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• Alternative to as3isolib?

  - by tedw4rd

  Hi everyone, I've been working on a Flash game that involves an isometric space. I've been using as3isolib for a while now, and I'm less than impressed with how easy it is to use. Whether I'm approaching it the wrong way or it's just not that great to use is a question for another post. Anyways, I've been thinking of a different way to approach the problem of isometric positions, and I think I've got an idea that might work. Essentially, each object that is to be rendered to the iso-space maintains a 3-coordinate position. Those items are then registered with a camera that projects that 3-coordinate position to a 2-coordinate point on the screen according to the math on this Wikipedia article. Then, the MovieClip is added to the stage (or to the camera's MovieClip, perhaps) at that point, and at a child index of the point's y-value. That way, I figure objects that are closer to the camera will be "above" the objects further away, and will get rendered over them. So my question, then, is two-fold: Do you think this idea will work the way I think it will? Are there any existing 3D matrix/vector packages that I should look at? I know there's a Matrix3 class in Flex 3, but we're not using Flex for this game. Thanks!

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• Azure SDK causes Node.js service bus call to run slow

  - by PazoozaTest Pazman

  I am using this piece of code to call the service bus queue from my node.js server running locally using web matrix, I have also upload to windows azure "web sites" and it still performs slowly. var sb1 = azure.createServiceBusService(config.serviceBusNamespace, config.serviceBusAccessKey); sbMessage = { "Entity": { "SerialNumbersToCreate": '0', "SerialNumberSize": config.usageRates[3], "BlobName": 'snvideos' + channel.ChannelTableName, "TableName": 'snvideos' + channel.ChannelTableName } }; sb1.getQueue('serialnumbers', function(error, queue){ if (error === null){ sb1.sendQueueMessage('serialnumbers', JSON.stringify(sbMessage), function(error) { if (!error) res.send(req.query.callback + '({data: ' + JSON.stringify({ success: true, video: newVideo }) + '});'); else res.send(req.query.callback + '({data: ' + JSON.stringify({ success: false }) + '});'); }); } else res.send(req.query.callback + '({data: ' + JSON.stringify({ success: false }) + '});'); }); It can be up to 5 seconds before the server responds back to the client with the return result. When I comment out the sb1.getQueue('serialnumbers', function(error, queue){ and just have it return without sending a queue message it performs in less than 1 second. Why is that? Is my approach to using the azure sdk service bus correct? Any help would be appreciated.

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• How to setup OpenGL camera for a racing game

  - by vian

  I need the view to show the road polygon (a rectangle 3.f * 100.f) with a vanishing point for a road being at 3/4 height of the viewport and the nearest road edge as a viewport's bottom side. See Crazy Taxi game for an example of what I wish to do. I'm using iPhone SDK 3.1.2 default OpenGL ES project template. I setup the projection matrix as follows: glMatrixMode(GL_PROJECTION); glLoadIdentity(); glFrustumf(-2.25f, 2.25f, -1.5f, 1.5f, 0.1f, 1000.0f); Then I use glRotatef to adjust for landscape mode and setup camera. glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glRotatef(-90, 0.0f, 0.0f, 1.0f); const float cameraAngle = 45.0f * M_PI / 180.0f; gluLookAt(0.0f, 2.0f, 0.0f, 0.0f, 0.0f, 100.0f, 0.0f, cos(cameraAngle), sin(cameraAngle)); My road polygon triangle strip is like this: static const GLfloat roadVertices[] = { -1.5f, 0.0f, 0.0f, 1.5f, 0.0f, 0.0f, -1.5f, 0.0f, 100.0f, 1.5f, 0.0f, 100.0f, }; And I can't seem to find the right parameters for gluLookAt. My vanishing point is always at the center of the screen.

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• Matlab - Propagate points orthogonally on to the edge of shape boundaries

  - by Graham

  Hi I have a set of points which I want to propagate on to the edge of shape boundary defined by a binary image. The shape boundary is defined by a 1px wide white edge. I also have the coordinates of these points stored in a 2 row by n column matrix. The shape forms a concave boundary with no holes within itself made of around 2500 points. I want to cast a ray from each point from the set of points in an orthogonal direction and detect at which point it intersects the shape boundary at. What would be the best method to do this? Are there some sort of ray tracing algorithms that could be used? Or would it be a case of taking orthogonal unit vector and multiplying it by a scalar and testing after multiplication if the end point of the vector is outside the shape boundary. When the end point of the unit vector is outside the shape, just find the point of intersection? Thank you very much in advance for any help!

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• How to map coordinates in AxesImage to coordinates in saved image file?

  - by Vebjorn Ljosa

  I use matplotlib to display a matrix of numbers as an image, attach labels along the axes, and save the plot to a PNG file. For the purpose of creating an HTML image map, I need to know the pixel coordinates in the PNG file for a region in the image being displayed by imshow. I have found an example of how to do this with a regular plot, but when I try to do the same with imshow, the mapping is not correct. Here is my code, which saves an image and attempts to print the pixel coordinates of the center of each square on the diagonal: import numpy as np import matplotlib.pyplot as plt fig = plt.figure() ax = fig.add_axes([0.1, 0.1, 0.8, 0.8]) axim = ax.imshow(np.random.random((27,27)), interpolation='nearest') for x, y in axim.get_transform().transform(zip(range(28), range(28))): print int(x), int(fig.get_figheight() * fig.get_dpi() - y) plt.savefig('foo.png', dpi=fig.get_dpi()) Here is the resulting foo.png, shown as a screenshot in order to include the rulers: The output of the script starts and ends as follows: 73 55 92 69 111 83 130 97 149 112 … 509 382 528 396 547 410 566 424 585 439 As you see, the y-coordinates are correct, but the x-coordinates are stretched: they range from 73 to 585 instead of the expected 135 to 506, and they are spaced 19 pixels o.c. instead of the expected 14. What am I doing wrong?

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• C# images cropping,splitting,saving

  - by cheesebunz

  Hi, as stated in subject, i have an image: private Image testing; testing = new Bitmap(@"sampleimg.jpg"); I would like to split it into 3 x 3 matrix meaning 9 images in total and save it.Any tips or tricks to do this simple? I'm using visual studios 2008 and working on smart devices. Tried some ways but i can't get it. This is what i tried: int x = 0; int y = 0; int width = 3; int height = 3; int count = testing.Width / width; Bitmap bmp = new Bitmap(width, height); Graphics g = Graphics.FromImage(bmp); for (int i = 0; i < count; i++) { g.Clear(Color.Transparent); g.DrawImage(testing, new Rectangle(0, 0, width, height), new Rectangle(x, y, width, height), GraphicsUnit.Pixel); bmp.Save(Path.ChangeExtension(@"C\AndrewPictures\", String.Format(".{0}.bmp",i))); x += width; }

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• Suggestions of the easiest algorithms for some Graph operations

  - by Nazgulled

  Hi, The deadline for this project is closing in very quickly and I don't have much time to deal with what it's left. So, instead of looking for the best (and probably more complicated/time consuming) algorithms, I'm looking for the easiest algorithms to implement a few operations on a Graph structure. The operations I'll need to do is as follows: List all users in the graph network given a distance X List all users in the graph network given a distance X and the type of relation Calculate the shortest path between 2 users on the graph network given a type of relation Calculate the maximum distance between 2 users on the graph network Calculate the most distant connected users on the graph network A few notes about my Graph implementation: The edge node has 2 properties, one is of type char and another int. They represent the type of relation and weight, respectively. The Graph is implemented with linked lists, for both the vertices and edges. I mean, each vertex points to the next one and each vertex also points to the head of a different linked list, the edges for that specific vertex. What I know about what I need to do: I don't know if this is the easiest as I said above, but for the shortest path between 2 users, I believe the Dijkstra algorithm is what people seem to recommend pretty often so I think I'm going with that. I've been searching and searching and I'm finding it hard to implement this algorithm, does anyone know of any tutorial or something easy to understand so I can implement this algorithm myself? If possible, with C source code examples, it would help a lot. I see many examples with math notations but that just confuses me even more. Do you think it would help if I "converted" the graph to an adjacency matrix to represent the links weight and relation type? Would it be easier to perform the algorithm on that instead of the linked lists? I could easily implement a function to do that conversion when needed. I'm saying this because I got the feeling it would be easier after reading a couple of pages about the subject, but I could be wrong. I don't have any ideas about the other 4 operations, suggestions?

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• UML Modelling in C++Builder 2010 Professional

  - by Gordon Brandly

  I'd like to do some basic class diagram UML models in the Pro version of C++Builder 2010. Embarcadero has a C++Builder Features Matrix document, one line of which says "UML Code Visualization – at any time, get a UML model view of your source code" and has a check in the "Professional" column of that table -- I assume this means it should be available to me. Yet, when I open an existing project and do a View | Model View, there's nothing in the Model View window. The only diagram I can find is on the Graph tab of the C++ Class Explorer. I wouldn't call that a UML diagram myself -- is that what Embarcadero is referring to? Embarcadero's table shows that many UML diagrams are not available in Pro, but it looks to me like Class Diagrams should be available. Other lines in that same table indicate that both "Full two-way class diagrams with synchronization between code and diagrams" and "Diagram hyper-linking and annotations" are also supposed to be available in Pro. The Class Explorer graph is one-way only as far as I can tell, so I hope they're referring to something else I haven't been able to find so far. Thanks for any insight into this.

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• Trouble with applying a nested loop on a list

  - by user1665355

  I have a list consisting of 3 elements: datalist=list(a=datanew1,b=datanew2,c=datanew3) datalist$a : Inv_ret Firm size leverage Risk Liquidity Equity 17 0.04555968 17.34834 0.1323199 0.011292273 0.02471489 0 48 0.01405835 15.86315 0.6931730 0.002491093 0.12054914 0 109 0.04556252 16.91602 0.1714068 0.006235836 0.01194579 0 159 0.04753472 14.77039 0.3885720 0.007126830 0.06373028 0 301 0.03941040 16.94377 0.1805346 0.005450653 0.01723319 0 datalist$b : Inv_ret Firm size leverage Risk Liquidity Equity 31 0.04020832 18.13300 0.09326265 0.015235240 0.01579559 0.005025379 62 0.04439078 17.84086 0.11016402 0.005486982 0.01266566 0.006559096 123 0.04543250 18.00517 0.12215307 0.011154742 0.01531451 0.002282790 173 0.03960613 16.45457 0.10828643 0.011506857 0.02385191 0.009003780 180 0.03139643 17.57671 0.40063094 0.003447233 0.04530395 0.000000000 datalist$c : Inv_ret Firm size leverage Risk Liquidity Equity 92 0.03081029 19.25359 0.10513159 0.01635201 0.025760806 0.000119744 153 0.03280746 19.90229 0.11731517 0.01443786 0.006769735 0.011999005 210 0.04655847 20.12543 0.11622403 0.01418010 0.003125632 0.003802365 250 0.03301018 20.67197 0.13208234 0.01262499 0.009418828 0.021400052 282 0.04355975 20.03012 0.08588316 0.01918129 0.004213846 0.023657440 I am trying to create a cor.test on the datalist above : Cor.tests=sapply(datalist,function(x){ for(h in 1:length(names(x))){ for(i in 1:length(names(x$h[i]))){ for(j in 1:length(names(x$h[j]))){ cor.test(x$h[,i],x$h[,j])$p.value }}}}) But I get an error : Error in cor.test.default(x$h[, i], x$h[, j]) : 'x' must be a numeric vector Any suggestions about what I am doing wrong? P.S. If I simply have one dataframe, datanew1 : Inv_ret Firm size leverage Risk Liquidity Equity 17 0.04555968 17.34834 0.1323199 0.011292273 0.02471489 0 48 0.01405835 15.86315 0.6931730 0.002491093 0.12054914 0 109 0.04556252 16.91602 0.1714068 0.006235836 0.01194579 0 159 0.04753472 14.77039 0.3885720 0.007126830 0.06373028 0 301 0.03941040 16.94377 0.1805346 0.005450653 0.01723319 0 I use this loop : results=matrix(NA,nrow=6,ncol=6) for(i in 1:length(names(datanew1))){ for(j in 1:length(names(datanew1))){ results[i,j]<-cor.test(datanew1[,i],datanew1[,j])$p.value }} And the output is: results : [,1] [,2] [,3] [,4] [,5] [,6] [1,] 0.000000e+00 7.085663e-09 3.128975e-10 3.018239e-02 4.806400e-10 0.475139526 [2,] 7.085663e-09 0.000000e+00 2.141581e-21 0.000000e+00 2.247825e-20 0.454032499 [3,] 3.128975e-10 2.141581e-21 0.000000e+00 2.485924e-25 2.220446e-16 0.108643838 [4,] 3.018239e-02 0.000000e+00 2.485924e-25 0.000000e+00 5.870007e-15 0.006783324 [5,] 4.806400e-10 2.247825e-20 2.220446e-16 5.870007e-15 0.000000e+00 0.558827862 [6,] 4.751395e-01 4.540325e-01 1.086438e-01 6.783324e-03 5.588279e-01 0.000000000 Which is exactly what I want. But I want to get 3 matrices, one for each element of the datalist above.

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• Need to calculate rotation-vector from Sensor.TYPE_ORIENTATION data

  - by Sponge

  I need to calculate a rotation vector out of the data i get from Sensor.TYPE_ORIENTATION. The sensor data is defined like this: the values have to be recalculated to become a correct 3d position: values[0]: Azimuth, angle between the magnetic north direction and the Y axis, around the Z axis (0 to 359). 0=North, 90=East, 180=South, 270=West values[1]: Pitch, rotation around X axis (-180 to 180), with positive values when the z-axis moves toward the y-axis. values[2]: Roll, rotation around Y axis (-90 to 90), with positive values when the x-axis moves away from the z-axis I need all three values like the Z axis value (from 0 to 360 degree). I tried a lot but cant figure out how to do this :/ i also tried to use Sensor.TYPE_ACCELEROMETER and Sensor.TYPE_MAGNETIC_FIELD to calculate this 3d vector on my own. here is the code: final float[] inR = new float[16]; // load inR matrix from current sensor data: SensorManager.getRotationMatrix(inR, null, gravityValues, geomagneticValues); float[] orientation = new float[3]; SensorManager.getOrientation(inR, orientation); mapMagAndAcclDataToVector(orientation); //here i do some *360 stuff orientetionChanged(orientation); //then the correct values are passed (in theorie) But this didn't work and i think it is much to complicated. So i bet there is a simple solution how to recalc the values of ensor.TYPE_ORIENTATION to make them a 3d rotation vector, but i just dont know how to do it. If you know the answer please tell me.

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• Warshall Algorithm Logic - Stuck

  - by stan

  I am trying to use this logic to understand what is going on with the adjacency matrix, but i am massivley confused where it says about interspacing for a b c d ..... Could anyone explain what is going on here? Thank you (tagged as java as its the language this was demonstarted to us in, so if anyone posted any code examples they could see it was in that language) http://compprog.wordpress.com/2007/11/15/all-sources-shortest-path-the-floyd-warshall-algorithm/ Here is the code: for (k = 0; k < n; ++k) { for (i = 0; i < n; ++i) for (j = 0; j < n; ++j) /* If i and j are different nodes and if the paths between i and k and between k and j exist, do */ if ((dist[i][k] * dist[k][j] != 0) && (i != j)) /* See if you can't get a shorter path between i and j by interspacing k somewhere along the current path */ if ((dist[i][k] + dist[k][j] < dist[i][j]) || (dist[i][j] == 0)) dist[i][j] = dist[i][k] + dist[k][j];

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• Dimension Mismatch MatLab; cant figure out why it is mismatching

  - by Abid

  I think it may be a syntax issue, here is the code. load ([ 'C:\Users\Abid\Desktop\Inquiry Runs\dtS' ]) dtS((dtS==0))=nan; for j=2:9; maxS=max(dtS(j,:)); minS=min(dtS(j,:)); maxval(j,:)=dtS((dtS>(maxS-.1*maxS))); minval(j,:)=dtS((dtS<(minS+.1*minS))); avmax(j)=mean(maxval(j,:)); avmin(j)=mean(minval(j,:)); avs(j,:)=[avmax(j) avmin(j)] end So I know the the row matrices are different sizes every loop. For example maxval(j,:) will change depending one row it is looking through for certain values. I did this manually and I see that on the first loop the matrices are size (1,1), however, if I set the loop to run for only j=2, the row length is 13. Usually if a matrix is changing size on the loop, I only get a warning, but this time I think it is due to a reason I don't understand.

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• Bilinear interpolation - DirectX vs. GDI+

  - by holtavolt

  I have a C# app for which I've written GDI+ code that uses Bitmap/TextureBrush rendering to present 2D images, which can have various image processing functions applied. This code is a new path in an application that mimics existing DX9 code, and they share a common library to perform all vector and matrix (e.g. ViewToWorld/WorldToView) operations. My test bed consists of DX9 output images that I compare against the output of the new GDI+ code. A simple test case that renders to a viewport that matches the Bitmap dimensions (i.e. no zoom or pan) does match pixel-perfect (no binary diff) - but as soon as the image is zoomed up (magnified), I get very minor differences in 5-10% of the pixels. The magnitude of the difference is 1 (occasionally 2)/256. I suspect this is due to interpolation differences. Question: For a DX9 ortho projection (and identity world space), with a camera perpendicular and centered on a textured quad, is it reasonable to expect DirectX.Direct3D.TextureFilter.Linear to generate identical output to a GDI+ TextureBrush filled rectangle/polygon when using the System.Drawing.Drawing2D.InterpolationMode.Bilinear setting? For this (magnification) case, the DX9 code is using this (MinFilter,MipFilter set similarly): Device.SetSamplerState(0, SamplerStageStates.MagFilter, (int)TextureFilter.Linear); and the GDI+ path is using: g.InterpolationMode = InterpolationMode.Bilinear; I thought that "Bilinear Interpolation" was a fairly specific filter definition, but then I noticed that there is another option in GDI+ for "HighQualityBilinear" (which I've tried, with no difference - which makes sense given the description of "added prefiltering for shrinking") Followup Question: Is it reasonable to expect pixel-perfect output matching between DirectX and GDI+ (assuming all external coordinates passed in are equal)? If not, why not? Finally, there are a number of other APIs I could be using (Direct2D, WPF, GDI, etc.) - and this question generally applies to comparing the output of "equivalent" bilinear interpolated output images across any two of these. Thanks!

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• how to create a changing variable for fsolve

  - by Shun Miyamoto

  i want fsolve to calculate the output for different uc each time (increasing uc by 0.001 each time). each output from fsolve should be sent to a simulink model seperatly. so i set a loop to do so, but i believe that at the currenty constellation (if it will work)will just calculate 1000 different values? is there a way to send out the values seperately? if not, how can i create a parameter uc. that goes from 0 to say 1000? i tried uc=0:0.001:1000, but again, the demension doen't seem to fit. how do i create a function that takes the next element of a vector/matrix each time the function is called? uc=0; for i=0:1000 x0=[1,1,1]; y=x0(1); u=x0(2); yc=x0(3); options=optimset('Display','off'); x= fsolve(@myfun,x0,options,uc,d,spacing_amplitude,spacing_width); end best regards

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• How to embed XBase expressions in an Xtext DSL

  - by Marcus Mathioudakis

  I am writing a simple little DSL for specifying constraints on messages, and Have been trying without success for a while to embed XBase expressions into the language. The Grammar looks like this: grammar org.xtext.businessrules.BusinessRules with org.eclipse.xtext.xbase.Xbase //import "http://www.eclipse.org/xtext/xbase/Xbase" as xbase import "http://www.eclipse.org/xtext/common/JavaVMTypes" as jvmTypes generate businessRules "http://www.xtext.org/businessrules/BusinessRules" Start: rules+=Constraint*; Constraint: {Constraint} 'FOR' 'PAYLOAD' payload=PAYLOAD 'ELEMENT' element=ID 'CONSTRAINED BY' constraint=XExpression; PAYLOAD: "SimulationSessionEvents" |"stacons" |"any" ; Range: 'above' min=INT ('below' max=INT)? |'below' max=INT ('above' min=INT)? ; When trying to parse a file such as: FOR PAYLOAD SimulationSessionEvents ELEMENT matrix CONSTRAINED BY ... I can't get it to work for ... = any kind of Arithmetic expression, although it works for ...= loop or if expression, or even just a number. As soon as I do something like '-5' or '4-5' it says Couldn't resolve reference to JvmIdentifiableElement '-', even though the Xbase.xtext Grammar looks like it allows these expressions. I don't think I'm missing any Jars, as it doesn't complain when I run the mwe workflow, but only when trying to parse the input file. Any help would be much appreciated.

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• Tips on designing a .NET API for future use with F#

  - by Drew Noakes

  I'm in the process of designing a .NET API to allow developers to create RoboCup agents for the 3D simulated soccer league. I'm pretty happy with how the API work with C# code, however I would like to use this project to improve my F# skill (which is currently based on reading rather than practice). So I would like to ask what kinds of things I should consider when designing an API that is to be consumed by both C# and F# code. Some points. I make fairly heavy use of matrix and vector math. These are currently immutable classes/structs. The API currently defines a few interfaces with the consumer implements (eg: IAgent), using instances of their implementations (eg: MyAgent) to construct other API classes (eg: new Client(myAgent)). The API fires events. The API exposes a few delegate types. The API includes several enums. I'd like to release a version of the API as soon as possible and don't want to make major changes to it later if I realise it's too difficult to work with from F#. Any advice is appreciated.

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• Which are the RDBMS that minimize the server roundtrips? Which RDBMS are better (in this area) than

  - by user193655

  When the latency is high ("when pinging the server takes time") the server roundtrips make the difference. Now I don't want to focus on the roundtrips created in programming, but the roundtrips that occur "under the hood" in the DB engine, so the roundtrips that are 100% dependant on how the RDBMS is written itself. I have been told that FireBird has more roundtrips than MySQL. But this is the only information I know. I am currently supporting MS SQL but I'd like to change RDBMS (because I use Express Editions and in my scenario they are quite limiting from the performance point of view), so to make a wise choice I would like to include also this point into "my RDBMS comparison feature matrix" to understand which is the best RDBMS to choose as an alternative to MS SQL. So the bold sentence above would make me prefer MySQL to Firebird (for the roundtrips concept, not in general), but can anyone add informations? And MS SQL where is it located? Is someone able to "rank" the roundtrip performance of the main RDBMS, or at least: MS SQL, MySql, Postegresql, Firebird (I am not interested in Oracle since it is not free, and if I have to change I would change to a free RDBMS). Anyway MySql (as mentioned several times on stackoverflow) has a not clear future and a not 100% free license. So my final choice will probably dall on PostgreSQL or Firebird. Additional info: somehow you can answer my question by making a simple list like: MSSQL:3; MySQL:1; Firebird:2; Postgresql:2 (where 1 is good, 2 average, 3 bad). Of course if you can post some links where the roundtrips per RDBMSs are compared it would be great

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• Generic FSM for game in C++ ?

  - by Mr.Gando

  Hello, I was wondering if there's a way I could code some kind of "generic" FSM for a game with C++?. My game has a component oriented design, so I use a FSM Component. my Finite State Machine (FSM) Component, looks more or less this way. class gecFSM : public gecBehaviour { public: //Constructors gecFSM() { state = kEntityState_walk; } gecFSM(kEntityState s) { state = s; } //Interface void setRule(kEntityState initialState, int inputAction, kEntityState resultingState); void performAction(int action); private: kEntityState fsmTable[MAX_STATES][MAX_ACTIONS]; }; I would love to hear your opinions/ideas or suggestions about how to make this FSM component, generic. With generic I mean: 1) Creating the fsmTable from an xml file is really easy, I mean it's just a bunch of integers that can be loaded to create an MAX_STATESxMAX_ACTION matrix. void gecFSM::setRule(kEntityState initialState, int inputAction, kEntityState resultingState) { fsmTable[initialState][inputAction] = resultingState; } 2) But what about the "perform Action" method ? void gecFSM::performAction(int action) { switch( smTable[ ownerEntity->getState() ][ action ] ) { case WALK: /*Walk action*/ break; case STAND: /*Stand action*/ break; case JUMP: /*Jump action*/ break; case RUN: /*Run action*/ break; } } What if I wanted to make the "actions" and the switch generic? This in order to avoid creating a different FSM component class for each GameEntity? (gecFSMZombie, gecFSMDryad, gecFSMBoss etc ?). That would allow me to go "Data Driven" and construct my generic FSM's from files for example. What do you people suggest?

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• Performance: float to int cast and clipping result to range

  - by durandai

  I'm doing some audio processing with float. The result needs to be converted back to PCM samples, and I noticed that the cast from float to int is surprisingly expensive. Whats furthermore frustrating that I need to clip the result to the range of a short (-32768 to 32767). While I would normally instictively assume that this could be assured by simply casting float to short, this fails miserably in Java, since on the bytecode level it results in F2I followed by I2S. So instead of a simple: int sample = (short) flotVal; I needed to resort to this ugly sequence: int sample = (int) floatVal; if (sample > 32767) { sample = 32767; } else if (sample < -32768) { sample = -32768; } Is there a faster way to do this? (about ~6% of the total runtime seems to be spent on casting, while 6% seem to be not that much at first glance, its astounding when I consider that the processing part involves a good chunk of matrix multiplications and IDCT) EDIT The cast/clipping code above is (not surprisingly) in the body of a loop that reads float values from a float[] and puts them into a byte[]. I have a test suite that measures total runtime on several test cases (processing about 200MB of raw audio data). The 6% were concluded from the runtime difference when the cast assignment "int sample = (int) floatVal" was replaced by assigning the loop index to sample. EDIT @leopoldkot: I'm aware of the truncation in Java, as stated in the original question (F2I, I2S bytecode sequence). I only tried the cast to short because I assumed that Java had an F2S bytecode, which it unfortunately does not (comming originally from an 68K assembly background, where a simple "fmove.w FP0, D0" would have done exactly what I wanted).

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• Introduction to vectorizing in MATLAB - any good tutorials?

  - by Gacek

  I'm looking for any good tutorials on vectorizing (loops) in MATLAB. I have quite simple algorithm, but it uses two for loops. I know that it should be simple to vectorize it and I would like to learn how to do it instead of asking you for the solution. But to let you know what problem I have, so you would be able to suggest best tutorials that are showing how to solve similar problems, here's the outline of my problem: B = zeros(size(A)); % //A is a given matrix. for i=1:size(A,1) for j=1:size(A,2) H = ... %// take some surrounding elements of the element at position (i,j) (i.e. using mask 3x3 elements) B(i,j) = computeSth(H); %// compute something on selected elements and place it in B end end So, I'm NOT asking for the solution. I'm asking for a good tutorials, examples of vectorizing loops in MATLAB. I would like to learn how to do it and do it on my own.

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• Who to access a UIButton using tag and button change image?

  - by ste

  I need to change the images on a matrix of UIButtons, and the only thing I know of to address the buttons, is the tag. But I can not find a way to actually us this identifier. The buttons are created programmatically during viewDidLoad. Here is the code for creating the buttons: #define N_ROWS 4 #define N_COLS 3 int N_IMG = 0; for (int a = 0; a < N_COLS; a++) { for (int j = 0; j < N_ROWS; j++) { UIButton *aButton = [UIButton buttonWithType:UIButtonTypeCustom]; aButton.frame = CGRectMake(a * 65.0 + 25, j * 65.0 + 15, 10.0, 10.0); aButton.tag = j + a * N_ROWS + 1; [aButton setBackgroundColor:[UIColor redColor]]; N_IMG = N_IMG++; [self.view addSubview:aButton]; number_sorted = 1; } } Here is the code for setting the image: - (IBAction)set_image:(id)sender { #define N_ROWS 4 #define N_COLS 3 int N_IMG = 0; for (int a = 0; a < N_COLS; a++) { for (int j = 0; j < N_ROWS; j++) { uibutton aButton.tag == (j + a * N_ROWS + 1) setImage:[UIImage imageNamed:[puzzles objectAtIndex:N_IMG]] forState:UIControlStateNormal]; N_IMG = N_IMG++; } } } This is the code where the truble starts: uibutton aButton.tag == (j + a * N_ROWS + 1) Who can I set this up to work?

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• Syntactical analysis with Flex/Bison part 2

  - by Imran

  Hallo, I need help in Lex/Yacc Programming. I wrote a compiler for a syntactical analysis for inputs of many statements. Now i have a special problem. In case of an Input the compiler gives the right output, which statement is uses, constant operator or a jmp instructor to which label, now i have to write so, if now a if statement comes, first the first command (before the else) must be give out when the assignment of the if is yes then it must jump to the end because the command after the else isnt needed, so after this jmp then the second command must be give out. I show it in an example maybe you understand what i mean. Input adr. Output if(x==0) 10 if(x==0) Wait 5 20 WAIT 5 else 30 JMP 50 Wait 1 40 WAIT 1 end 50 END like so. I have an idea, maybe i can do it whith a special if statement like IF exp jmp_stmt_end stmt_seq END when the if statement is given in the input the compiler has to recognize the end ofthe statement and like my jmp_stmt in my compiler ( you have to download the files from http://bitbucket.org/matrix/changed-tiny) only to jump to the end. I hope you understand my problem.thanks.

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• Problem using the find function in MATLAB

  - by Peter Etchells

  I have two arrays of data that I'm trying to amalgamate. One contains actual latencies from an experiment in the first column (e.g. 0.345, 0.455... never more than 3 decimal places), along with other data from that experiment. The other contains what is effectively a 'look up' list of latencies ranging from 0.001 to 0.500 in 0.001 increments, along with other pieces of data. Both data sets are X-by-Y doubles. What I'm trying to do is something like... for i = 1:length(actual_latency) row = find(predicted_data(:,1) == actual_latency(i)) full_set(i,1:4) = [actual_latency(i) other_info(i) predicted_info(row,2) ... predicted_info(row,3)]; end ...in order to find the relevant row in predicted_data where the look up latency corresponds to the actual latency. I then use this to created an amalgamated data set, full_set. I figured this would be really simple, but the find function keeps failing by throwing up an empty matrix when looking for an actual latency that I know is in predicted_data(:,1) (as I've double-checked during debugging). Moreover, if I replace find with a for loop to do the same job, I get a similar error. It doesn't appear to be systematic - using different participant data sets throws it up in different places. Furthermore, during debugging mode, if I use find to try and find a hard-coded value of actual_latency, it doesn't always work. Sometimes yes, sometimes no. I'm really scratching my head over this, so if anyone has any ideas about what might be going on, I'd be really grateful.

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• Python: Serial Transmission

  - by Silent Elektron

  I have an image stack of 500 images (jpeg) of 640x480. I intend to make 500 pixels (1st pixels of all images) as a list and then send that via COM1 to FPGA where I do my further processing. I have a couple of questions here: How do I import all the 500 images at a time into python and how do i store it? How do I send the 500 pixel list via COM1 to FPGA? I tried the following: Converted the jpeg image to intensity values (each pixel is denoted by a number between 0 and 255) in MATLAB, saved the intensity values in a text file, read that file using readlines(). But it became too cumbersome to make the intensity value files for all the 500 images! Used NumPy to put the read files in a matrix and then pick the first pixel of all images. But when I send it, its coming like: [56, 61, 78, ... ,71, 91]. Is there a way to eliminate the [ ] and , while sending the data serially? Thanks in Advance! :)

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• Patterns / Solutions to complicated Feature Management

  - by yclian

  Hi all, My company develops CDN / Web-Hosting solution. We have a middleware that's served as a business logic layer and exposes web service for the front-end. I would like to seek for a clean solution to feature management - there're uncertainties and ugly workarounds/solutions in the software that the dev would say "when it happens or is broken, we will fix it". For example, here're the following features that a web publisher can have: Sites limit Bandwidth limit SSL feature + SSL configuration per site If we downgrade a web publisher, when he's having 10 sites, down to 5 sites, we can choose not to suspend the rest of the 5 sites, or we shall prompt for suspension before the downgrade. For the case of bandwidth limit, the downgrade is easy, when the bandwidth check happens, if the publisher has it exceeded, then we will suspend his account. For the case of SSL feature. Every SSL configuration is tied to a site, what shall happen to these configuration object when the SSL feature is downgraded from enabled to disabled? So as you can see, there're many different situations and there are different ways of handling it. I can make a system that examines the impacts and prompts the user to make changes before the downgrade/upgrade. Or a system that ignores the impacts and just upgrade/downgrade. Bad. Or a system designed in a way that the client code need to be aware of the complex feature matrix (or I can expose a helper to the client code to check if a feature is not DEFUNCT) There can be many ways that I am still thinking but puzzled. I am wondering, how would you tackle this issue and is there any recommended patterns or books or software that you think I can refer to? Appreciate your help.

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