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  • Layout of mathematical views (iOS)

    - by William Jockusch
    I am trying to figure out the right way to encapsulate graphical information about mathematical objects. It is not simple. For example, a matrix can include square brackets around its entries, or not. Some things carry down to sub-objects -- for example, a matrix might track the font size to be used by its entries. Similarly, the font color and the background color would carry down to the entries. Other things do not carry down. For example, the entries of the matrix do not need to know whether or not the matrix has those square brackets. Based on all of the above, I need to calculate sizes for everything, then frames. All of this can depend on the properties stored above. The size of a matrix depends on the sizes of its entries, and also on whether or not it has those brackets. What I am having a hard time with is not the individual ways to calculate sensible frames for this or that. It is the overall organizational structure of the whole thing. How can I keep track of it all without going crazy. One particular obstacle is worth mentioning -- for reasons I don't want to go into here, I need to calculate the sizes and frames for everything before I instantiate any actual views. So, for example, if I have a Matrix object, I need to calculate its size before I make a MatrixView. If I have an equation, I need to calculate the size of the view for the equation before I create the actual view. So I clearly need separate objects for those calculations. But I can't figure out a sensible class structure for those objects. If I put them all into a single class, I get some advantages because copying then becomes easy. But I also end up with a bloated class that contains info that is irrelevant for some objects -- such as whether or not to include those brackets around the matrix. But if I use a lot of different classes, copying properties becomes a real pain. If it matters, this is all in Objective C, for an iOS environment. Any pointers would be greatly appreciated.

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  • MATLAB: What is an appropriate Data Structure for a Matrix with Random Variable Entries?

    - by user568249
    I'm currently working in an area that is related to simulation and trying to design a data structure that can include random variables within matrices. To motivate this let me say I have the following matrix: [a b; c d] I want to find a data structure that will allow for a, b, c, d to either be real numbers or random variables. As an example, let's say that a = 1, b = -1, c = 2 but let d be a normally distributed random variable with mean 0 and SD 1. The data structure that I have in mind will give no value to d. However, I also want to be able to design a function that can take in the structure, simulate an uniform(0,1), obtain a value for d using an inverse CDF and then spit out an actual matrix. I have several ideas to do this (all related to the MATLAB icdf function) but would like to know how more experienced programmers would do this. In this application, it's important that the structure is as "lean" as possible since I will be working with very very large matrices and memory will be an issue.

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  • Camera frustum calculation coming out wrong

    - by Telanor
    I'm trying to calculate a view/projection/bounding frustum for the 6 directions of a point light and I'm having trouble with the views pointing along the Y axis. Our game uses a right-handed, Y-up system. For the other 4 directions I create the LookAt matrix using (0, 1, 0) as the up vector. Obviously that doesn't work when looking along the Y axis so for those I use an up vector of (-1, 0, 0) for -Y and (1, 0, 0) for +Y. The view matrix seems to come out correctly (and the projection matrix always stays the same), but the bounding frustum is definitely wrong. Can anyone see what I'm doing wrong? This is the code I'm using: camera.Projection = Matrix.PerspectiveFovRH((float)Math.PI / 2, ShadowMapSize / (float)ShadowMapSize, 1, 5); for(var i = 0; i < 6; i++) { var renderTargetView = shadowMap.GetRenderTargetView((TextureCubeFace)i); var up = DetermineLightUp((TextureCubeFace) i); var forward = DirectionToVector((TextureCubeFace) i); camera.View = Matrix.LookAtRH(this.Position, this.Position + forward, up); camera.BoundingFrustum = new BoundingFrustum(camera.View * camera.Projection); } private static Vector3 DirectionToVector(TextureCubeFace direction) { switch (direction) { case TextureCubeFace.NegativeX: return -Vector3.UnitX; case TextureCubeFace.NegativeY: return -Vector3.UnitY; case TextureCubeFace.NegativeZ: return -Vector3.UnitZ; case TextureCubeFace.PositiveX: return Vector3.UnitX; case TextureCubeFace.PositiveY: return Vector3.UnitY; case TextureCubeFace.PositiveZ: return Vector3.UnitZ; default: throw new ArgumentOutOfRangeException("direction"); } } private static Vector3 DetermineLightUp(TextureCubeFace direction) { switch (direction) { case TextureCubeFace.NegativeY: return -Vector3.UnitX; case TextureCubeFace.PositiveY: return Vector3.UnitX; default: return Vector3.UnitY; } } Edit: Here's what the values are coming out to for the PositiveX and PositiveY directions: Constants: Position = {X:0 Y:360 Z:0} camera.Projection = [M11:0.9999999 M12:0 M13:0 M14:0] [M21:0 M22:0.9999999 M23:0 M24:0] [M31:0 M32:0 M33:-1.25 M34:-1] [M41:0 M42:0 M43:-1.25 M44:0] PositiveX: up = {X:0 Y:1 Z:0} target = {X:1 Y:360 Z:0} camera.View = [M11:0 M12:0 M13:-1 M14:0] [M21:0 M22:1 M23:0 M24:0] [M31:1 M32:0 M33:0 M34:0] [M41:0 M42:-360 M43:0 M44:1] camera.BoundingFrustum: Matrix = [M11:0 M12:0 M13:1.25 M14:1] [M21:0 M22:0.9999999 M23:0 M24:0] [M31:0.9999999 M32:0 M33:0 M34:0] [M41:0 M42:-360 M43:-1.25 M44:0] Top = {A:0.7071068 B:-0.7071068 C:0 D:254.5584} Bottom = {A:0.7071068 B:0.7071068 C:0 D:-254.5584} Left = {A:0.7071068 B:0 C:0.7071068 D:0} Right = {A:0.7071068 B:0 C:-0.7071068 D:0} Near = {A:1 B:0 C:0 D:-1} Far = {A:-1 B:0 C:0 D:5} PositiveY: up = {X:0 Y:0 Z:-1} target = {X:0 Y:361 Z:0} camera.View = [M11:-1 M12:0 M13:0 M14:0] [M21:0 M22:0 M23:-1 M24:0] [M31:0 M32:-1 M33:0 M34:0] [M41:0 M42:0 M43:360 M44:1] camera.BoundingFrustum: Matrix = [M11:-0.9999999 M12:0 M13:0 M14:0] [M21:0 M22:0 M23:1.25 M24:1] [M31:0 M32:-0.9999999 M33:0 M34:0] [M41:0 M42:0 M43:-451.25 M44:-360] Top = {A:0 B:0.7071068 C:0.7071068 D:-254.5585} Bottom = {A:0 B:0.7071068 C:-0.7071068 D:-254.5585} Left = {A:-0.7071068 B:0.7071068 C:0 D:-254.5585} Right = {A:0.7071068 B:0.7071068 C:0 D:-254.5585} Near = {A:0 B:1 C:0 D:-361} Far = {A:0 B:-1 C:0 D:365} When I use the resulting BoundingFrustum to cull regions outside of it, this is the result: Pass PositiveX: Drew 3 regions Pass NegativeX: Drew 6 regions Pass PositiveY: Drew 400 regions Pass NegativeY: Drew 36 regions Pass PositiveZ: Drew 3 regions Pass NegativeZ: Drew 6 regions There are only 400 regions to draw and the light is in the center of them. As you can see, the PositiveY direction is drawing every single region. With the near/far planes of the perspective matrix set as small as they are, there's no way a single frustum could contain every single region.

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  • HLSL 5 interpolation issues

    - by metredigm
    I'm having issues with the depth components of my shadowmapping shaders. The shadow map rendering shader is fine, and works very well. The world rendering shader is more problematic. The only value which seems to definitely be off is the pixel's position from the light's perspective, which I pass in parallel to the position. struct Pixel { float4 position : SV_Position; float4 light_pos : TEXCOORD2; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; The reason that I used the semantic 'TEXCOORD2' on the light's pixel position is because I believe that the problem lies with Direct3D's interpolation of values between shaders, and I started trying random semantics and also forcing linear and noperspective interpolations. In the world rendering shader, I observed in the pixel shader that the Z value of light_pos was always extremely close to, but less than the W value. This resulted in a depth result of 0.999 or similar for every pixel. Here is the vertex shader code : struct Vertex { float3 position : POSITION; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; struct Pixel { float4 position : SV_Position; float4 light_pos : TEXCOORD2; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; cbuffer Camera : register (b0) { matrix world; matrix view; matrix projection; }; cbuffer Light : register (b1) { matrix light_world; matrix light_view; matrix light_projection; }; Pixel RenderVertexShader(Vertex input) { Pixel output; output.position = mul(float4(input.position, 1.0f), world); output.position = mul(output.position, view); output.position = mul(output.position, projection); output.world_pos = mul(float4(input.position, 1.0f), world); output.world_pos = mul(output.world_pos, light_view); output.world_pos = mul(output.world_pos, light_projection); output.texcoord = input.texcoord; output.normal = input.normal; return output; } I suspect interpolation to be the culprit, as I used the camera matrices in place of the light matrices in the vertex shader, and had the same problem. The problem is evident as both of the same vectors were passed to a pixel from the VS, but only one of them showed a change in the PS. I have already thoroughly debugged the matrices' validity, the cbuffers' validity, and the multiplicative validity. I'm very stumped and have been trying to solve this for quite some time. Misc info : The light projection matrix and the camera projection matrix are the same, generated from D3DXMatrixPerspectiveFovLH(), with an FOV of 60.0f * 3.141f / 180.0f, a near clipping plane of 0.1f, and a far clipping plane of 1000.0f. Any ideas on what is happening? (This is a repost from my question on Stack Overflow)

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  • Finding the heaviest length-constrained path in a weighted Binary Tree

    - by Hristo
    UPDATE I worked out an algorithm that I think runs in O(n*k) running time. Below is the pseudo-code: routine heaviestKPath( T, k ) // create 2D matrix with n rows and k columns with each element = -8 // we make it size k+1 because the 0th column must be all 0s for a later // function to work properly and simplicity in our algorithm matrix = new array[ T.getVertexCount() ][ k + 1 ] (-8); // set all elements in the first column of this matrix = 0 matrix[ n ][ 0 ] = 0; // fill our matrix by traversing the tree traverseToFillMatrix( T.root, k ); // consider a path that would arc over a node globalMaxWeight = -8; findArcs( T.root, k ); return globalMaxWeight end routine // node = the current node; k = the path length; node.lc = node’s left child; // node.rc = node’s right child; node.idx = node’s index (row) in the matrix; // node.lc.wt/node.rc.wt = weight of the edge to left/right child; routine traverseToFillMatrix( node, k ) if (node == null) return; traverseToFillMatrix(node.lc, k ); // recurse left traverseToFillMatrix(node.rc, k ); // recurse right // in the case that a left/right child doesn’t exist, or both, // let’s assume the code is smart enough to handle these cases matrix[ node.idx ][ 1 ] = max( node.lc.wt, node.rc.wt ); for i = 2 to k { // max returns the heavier of the 2 paths matrix[node.idx][i] = max( matrix[node.lc.idx][i-1] + node.lc.wt, matrix[node.rc.idx][i-1] + node.rc.wt); } end routine // node = the current node, k = the path length routine findArcs( node, k ) if (node == null) return; nodeMax = matrix[node.idx][k]; longPath = path[node.idx][k]; i = 1; j = k-1; while ( i+j == k AND i < k ) { left = node.lc.wt + matrix[node.lc.idx][i-1]; right = node.rc.wt + matrix[node.rc.idx][j-1]; if ( left + right > nodeMax ) { nodeMax = left + right; } i++; j--; } // if this node’s max weight is larger than the global max weight, update if ( globalMaxWeight < nodeMax ) { globalMaxWeight = nodeMax; } findArcs( node.lc, k ); // recurse left findArcs( node.rc, k ); // recurse right end routine Let me know what you think. Feedback is welcome. I think have come up with two naive algorithms that find the heaviest length-constrained path in a weighted Binary Tree. Firstly, the description of the algorithm is as follows: given an n-vertex Binary Tree with weighted edges and some value k, find the heaviest path of length k. For both algorithms, I'll need a reference to all vertices so I'll just do a simple traversal of the Tree to have a reference to all vertices, with each vertex having a reference to its left, right, and parent nodes in the tree. Algorithm 1 For this algorithm, I'm basically planning on running DFS from each node in the Tree, with consideration to the fixed path length. In addition, since the path I'm looking for has the potential of going from left subtree to root to right subtree, I will have to consider 3 choices at each node. But this will result in a O(n*3^k) algorithm and I don't like that. Algorithm 2 I'm essentially thinking about using a modified version of Dijkstra's Algorithm in order to consider a fixed path length. Since I'm looking for heaviest and Dijkstra's Algorithm finds the lightest, I'm planning on negating all edge weights before starting the traversal. Actually... this doesn't make sense since I'd have to run Dijkstra's on each node and that doesn't seem very efficient much better than the above algorithm. So I guess my main questions are several. Firstly, do the algorithms I've described above solve the problem at hand? I'm not totally certain the Dijkstra's version will work as Dijkstra's is meant for positive edge values. Now, I am sure there exist more clever/efficient algorithms for this... what is a better algorithm? I've read about "Using spine decompositions to efficiently solve the length-constrained heaviest path problem for trees" but that is really complicated and I don't understand it at all. Are there other algorithms that tackle this problem, maybe not as efficiently as spine decomposition but easier to understand? Thanks.

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  • How to use Devicemotion/Gyroscope to move a dot from center to 8 directions of iphone screen

    - by iSeeker
    I am trying to move a dot at center to 8 directions of iphone screen using Devicemotion such that it moves faster when tilted at a faster rate. Rough sketch is below: I could find a similar implementation in an app called Gyrododge in appstore, i cant figure out how to make it work... Update: This is what i have done so far, but the response is not smooth, and is very jittery.. xdiff and ydiff are the change of device attitude in x and y directions, derived from quatenion implementation. if (currDeviceMotion.rotationRate.x < -2) { NSLog(@"To Top"); if (195+800*ydiff >=193 && 195+800*ydiff <= 197) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (195+800*ydiff >=390 ) { [self.pitchDot setFrame:CGRectMake(150, 390, 20, 20)]; }else if (195+800*ydiff <= 0){ [self.pitchDot setFrame:CGRectMake(150, 0, 20, 20)]; }else if(195+800*ydiff < 194){ [self.pitchDot setFrame:CGRectMake(150, 195+800*ydiff, 20, 20)]; }else if(195+800*ydiff > 196){ [self.pitchDot setFrame:CGRectMake(150, 195+800*ydiff, 20, 20)]; } } }else if (currDeviceMotion.rotationRate.x > 2){ NSLog(@"To Bottom"); if (195+800*ydiff >=193 && 195+800*ydiff <= 197) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (195+800*ydiff >=390 ) { [self.pitchDot setFrame:CGRectMake(150, 390, 20, 20)]; }else if (195+800*ydiff <= 0){ [self.pitchDot setFrame:CGRectMake(150, 0, 20, 20)]; }else if(195+800*ydiff < 194){ [self.pitchDot setFrame:CGRectMake(150, 195+800*ydiff, 20, 20)]; }else if(195+800*ydiff > 196){ [self.pitchDot setFrame:CGRectMake(150, 195+800*ydiff, 20, 20)]; } } }else if (currDeviceMotion.rotationRate.y < -2){ NSLog(@"To Left"); if (150+500*xdiff >= 148 && 150+500*xdiff <=152) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (150+500*xdiff >= 300 ) { [self.pitchDot setFrame:CGRectMake(300, 195, 20, 20)]; }else if (150+500*xdiff <= 0){ [self.pitchDot setFrame:CGRectMake(0, 195, 20, 20)]; }else if(150+500*xdiff < 148){ [self.pitchDot setFrame:CGRectMake(150+500*xdiff, 195, 20, 20)]; }else if(150+500*xdiff > 152){ [self.pitchDot setFrame:CGRectMake(150+500*xdiff, 195, 20, 20)]; } } }else if (currDeviceMotion.rotationRate.y > 2){ NSLog(@"To Right"); if (150+500*xdiff >= 148 && 150+500*xdiff <=152) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (150+500*xdiff >= 300 ) { [self.pitchDot setFrame:CGRectMake(300, 195, 20, 20)]; }else if (150+500*xdiff <= 0){ [self.pitchDot setFrame:CGRectMake(0, 195, 20, 20)]; }else if(150+500*xdiff < 148){ [self.pitchDot setFrame:CGRectMake(150+500*xdiff, 195, 20, 20)]; }else if(150+500*xdiff > 152){ [self.pitchDot setFrame:CGRectMake(150+500*xdiff, 195, 20, 20)]; } } }else if (currDeviceMotion.rotationRate.x < -0.20 && currDeviceMotion.rotationRate.y > 0.20 ){ NSLog(@"To Diagonal Right Top"); if (150+650*xdiff >= 148 && 150+650*xdiff <=152) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (150+650*xdiff >= 300 ) { [self.pitchDot setFrame:CGRectMake(300, 0, 20, 20)]; }else if(150+650*xdiff > 152){ [self.pitchDot setFrame:CGRectMake(150+650*xdiff, 195-1.3*650*xdiff, 20, 20)]; } } }else if (currDeviceMotion.rotationRate.x > 0.20 && currDeviceMotion.rotationRate.y < -0.20 ){ NSLog(@"To Diagonal Left Bottom"); if (150+650*xdiff >= 148 && 150+650*xdiff <=152) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (150+650*xdiff <= 0 ) { [self.pitchDot setFrame:CGRectMake(0, 390, 20, 20)]; }else if(150+650*xdiff < 148){ [self.pitchDot setFrame:CGRectMake(150+650*xdiff, 195-1.3*650*xdiff, 20, 20)]; } } }else if (currDeviceMotion.rotationRate.x < -0.20 && currDeviceMotion.rotationRate.y < -0.20 ){ NSLog(@"To Diagonal Left Top and xdiff is %f",xdiff); if (150+650*xdiff >= 148 && 150+650*xdiff <=152) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (150+650*xdiff <= 0 ) { [self.pitchDot setFrame:CGRectMake(0, 0, 20, 20)]; }else if(150+650*xdiff < 148){ [self.pitchDot setFrame:CGRectMake(150+650*xdiff, 195+1.3*650*xdiff, 20, 20)]; } } }else if (currDeviceMotion.rotationRate.x > 0.20 && currDeviceMotion.rotationRate.y > 0.20 ){ NSLog(@"To Diagonal Right Bottom"); if (150+650*xdiff >= 148 && 150+650*xdiff <=152) { [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; }else{ if (150+650*xdiff >= 300 ) { [self.pitchDot setFrame:CGRectMake(300, 390, 20, 20)]; }else if(150+650*xdiff > 152){ [self.pitchDot setFrame:CGRectMake(150+650*xdiff, 195+1.3*650*xdiff, 20, 20)]; } } }else if((currDeviceMotion.rotationRate.x < 0.20 && currDeviceMotion.rotationRate.x < -0.20) ||(currDeviceMotion.rotationRate.y < 0.20 && currDeviceMotion.rotationRate.y < -0.20) ||(currDeviceMotion.rotationRate.z < 0.20 && currDeviceMotion.rotationRate.z < -0.20)){ [self.rollDot setFrame:CGRectMake(150, 195, 20, 20)]; [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)]; } It could be great if i could make it move like the application i have stated above, called Gyrododge This link also addresses a similar question:Link. Any advice or help is greatly appreciated... Thanks.

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  • Now Customers Can Actually Locate Your Resources with URL Rewriter 2.0 RTW

    - by The Official Microsoft IIS Site
    Today, Microsoft announced the final release of IIS URL Rewriter 2.0 RTW . Now the first reason might be obvious why you would want to rewrite a URL – when you are at a cocktail party with loud music and tasty appetizers and a potential customer asks you where they can get more info on your snazzy new idea. And you proudly blurt out next to their ear over the roar of the bass, “Just go to h-t-t-p colon slash slash w-w-w dot my new idea dot com slash items dot a-s-p-x question mark cat ID equals new...(read more)

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  • Do premium domain names help us with other languages too?

    - by Fabio Milheiro
    It's commonly known that premium domains with one or two relevant keywords may help us improve our rankings in SERPS. But would it be possible that an english premium domain, for example gold.com (no, it's not mine) also helps to drive more non-english traffic (I'm talking about non-english pages ob)? Trying to make my question clear: Let's suppose that I have an english premium domain with a page like this: gold dot com/post/123/gold-is-yellow And decide to have a spanish, portuguese or french version of the site with pages like: gold dot com/es/post/123/el-oro-es-amarillo gold dot com/pt/post/123/o-ouro-e-amarelo gold dot com/fr/post/123/fsdfsdfsdf The fact that my english domain is a premium one and highly relevant for english terms, will also help me to achieve good rankings for non-english searched terms like: oro (spanish) or ouro (portuguese)?

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  • Why do my 512x512 bitmaps look jaggy on Android OpenGL?

    - by Milo Mordaunt
    This is sort of driving me nuts, I've googled and googled and tried everything I can think of, but my sprites still look super blurry and super jaggy. Example: Here: https://docs.google.com/open?id=0Bx9Gbwnv9Hd2TmpiZkFycUNmRTA If you click through to the actual full size image you should see what I mean, it's like it's taking and average of every 5*5 pixels or something, the background looks really blurry and blocky, but the ball is the worst. The clouds look all right for some reason, probably because they're mostly transparent. I know the pngs aren't top notch themselves but hey, I'm no artist! I would imagine it's a problem with either: a. How the pngs are made example sprite (512x512): https://docs.google.com/open?id=0Bx9Gbwnv9Hd2a2RRQlJiQTFJUEE b. How my Matrices work This is the relevant parts of the renderer: public void onDrawFrame(GL10 unused) { if(world != null) { dt = System.currentTimeMillis() - endTime; world.update( (float) dt); // Redraw background color GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT); Matrix.setIdentityM(mvMatrix, 0); Matrix.translateM(mvMatrix, 0, 0f, 0f, 0f); world.draw(mvMatrix, mProjMatrix); endTime = System.currentTimeMillis(); } else { Log.d(TAG, "There is no world...."); } } public void onSurfaceChanged(GL10 unused, int width, int height) { GLES20.glViewport(0, 0, width, height); Matrix.orthoM(mProjMatrix, 0, 0, width /2, 0, height /2, -1.f, 1.f); } And this is what each Quad does when draw is called: public void draw(float[] mvMatrix, float[] pMatrix) { Matrix.setIdentityM(mMatrix, 0); Matrix.setIdentityM(mvMatrix, 0); Matrix.translateM(mMatrix, 0, xPos, yPos, 0.f); Matrix.multiplyMM(mvMatrix, 0, mvMatrix, 0, mMatrix, 0); Matrix.scaleM(mvMatrix, 0, scale, scale, 0f); Matrix.rotateM(mvMatrix, 0, angle, 0f, 0f, -1f); GLES20.glUseProgram(mProgram); posAttr = GLES20.glGetAttribLocation(mProgram, "vPosition"); texAttr = GLES20.glGetAttribLocation(mProgram, "aTexCo"); uSampler = GLES20.glGetUniformLocation(mProgram, "uSampler"); int alphaHandle = GLES20.glGetUniformLocation(mProgram, "alpha"); GLES20.glVertexAttribPointer(posAttr, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, 0, vertexBuffer); GLES20.glVertexAttribPointer(texAttr, 2, GLES20.GL_FLOAT, false, 0, texCoBuffer); GLES20.glEnableVertexAttribArray(posAttr); GLES20.glEnableVertexAttribArray(texAttr); GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture); GLES20.glUniform1i(uSampler, 0); GLES20.glUniform1f(alphaHandle, alpha); mMVMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVMatrix"); mPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uPMatrix"); GLES20.glUniformMatrix4fv(mMVMatrixHandle, 1, false, mvMatrix, 0); GLES20.glUniformMatrix4fv(mPMatrixHandle, 1, false, pMatrix, 0); GLES20.glDrawElements(GLES20.GL_TRIANGLE_STRIP, 4, GLES20.GL_UNSIGNED_SHORT, indicesBuffer); GLES20.glDisableVertexAttribArray(posAttr); GLES20.glDisableVertexAttribArray(texAttr); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0); } c. How my texture loading/blending/shaders setup works Here is the renderer setup: public void onSurfaceCreated(GL10 unused, EGLConfig config) { // Set the background frame color GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); GLES20.glDisable(GLES20.GL_DEPTH_TEST); GLES20.glDepthMask(false); GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA); GLES20.glEnable(GLES20.GL_BLEND); GLES20.glEnable(GLES20.GL_DITHER); } Here is the vertex shader: attribute vec4 vPosition; attribute vec2 aTexCo; varying vec2 vTexCo; uniform mat4 uMVMatrix; uniform mat4 uPMatrix; void main() { gl_Position = uPMatrix * uMVMatrix * vPosition; vTexCo = aTexCo; } And here's the fragment shader: precision mediump float; uniform sampler2D uSampler; uniform vec4 vColor; varying vec2 vTexCo; varying float alpha; void main() { vec4 color = texture2D(uSampler, vec2(vTexCo)); gl_FragColor = color; if(gl_FragColor.a == 0.0) { "discard; } } This is how textures are loaded: private int loadTexture(int rescource) { int[] texture = new int[1]; BitmapFactory.Options opts = new BitmapFactory.Options(); opts.inScaled = false; Bitmap temp = BitmapFactory.decodeResource(context.getResources(), rescource, opts); GLES20.glGenTextures(1, texture, 0); GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture[0]); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR); GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR); GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, temp, 0); GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0); temp.recycle(); return texture[0]; } I'm sure I'm doing about 20,000 things wrong, so I'm really sorry if the problem is blindingly obvious... The test device is a Galaxy Note, running a JellyBean custom ROM, if that matters at all. So the screen resolution is 1280x800, which means... The background is 1024x1024, so yeah it might be a little blurry, but shouldn't be made of lego. Thank you so much, any answer at all would be appreciated.

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  • Unity: parallel vectors and cross product, how to compare vectors

    - by Heisenbug
    I read this post explaining a method to understand if the angle between 2 given vectors and the normal to the plane described by them, is clockwise or anticlockwise: public static AngleDir GetAngleDirection(Vector3 beginDir, Vector3 endDir, Vector3 upDir) { Vector3 cross = Vector3.Cross(beginDir, endDir); float dot = Vector3.Dot(cross, upDir); if (dot > 0.0f) return AngleDir.CLOCK; else if (dot < 0.0f) return AngleDir.ANTICLOCK; return AngleDir.PARALLEL; } After having used it a little bit, I think it's wrong. If I supply the same vector as input (beginDir equal to endDir), the cross product is zero, but the dot product is a little bit more than zero. I think that to fix that I can simply check if the cross product is zero, means that the 2 vectors are parallel, but my code doesn't work. I tried the following solution: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross == Vector.zero) return AngleDir.PARALLEL; And it doesn't work because comparison between Vector.zero and cross is always different from zero (even if cross is actually [0.0f, 0.0f, 0.0f]). I tried also this: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross.magnitude == 0.0f) return AngleDir.PARALLEL; it also fails because magnitude is slightly more than zero. So my question is: given 2 Vector3 in Unity, how to compare them? I need the elegant equivalent version of this: if (beginDir.x == endDir.x && beginDir.y == endDir.y && beginDir.z == endDir.z) return true;

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  • How Microsoft Market DotNet?

    - by Fendy
    I just read an Joel's article about Microsoft's breaking change (non-backwards compatibility) with dot net's introduction. It is interesting and explicitly reflected the condition during that time. But now almost 10 years has passed. The breaking change It is mainly on how bad is Microsoft introducing non-backwards compatibility development tools, such as dot net, instead of improving the already-widely used asp classic or VB6. As much have known, dot net is not natively embedded in windows XP (yes in vista or 7), so in order to use the .net apps, you need to install the .net framework of over 300mb (it's big that day). However, as we see that nowadays many business use .net as their main development tools, with asp.net or mvc as their web-based applications. C# nowadays be one of tops programming languages (the most questions in stackoverflow). The more interesing part is, win32api still alive even there is newer technology out there (and still widely used). Imagine if microsoft does not introduce the breaking change, there will many corporates still uses asp classic or vb-based applications (there still is, but not that much). There are many corporates use additional services such as azure or sharepoint (beside how expensive is it). Please note that I also know there are many flagships applications (maybe adobe's and blizzard's) still use C-based or older language and not porting to newer high-level language. The question How can Microsoft persuade the users to migrate their old applications into dot net? As we have known it is very hard and give no immediate value when rewrite the applications (netscape story), and it is very risky. I am more interested in Microsoft's way and not opinion such as "because dot net is OOP, or dot net is dll-embedable, etc". This question may be constructive, as the technology is vastly changes over times lately. As we can see, Microsoft changes Asp.Net webform to MVC, winform is legacy now, it is starting to change to use windows store rather than basic-installment, touchscreen and later on we will have see-through applications such as google class. And that will be breaking changes. We will need to account portability as an issue nowadays. We will need other than just mere technology choice, but also migration plans. Even maybe as critical as we might need multiplatform language compiler, as approached by Joel's Wasabi. (hey, I read his articles too much!)

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  • Calculate velocity of a bullet ricocheting on a circle

    - by SteveL
    I made a picture to demostrate what I need,basecaly I have a bullet with velocity and I want it to bounce with the correct angle after it hits a circle Solved(look the accepted answer for explain): Vector.vector.set(bullet.vel); //->v Vector.vector2.setDirection(pos, bullet.pos); //->n normal from center of circle to bullet float dot=Vector.vector.dot(Vector.vector2); //->dot product Vector.vector2.mul(dot).mul(2); Vector.vector.sub(Vector.vector2); Vector.vector.y=-Vector.vector.y; //->for some reason i had to invert the y bullet.vel.set(Vector.vector);

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  • Eigenvector computation using OpenCV

    - by Andriyev
    Hi I have this matrix A, representing similarities of pixel intensities of an image. For example: Consider a 10 x 10 image. Matrix A in this case would be of dimension 100 x 100, and element A(i,j) would have a value in the range 0 to 1, representing the similarity of pixel i to j in terms of intensity. I am using OpenCV for image processing and the development environment is C on Linux. Objective is to compute the Eigenvectors of matrix A and I have used the following approach: static CvMat mat, *eigenVec, *eigenVal; static double A[100][100]={}, Ain1D[10000]={}; int cnt=0; //Converting matrix A into a one dimensional array //Reason: That is how cvMat requires it for(i = 0;i < affnDim;i++){ for(j = 0;j < affnDim;j++){ Ain1D[cnt++] = A[i][j]; } } mat = cvMat(100, 100, CV_32FC1, Ain1D); cvEigenVV(&mat, eigenVec, eigenVal, 1e-300); for(i=0;i < 100;i++){ val1 = cvmGet(eigenVal,i,0); //Fetching Eigen Value for(j=0;j < 100;j++){ matX[i][j] = cvmGet(eigenVec,i,j); //Fetching each component of Eigenvector i } } Problem: After execution I get nearly all components of all the Eigenvectors to be zero. I tried different images and also tried populating A with random values between 0 and 1, but the same result. Few of the top eigenvalues returned look like the following: 9805401476911479666115491135488.000000 -9805401476911479666115491135488.000000 -89222871725331592641813413888.000000 89222862280598626902522986496.000000 5255391142666987110400.000000 I am now thinking on the lines of using cvSVD() which performs singular value decomposition of real floating-point matrix and might yield me the eigenvectors. But before that I thought of asking it here. Is there anything absurd in my current approach? Am I using the right API i.e. cvEigenVV() for the right input matrix (my matrix A is a floating point matrix)? cheers

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  • rotate an image aroound a point

    - by Girish
    Hi all, I have an image which is of rectangular dimension, eg 30 x 60 pixels I want to rotate this image around the bottom center of the image, i.e i want to set the pivot in the above example as (15, 60 )pixel. I am using a drawble and matrix to get this done, whatever i try i always end up rotating around center of the image. Code is : Bitmap bitmapOrg = BitmapFactory.decodeFile("/sdcard/DCIM/2010-06-01_15-32-42_821.jpg"); // float angle = (angle + 10.0f)%360.0f; if(null !=bitmapOrg) { int width = bitmapOrg.getWidth(); int height = bitmapOrg.getHeight(); int newWidth = 15; int newHeight = 15; // calculate the scale - in this case = 0.4f float scaleWidth = ((float) newWidth) / width; float scaleHeight = ((float) newHeight) / height; /* Canvas c = new Canvas(bitmapOrg); float px = ; float py; c.rotate(angle, px, py)*/ // createa matrix for the manipulation Matrix matrix = new Matrix(); // resize the bit map matrix.postScale(scaleWidth, scaleHeight); // rotate the Bitmap // matrix.postRotate(45); // recreate the new Bitmap Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0, width, height, matrix, true); // make a Drawable from Bitmap to allow to set the BitMap // to the ImageView, ImageButton or what ever BitmapDrawable bmd = new BitmapDrawable(resizedBitmap); ImageView imageView = new ImageView(this); // set the Drawable on the ImageView imageView.setImageDrawable(bmd); // center the Image imageView.setScaleType(ScaleType.CENTER); // imageView.layout(100, 300, 0, 0); // linLayout.addView(imageView); // add ImageView to the Layout linLayout.addView(imageView, new AbsoluteLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 10, 30 ) ); can anyone let me know how to get this rectified?

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  • How can I apply a PSSM efficiently?

    - by flies
    I am fitting for position specific scoring matrices (PSSM aka Position Specific Weight Matrices). The fit I'm using is like simulated annealing, where I the perturb the PSSM, compare the prediction to experiment and accept the change if it improves agreement. This means I apply the PSSM millions of times per fit; performance is critical. In my particular problem, I'm applying a PSSM for an object of length L (~8 bp) at every position of a DNA sequence of length M (~30 bp) (so there are M-L+1 valid positions). I need an efficient algorithm to apply a PSSM. Can anyone help improve performance? My best idea is to convert the DNA into some kind of a matrix so that applying the PSSM is matrix multiplication. There are efficient linear algebra libraries out there (e.g. BLAS), but I'm not sure how best to turn an M-length DNA sequence into a matrix M x 4 matrix and then apply the PSSM at each position. The solution needs to work for higher order/dinucleotide terms in the PSSM - presumably this means representing the sequence-matrix for mono-nucleotides and separately for dinucleotides. My current solution iterates over each position m, then over each letter in word from m to m+L-1, adding the corresponding term in the matrix. I'm storing the matrix as a multi-dimensional STL vector, and profiling has revealed that a lot of the computation time is just accessing the elements of the PSSM (with similar performance bottlenecks accessing the DNA sequence). If someone has an idea besides matrix multiplication, I'm all ears.

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  • Problem in Building mplsh-run in lshkit

    - by Yijinsei
    Hi guy, been trying out this for quite some time but I'm still unable to built mplsh-run from lshkit Not sure if this would help to explain my situation during the building process /tmp/cc17kth4.o: In function `lshkit::MultiProbeLshRecallTable::reset(lshkit::MultiProbeLshModel, unsigned int, double, double)': mplsh-run.cpp:(.text._ZN6lshkit24MultiProbeLshRecallTable5resetENS_18MultiProbeLshModelEjdd[lshkit::MultiProbeLshRecallTable::reset(lshkit::MultiProbeLshModel, unsigned int, double, double)]+0x230): undefined reference to `lshkit::MultiProbeLshModel::recall(double) const' /tmp/cc17kth4.o: In function `void lshkit::MultiProbeLshIndex<unsigned int>::query_recall<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, float, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&) const': mplsh-run.cpp:(.text._ZNK6lshkit18MultiProbeLshIndexIjE12query_recallINS_11TopkScannerINS_6MatrixIfE8AccessorENS_6metric5l2sqrIfEEEEEEvPKffRT_[void lshkit::MultiProbeLshIndex<unsigned int>::query_recall<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, float, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&) const]+0x2c4): undefined reference to `lshkit::MultiProbeLsh::genProbeSequence(float const*, std::vector<unsigned int, std::allocator<unsigned int> >&, unsigned int) const' /tmp/cc17kth4.o: In function `void lshkit::MultiProbeLshIndex<unsigned int>::query<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, unsigned int, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&)': mplsh-run.cpp:(.text._ZN6lshkit18MultiProbeLshIndexIjE5queryINS_11TopkScannerINS_6MatrixIfE8AccessorENS_6metric5l2sqrIfEEEEEEvPKfjRT_[void lshkit::MultiProbeLshIndex<unsigned int>::query<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, unsigned int, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&)]+0x4a): undefined reference to `lshkit::MultiProbeLsh::genProbeSequence(float const*, std::vector<unsigned int, std::allocator<unsigned int> >&, unsigned int) const' collect2: ld returned 1 exit status the command that i used to built mplsh-run is g++ -I./lshkit/include -L/usr/lib -lm -lgsl -lgslcblas -lboost_program_options-mt mplsh-run.cpp Do you guys have any clue on how I could solve this?

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  • gluLookAt alternative doesn't work

    - by Brammie
    Hey guys. I'm trying to calculate a lookat matrix myself, instead of using gluLookAt(). My problem is that my matrix doesn't work. using the same parameters on gluLookAt does work however. my way of creating a lookat matrix: Vector3 Eye, At, Up; //these should be parameters =) Vector3 zaxis = At - Eye; zaxis.Normalize(); Vector3 xaxis = Vector3::Cross(Up, zaxis); xaxis.Normalize(); Vector3 yaxis = Vector3::Cross(zaxis, xaxis); yaxis.Normalize(); float r[16] = { xaxis.x, yaxis.x, zaxis.x, 0, xaxis.y, yaxis.y, zaxis.y, 0, xaxis.z, yaxis.z, zaxis.z, 0, 0, 0, 0, 1, }; Matrix Rotation; memcpy(Rotation.values, r, sizeof(r)); float t[16] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, -Eye.x, -Eye.y, -Eye.z, 1, }; Matrix Translation; memcpy(Translation.values, t, sizeof(t)); View = Rotation * Translation; // i tried reversing this as well (translation*rotation) now, when i try to use this matrix be calling glMultMatrixf, nothing shows up in my engine, while using the same eye, lookat and up values on gluLookAt works perfect as i said before. glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glMultMatrixf(View); the problem must be in somewhere in the code i posted here, i know the problem is not in my Vector3/Matrix classes, because they work fine when creating a projection matrix.

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  • What does it mean to "preconcat" a matrix in Android?

    - by Brad Hein
    In reviewing: http://developer.android.com/reference/android/graphics/Canvas.html I'm wondering translate(): "preconcat the current matrix with the specified translation" -- what does this mean? I can't find a good definition of "preconcat" anywhere on the internet! The only place I can find it is in the Android Source - I'm starting to wonder if they made it up? :) I'm familiar with "concat" or concatenate, which is to append to, so what is a pre-concat?

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  • Matlab wont extract first row & column because of matrix dimensions !

    - by ZaZu
    Hey guys, I am tracking an object that is thrown in air, and this object governs a parabolic pattern. Im tracking the object through a series of 30 images. I managed to exclude all the background and keep the object apparent, then used its centroid to get its coordinates and plot them. Now im supposed to predict where the object is going to fall, so I used polyfit & polyval .. the problem is, matlab says ??? Index exceeds matrix dimensions. Now the centroid creates its own structure with a row and 2 columns. Everytime the object moves in the loop, it updates the first row only .. Here is part of the code : For N=1:30 . . . x=centroid(1,1); % extract first row and column for x y=centroid(1,2); % extract secnd row and column for x plot_xy=plot(x,y) set(plot_xy,'XData',x(1:N),'YData',y(1:N)); fitting=polyfit(x(1:N),y(1:N),2); parabola=plot(x,nan(23,1)); evaluate=polyval(fitting,x); set(parabola,'YData',evaluate) . . end The error message I get is ??? Index exceeds matrix dimensions. It seems that (1:N) is causing the problems .. I honestly do not know why .. But when I remove N, the object is plotted along with its points, but polyfitting wont work, it gives me an error saying : Warning: Polynomial is not unique; degree >= number of data points. > In polyfit at 72 If I made it (1:N-1) or something, it plots more points before it starts giving me the same error (not unique ...) . Any ideas why ?? Thanks alot !!

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  • Does this data structure have a name? Sort of a "linked matrix"?

    - by Bob
    Let's say I wanted similar functionality to a doubly linked list but needed a matrix instead so that each node was structured like this: public class Node { Node Up, Down, Left, Right; object Value; } Is there a name for such a structure? I've looked through this Wikipedia listing of data structures but didn't see anything similar. Unless I just missed it.

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  • Is there a better way to declare an empty, typed matrix in MATLAB?

    - by Arthur Ward
    Is there a way to "declare" a variable with a particular user-defined type in MATLAB? zeros() only works for built-in numeric types. The only solution I've come up with involves using repmat() to duplicate a dummy object zero times: arr = repmat(myClass(), [1 0]) Without declaring variables this way, any code which does "arr(end+1) = myClass()" has to include a special case for the default empty matrix which is of type double. Have I missed something a little more sensible?

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