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  • Cycle backwards through NSArray

    - by dot
    Hello! I'm trying to cycle backwards through an array by clicking a button. My current code is close, but doesn't quite work. - (void)viewDidLoad { self.imageNames = [NSArray arrayWithObjects:@"MyFirstImage", @"AnotherImage", nil]; currentImageIndex = 0; [super viewDidLoad]; } ...what works: - (IBAction)change { UIImage* imageToShow = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:[imageNames objectAtIndex:currentImageIndex] ofType:@"png"]; currentImageIndex++; if (currentImageIndex >= imageNames.count) { currentImageIndex = 0; } } ...and what isn't working: - (IBAction)changeBack { UIImage* imageToShow = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:[imageNames objectAtIndex:currentImageIndex] ofType:@"png"]; currentImageIndex--; if (currentImageIndex >= imageNames.count) { currentImageIndex = 0; } } Any help is gladly appreciated! Thanks!

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  • Equivalent of object using literal notation

    - by brz dot net
    See following class: function availItem(xs, s, m, l, xl) { this.xs = xs; this.s = s; this.m = m; this.l = l; this.xl = xl; } How can I declare the above class using JSON? I think It should be in following manner but problem is to pass argument. var availItem = { xs : xs, s : s, m : m, l : l, xl : xl } I want to use both in same manner like var obj =new availItem(xs,s,b,l,xl);

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  • Dynamic Links in that auto navigates to the top of a div

    - by Dot Oyes
    I have a forum whereby links to a thread looks like http://www.website.com/comments.php?topic_id=1 How can I make it look like this http://www.website.com/1046302/some-link-desc#12154109 so that when such links are given out, the user is taken directly to that particular comment. I'm particular about the #12154109 . The other part of the URL /1046302/some-link-desc is achieved through .htaccess configuration.

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  • equivalent of javascript class using JSON

    - by brz dot net
    See following class: function availItem(xs, s, m, l, xl) { this.xs = xs; this.s = s; this.m = m; this.l = l; this.xl = xl; } How can I declare the above class using JSON? I think It should be in following manner but problem is to pass argument. var availItem = { xs : xs, s : s, m : m, l : l, xl : xl }

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  • Prevent WPF control from expanding beyond viewable area

    - by Dan dot net
    I have an Items Control in my user control with a scroll viewer around it for when it gets too big (Too big being content is larger than the viewable area of the user control). The problem is that the grid that it is all in just keeps expanding so that the scroll viewer never kicks in (unless I specify an exact height for the grid). See code below and thanks in advance. <Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Height="300px"> <Grid.RowDefinitions> <RowDefinition Height="*" /> </Grid.RowDefinitions> <GroupBox FontWeight="Bold" Header="Tables" Padding="2"> <ScrollViewer> <ItemsControl FontWeight="Normal" ItemsSource="{Binding Path=AvailableTables}"> <ItemsControl.ItemTemplate> <DataTemplate> <CheckBox Content="{Binding Path=DisplayName}" IsChecked="{Binding Path=IsSelected}" Margin="2,3.5" /> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> </ScrollViewer> </GroupBox> </Grid> I would like to not specify the height.

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  • Strange Array#each Ruby behaviour

    - by with a dot.
    The question is a bit vague, but I am not really sure why this happens: I have the following code: p user.room.users.length user.room.users.each {|usr| puts "b" } user.room.users.each {|usr| puts "a"; usr.enter(Room[Config::entrance]) } which outputs: 5 b b b b b a a a I also made User#enter count how many times it's been called and it returns 3! I am completely baffled by this behaviour. I doubt the code within User#enter is the cause, but if someone thinks it might be relevant I can provide it (I don't want to clutter the question unnecessarily). Edit If it's relevant I am using ruby-1.9.3-p125

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  • An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING cla

    - by brz dot net
    I have to find the indentid from the status table based on below two conditions: 1. If there are more than one record having same indentid in status table and the same indentID has count1 in feasibilitystatus table then I don't want to display the record. 2. If there is only one record of indentid in status table and the same indentID has count0 in feasibilitystatus table then I don't want to display the record. Query: select distinct s.indentid from status s where s.status='true' and s.indentid not in(select case when count(s.indentid)>1 then (select indentid from feasibilitystatus group by indentid having count(indentid)>1) else (select indentid from feasibilitystatus group by indentid having count(indentid)>0) end as indentid from status) Error: An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference.

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  • StructureMap DI on Model Assembly

    - by Dan dot net
    I’m new to Dependency Injection and had a question/need guidance. I had an application that used the repository pattern for data access. I used StructureMap to get the correct repository and all worked well. I have since broken out my model (including the repository logic) into its own assembly and added a service layer. In the interest of DI the service layer class takes an IRepository in its constructor. This seems wrong to me as now all consumers of my model need to know about the repository (at least configure their DI to know which one to use). I feel like that is getting into the guts of the model. What sounds wrong with this?

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  • how can i sell hp and ibm server cpu?

    - by elvayee
    i'm now working in a company exporting hp and ibm server cpu. Our price is very competitve, and our quality is very high, also, we have good after sale service. But the problem is: we don't have paid B2B. How can I find customers? if anyone knows, pls contact me by msn : melodyhua123 AT hotmail dot com or elvayee123 at gmail dot com thanks!

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  • How can I create matrices of data in Excel?

    - by sandeep
    I want to create a 4*4 matrix in excel 2007 by taking three or more columns or conditions for example Column index Row index Name 1 2 x 2 3 y 3 4 z 4 1 p this is how data looks and i want it for 1*1 cell as p and 1*2 cell as x and so on. and I want out put as follows matrix 1 2 3 4 1 p x y z 2 p x y z 3 p x y z 4 p x y z and I have very huge data like this some times the matrix size goes up to 60*60 also.

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  • Errors after Google Chrome downgrade

    - by user1933153
    I'm downloaded version 37.0 of Google Chrome but, few plugins and extensions didn't worked. I'm uninstalled that version and install 35.0 again, but now i have some errors. After every Chrome start i get these windows: http://i.imgur.com/rjB1SWJ.png , http://i.imgur.com/gfBa5Ju.png , http:(slash,slash)i(dot)imgur(dot)com/5opKTPE.png And every time i start chrome, i get these errors, it's really annoying, do you have idea how to fix that, or at least hide?

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  • Java code optimization leads to numerical inaccuracies and errors

    - by rano
    I'm trying to implement a version of the Fuzzy C-Means algorithm in Java and I'm trying to do some optimization by computing just once everything that can be computed just once. This is an iterative algorithm and regarding the updating of a matrix, the clusters x pixels membership matrix U, this is the update rule I want to optimize: where the x are the element of a matrix X (pixels x features) and v belongs to the matrix V (clusters x features). And m is a parameter that ranges from 1.1 to infinity. The distance used is the euclidean norm. If I had to implement this formula in a banal way I'd do: for(int i = 0; i < X.length; i++) { int count = 0; for(int j = 0; j < V.length; j++) { double num = D[i][j]; double sumTerms = 0; for(int k = 0; k < V.length; k++) { double thisDistance = D[i][k]; sumTerms += Math.pow(num / thisDistance, (1.0 / (m - 1.0))); } U[i][j] = (float) (1f / sumTerms); } } In this way some optimization is already done, I precomputed all the possible squared distances between X and V and stored them in a matrix D but that is not enough, since I'm cycling througn the elements of V two times resulting in two nested loops. Looking at the formula the numerator of the fraction is independent of the sum so I can compute numerator and denominator independently and the denominator can be computed just once for each pixel. So I came to a solution like this: int nClusters = V.length; double exp = (1.0 / (m - 1.0)); for(int i = 0; i < X.length; i++) { int count = 0; for(int j = 0; j < nClusters; j++) { double distance = D[i][j]; double denominator = D[i][nClusters]; double numerator = Math.pow(distance, exp); U[i][j] = (float) (1f / (numerator * denominator)); } } Where I precomputed the denominator into an additional column of the matrix D while I was computing the distances: for (int i = 0; i < X.length; i++) { for (int j = 0; j < V.length; j++) { double sum = 0; for (int k = 0; k < nDims; k++) { final double d = X[i][k] - V[j][k]; sum += d * d; } D[i][j] = sum; D[i][B.length] += Math.pow(1 / D[i][j], exp); } } By doing so I encounter numerical differences between the 'banal' computation and the second one that leads to different numerical value in U (not in the first iterates but soon enough). I guess that the problem is that exponentiate very small numbers to high values (the elements of U can range from 0.0 to 1.0 and exp , for m = 1.1, is 10) leads to ver y small values, whereas by dividing the numerator and the denominator and THEN exponentiating the result seems to be better numerically. The problem is it involves much more operations. Am I doing something wrong? Is there a possible solution to get both the code optimized and numerically stable? Any suggestion or criticism will be appreciated.

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  • Can't get Jacobi algorithm to work in Objective-C

    - by Chris Long
    Hi, For some reason, I can't get this program to work. I've had other CS majors look at it and they can't figure it out either. This program performs the Jacobi algorithm (you can see step-by-step instructions and a MATLAB implementation here). BTW, it's different from the Wikipedia article of the same name. Since NSArray is one-dimensional, I added a method that makes it act like a two-dimensional C array. After running the Jacobi algorithm many times, the diagonal entries in the NSArray (i[0][0], i[1][1], etc.) are supposed to get bigger and the others approach 0. For some reason though, they all increase exponentially. For instance, i[2][4] should equal 0.0000009, not 9999999, while i[2][2] should be big. Thanks in advance, Chris NSArray+Matrix.m @implementation NSArray (Matrix) @dynamic offValue, transposed; - (double)offValue { double sum = 0.0; for ( MatrixItem *item in self ) if ( item.nonDiagonal ) sum += pow( item.value, 2.0 ); return sum; } - (NSMutableArray *)transposed { NSMutableArray *transpose = [[[NSMutableArray alloc] init] autorelease]; int i, j; for ( i = 0; i < 5; i++ ) { for ( j = 0; j < 5; j++ ) { [transpose addObject:[self objectAtRow:j andColumn:i]]; } } return transpose; } - (id)objectAtRow:(NSUInteger)row andColumn:(NSUInteger)column { NSUInteger index = 5 * row + column; return [self objectAtIndex:index]; } - (NSMutableArray *)multiplyWithMatrix:(NSArray *)array { NSMutableArray *result = [[NSMutableArray alloc] init]; int i = 0, j = 0, k = 0; double value; for ( i = 0; i < 5; i++ ) { value = 0.0; for ( j = 0; j < 5; j++ ) { for ( k = 0; k < 5; k++ ) { MatrixItem *firstItem = [self objectAtRow:i andColumn:k]; MatrixItem *secondItem = [array objectAtRow:k andColumn:j]; value += firstItem.value * secondItem.value; } MatrixItem *item = [[MatrixItem alloc] initWithValue:value]; item.row = i; item.column = j; [result addObject:item]; } } return result; } @end Jacobi_AlgorithmAppDelegate.m // ... - (void)jacobiAlgorithmWithEntry:(MatrixItem *)entry { MatrixItem *b11 = [matrix objectAtRow:entry.row andColumn:entry.row]; MatrixItem *b22 = [matrix objectAtRow:entry.column andColumn:entry.column]; double muPlus = ( b22.value + b11.value ) / 2.0; muPlus += sqrt( pow((b22.value - b11.value), 2.0) + 4.0 * pow(entry.value, 2.0) ); Vector *u1 = [[[Vector alloc] initWithX:(-1.0 * entry.value) andY:(b11.value - muPlus)] autorelease]; [u1 normalize]; Vector *u2 = [[[Vector alloc] initWithX:-u1.y andY:u1.x] autorelease]; NSMutableArray *g = [[[NSMutableArray alloc] init] autorelease]; for ( int i = 0; i <= 24; i++ ) { MatrixItem *item = [[[MatrixItem alloc] init] autorelease]; if ( i == 6*entry.row ) item.value = u1.x; else if ( i == 6*entry.column ) item.value = u2.y; else if ( i == ( 5*entry.row + entry.column ) || i == ( 5*entry.column + entry.row ) ) item.value = u1.y; else if ( i % 6 == 0 ) item.value = 1.0; else item.value = 0.0; [g addObject:item]; } NSMutableArray *firstResult = [[g.transposed multiplyWithMatrix:matrix] autorelease]; matrix = [firstResult multiplyWithMatrix:g]; } // ...

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  • Camera wont stay behind model after pitch, then rotation

    - by ChocoMan
    I have a camera position behind a model. Currently, if I push the left thumbstick making my model move forward, backward, or strafe, the camera stays with the model. If I push the right thumbstick left or right, the model rotates in those directions fine along with the camera rotating while maintaining its position relatively behind the model. But when I pitch the model up or down, then rotate the model afterwards, the camera moves slightly rotates in a clock-like fashion behind the model. If I do a few rotations of the model and try to pitch the camera, the camera will eventually be looking at the side, then eventually the front of the model while also rotating in a clock-like fashion. My question is, how do I keep the camera to pitch up and down behind the model no matter how much the model has rotated? Here is what I got: // Rotates model and pitches camera on its own axis public void modelRotMovement(GamePadState pController) { // Rotates Camera with model Yaw = pController.ThumbSticks.Right.X * MathHelper.ToRadians(angularSpeed); // Pitches Camera around model Pitch = pController.ThumbSticks.Right.Y * MathHelper.ToRadians(angularSpeed); AddRotation = Quaternion.CreateFromYawPitchRoll(Yaw, 0, 0); ModelLoad.MRotation *= AddRotation; MOrientation = Matrix.CreateFromQuaternion(ModelLoad.MRotation); } // Orbit (yaw) Camera around with model (only seeing back of model) public void cameraYaw(Vector3 axisYaw, float yaw) { ModelLoad.CameraPos = Vector3.Transform(ModelLoad.CameraPos - ModelLoad.camTarget, Matrix.CreateFromAxisAngle(axisYaw, yaw)) + ModelLoad.camTarget; } // Raise camera above or below model's shoulders public void cameraPitch(Vector3 axisPitch, float pitch) { ModelLoad.CameraPos = Vector3.Transform(ModelLoad.CameraPos - ModelLoad.camTarget, Matrix.CreateFromAxisAngle(axisPitch, pitch)) + ModelLoad.camTarget; } // Call in update method public void updateCamera() { cameraYaw(Vector3.Up, Yaw); cameraPitch(Vector3.Right, Pitch); } NOTE: I tried to use addPitch just like addRotation but it didn't work...

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  • Keep 3d model facing the camera at all angles

    - by Sparky41
    I'm trying to keep a 3d plane facing the camera at all angles but while i have some success with this: Vector3 gunToCam = cam.cameraPosition - getWorld.Translation; Vector3 beamRight = Vector3.Cross(torpDirection, gunToCam); beamRight.Normalize(); Vector3 beamUp = Vector3.Cross(beamRight, torpDirection); shipeffect.beamWorld = Matrix.Identity; shipeffect.beamWorld.Forward = (torpDirection) * 1f; shipeffect.beamWorld.Right = beamRight; shipeffect.beamWorld.Up = beamUp; shipeffect.beamWorld.Translation = shipeffect.beamPosition; *Note: Logic not wrote by me i just found this rather useful It seems to only face the camera at certain angles. For example if i place the camera behind the plane you can see it that only Roll's around the axis like this: http://i.imgur.com/FOKLx.png (imagine if you are looking from behind where you have fired from. Any idea what to what the problem is (angles are not my specialty) shipeffect is an object that holds this class variables: public Texture2D altBeam; public Model beam; public Matrix beamWorld; public Matrix[] gunTransforms; public Vector3 beamPosition;

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  • Move a 2D square on y axis on android GLES2

    - by Dan
    I am trying to create a simple game for android, to start i am trying to make the square move down the y axis but the way i am doing it dosent move the square at all and i cant find any tutorials for GLES20 The on draw frame function in the render class updates the users position based on accleration dew to gravity, gets the transform matrix from the user class which is used to move the square down, then the program draws it. All that happens is that the square is drawn, no motion happens public void onDrawFrame(GL10 gl) { user.update(0.0, phy.AccelerationDewToGravity); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); // Re draws black background GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, 12, user.SquareVB);//triangleVB); GLES20.glEnableVertexAttribArray(maPositionHandle); GLES20.glUniformMatrix4fv(maPositionHandle, 1, false, user.getTransformMatrix(), 0); GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4); } The update function in the player class is public void update(double vh, double vv) { Vh += vh; // Increase horrzontal Velosity Vv += vv; // Increase vertical velosity //Matrix.translateM(mMMatrix, 0, (int)Vh, (int)Vv, 0); Matrix.translateM(mMMatrix, 0, mMMatrix, 0, (float)Vh, (float)Vv, 0); }

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  • Calculating 3d rotation around random axis

    - by mitim
    This is actually a solved problem, but I want to understand why my original method didn't work (hoping someone with more knowledge can explain). (Keep in mind, I've not very experienced in 3d programming, having only played with the very basic for a little bit...nor do I have a lot of mathematical experience in this area). I wanted to animate a point rotating around another point at a random axis, say a 45 degrees along the y axis (think of an electron around a nucleus). I know how to rotate using the transform matrix along the X, Y and Z axis, but not an arbitrary (45 degree) axis. Eventually after some research I found a suggestion: Rotate the point by -45 degrees around the Z so that it is aligned. Then rotate by some increment along the Y axis, then rotate it back +45 degrees for every frame tick. While this certainly worked, I felt that it seemed to be more work then needed (too many method calls, math, etc) and would probably be pretty slow at runtime with many points to deal with. I thought maybe it was possible to combine all the rotation matrixes involve into 1 rotation matrix and use that as a single operation. Something like: [ cos(-45) -sin(-45) 0] [ sin(-45) cos(-45) 0] rotate by -45 along Z [ 0 0 1] multiply by [ cos(2) 0 -sin(2)] [ 0 1 0 ] rotate by 2 degrees (my increment) along Y [ sin(2) 0 cos(2)] then multiply that result by (in that order) [ cos(45) -sin(45) 0] [ sin(45) cos(45) 0] rotate by 45 along Z [ 0 0 1] I get 1 mess of a matrix of numbers (since I was working with unknowns and 2 angles), but I felt like it should work. It did not and I found a solution on wiki using a different matirx, but that is something else. I'm not sure if maybe I made an error in multiplying, but my question is: this is actually a viable way to solve the problem, to take all the separate transformations, combine them via multiplying, then use that or not?

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  • Managing constant buffers without FX interface

    - by xcrypt
    I am aware that there is a sample on working without FX in the samplebrowser, and I already checked that one. However, some questions arise: In the sample: D3DXMATRIXA16 mWorldViewProj; D3DXMATRIXA16 mWorld; D3DXMATRIXA16 mView; D3DXMATRIXA16 mProj; mWorld = g_World; mView = g_View; mProj = g_Projection; mWorldViewProj = mWorld * mView * mProj; VS_CONSTANT_BUFFER* pConstData; g_pConstantBuffer10->Map( D3D10_MAP_WRITE_DISCARD, NULL, ( void** )&pConstData ); pConstData->mWorldViewProj = mWorldViewProj; pConstData->fTime = fBoundedTime; g_pConstantBuffer10->Unmap(); They are copying their D3DXMATRIX'es to D3DXMATRIXA16. Checked on msdn, these new matrices are 16 byte aligned and optimised for intel pentium 4. So as my first question: 1) Is it necessary to copy matrices to D3DXMATRIXA16 before sending them to the constant buffer? And if no, why don't we just use D3DXMATRIXA16 all the time? I have another question about managing multiple constant buffers within one shader. Suppose that, within your shader, you have multiple constant buffers that need to be updated at different times: cbuffer cbNeverChanges { matrix View; }; cbuffer cbChangeOnResize { matrix Projection; }; cbuffer cbChangesEveryFrame { matrix World; float4 vMeshColor; }; Then how would I set these buffers all at different times? g_pd3dDevice->VSSetConstantBuffers( 0, 1, &g_pConstantBuffer10 ); gives me the possibility to set multiple buffers, but that is within one call. 2) Is that okay even if my constant buffers are updated at different times? And do I suppose I have to make sure the constantbuffers are in the same position in the array as the order they appear in the shader?

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  • Sorting objects before rendering

    - by dreta
    I'm trying to implement a scene graph and in all the articles i've come across there is talk about object sorting. So you'd sort your objects by "material" for example. Now untill i sat down and started implementing it, i kind of took this for granted, because it made sense. But now i'm wondering what does sorting actually change? In my engine, i have a manager for UBOs, i use those to store data that'll be shared between programs, at the moment that only involves time, camera and projection matrices and lights (i'm not worrying about managing which lights affect which objects ATM). Now for each model i have to change the model to world matrix uniform, no sorting is going to change that. So is the jump from changing this matrix to also setting a material for each object that bad? I vaguely remember reading somewhere that each time you change something in the pipeline, it has to get flushed and that can cause performance issues. But for each drawing call i'm setting up a model to world matrix anyway, so what sense does it make to ever be concerned about this? BTW is there any information about whether changing a uniform and calling glBufferSubData is more (or less) expensive.

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  • How to use mount points in MilkShape models?

    - by vividos
    I have bought the Warriors & Commoners model pack from Frogames and the pack contains (among other formats) two animated models and several non-animated objects (axe, shield, pilosities, etc.) in MilkShape3D format. I looked at the official "MilkShape 3D Viewer v2.0" (msViewer2.zip at http://www.chumba.ch/chumbalum-soft/ms3d/download.html) source code and implemented loading the model, calculating the joint matrices and everything looks fine. In the model there are several joints that are designated as the "mount points" for the static objects like axe and shield. I now want to "put" the axe into the hand of the animated model, and I couldn't quite figure out how. I put the animated vertices in a VBO that gets updated every frame (I know I should do this with a shader, but I didn't have time to do this yet). I put the static vertices in another VBO that I want to keep static and not updated every frame. I now tried to render the animated vertices first, then use the joint matrix for the "mount joint" to calculate the location of the static object. I tried many things, and what about seems to be right is to transpose the joint matrix, then use glMatrixMult() to transform the modelview matrix. For some objects like the axe this is working, but not for others, e.g. the pilosities. Now my question: How is this generally implemented when using bone/joint models, and especially with MilkShape3D models? Am I on the right track?

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  • Extracting Frustum Planes (Hartmann & Gribbs method)

    - by DAVco
    I have been grappling with the Hartmann/Gribbs method of extracting the Frustum planes for some time now, with little success. There doesn't appear to be a "definitive" topic or tutorial which combines all the necessary information, so perhaps this can be it First of all, I am attempting to do this in C# (For Playstation Mobile), using OpenGL style Column-Major matrices in a Right-Handed coordinate system but obviously the math will work in any language. My projection matrix has a Near plane at 1.0, Far plane at 1000, FOV of 45.0 and Aspect of 1.7647. I want to get my planes in World-Space, so I build my frustum from the View-Projection Matrix (that's projectionMatrix * viewMatrix). The view Matrix is the inverse of the camera's World-Transform. The problem is; regardless of what I tweak, I can't seem to get a correct frustum. I think that I may be missing something obvious. Focusing on the Near and Far planes for the moment (since they have the most obvious normals when correct), when my camera is positioned looking down the negative z-axis, I get two planes facing in the same direction, rather than opposite directions. If i strafe my camera left and right (while still looking along the z axis) the x value of the normal vector changes. Obviously, something is fundamentally wrong here; I just can't figure out what - maybe someone here can?

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