from step1 short targetRangeMin = 1000; short targetRangeMax = 8000; int abs = Math.abs(value); double a = (abs - rawMin) * (targetRangeMax - targetRangeMin); double b = (rawMax - rawMin); double result = targetRangeMin + ( a/b ); // Copy the sign of value to result. result = Math.copySign(result,value); return (short) result; } Questions: Is this a valid approach for attempting to normalize an audio file? Is my math in normalize() valid? Why would this cause the file to become noisy, where a similar approach in the demo code doesn't?

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