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  • Please help, now I have a matrix, I want use Combination algorithm to generate a array for length 6

    - by user313429
    The first thanks a lot for your help , the following is my matrix, I want to implement combination algorithm between multiple arrays in LINQ for this matrix. int[,] cj = { { 10, 23, 16, 20 }, { 22, 13, 1, 33 }, { 7, 19, 31, 12 }, { 30, 14, 21, 4 }, { 2, 29, 32, 6 }, { 18, 26, 17, 8 }, { 25, 11, 5, 28 }, { 24, 3, 15, 27 } }; other: public static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> elements, int k) { return k == 0 ? new[] { new T[0] } : elements.SelectMany((e, i) => elements.Skip(i + 1).**Combinations**(k - 1).Select(c => (new[] { e }).Concat(c))); } The above method has a error in my project, System.Collections.Generic.IEnumerable' does not contain a definition for 'Combinations' and no extension method 'Combinations' accepting a first argument of type 'System.Collections.Generic.IEnumerable' could be found (are you missing a using directive or an assembly reference? I use .Net Framework3.5, what is the reason it?

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  • mystified by qr.Q(): what is an orthonormal matrix in "compact" form?

    - by gappy
    R has a qr() function, which performs QR decomposition using either LINPACK or LAPACK (in my experience, the latter is 5% faster). The main object returned is a matrix "qr" that contains in the upper triangular matrix R (i.e. R=qr[upper.tri(qr)]). So far so good. The lower triangular part of qr contains Q "in compact form". One can extract Q from the qr decomposition by using qr.Q(). I would like to find the inverse of qr.Q(). In other word, I do have Q and R, and would like to put them in a "qr" object. R is trivial but Q is not. The goal is to apply to it qr.solve(), which is much faster than solve() on large systems.

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  • How MVC (ASP.NET MVC) band 3-tier architecture can work together?

    - by Martin
    I am writing a design document and people on my team are willing to do the move from ASP.NET WebForm to ASP.NET MVC. This is great, but I have a hard time to understand how MVC workswith in a 3-tier (Data Layer, Business Layer and Presentation Layer) architecture. Can we say that the Model, View and Controller are part of the Presentation Layer? Is the Model part of the Business Layer? In brief, how MVC and 3-tier architecture can work together? Thanks for the help!

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  • Operator + for matrices in C++

    - by cibercitizen1
    I suppose the naive implementation of a + operator for matrices (2D for instance) in C++ would be: class Matrix { Matrix operator+ (Matrix other) const { Matrix result; // fill result with *this.data plus other.data return result; } } so we could use it like Matrix a; Matrix b; Matrix c; c = a + b; Right? But if matrices are big this is not efficient as we are doing one not-necessary copy (return result). Therefore, If we wan't to be efficient we have to forget the clean call: c = a + b; Right? What would you suggest / prefer ? Thanks.

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  • Validating an Autocomplete field in Django

    - by anonymous coward
    I have models similar to the following: class Band(models.Model): name = models.CharField(unique=True) class Event(models.Model): name = models.CharField(max_length=50, unique=True) bands = models.ManyToManyField(Band) and essentially I want to use the validation capability offered by a ModelForm that already exists for Event, but I do not want to show the default Multi-Select list (for 'bands') on the page, because the potential length of the related models is extremely long. I have the following form defined: class AddEventForm(ModelForm): class Meta: model = Event fields = ('name', ) Which does what is expected for the Model, but of course, validation could care less about the 'bands' field. I've got it working enough to add bands correctly, but there's no correct validation, and it will simply drop bad band IDs. What should I do so that I can ensure that at least one (correct) band ID has been sent along with my form? For how I'm sending the band-IDs with auto-complete, see this related question: http://stackoverflow.com/questions/1528059/

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  • How to create dynamic Scatter Plot/Matrix with labels and categories on both axis in Excel 2010?

    - by user1581900
    Let us consider a following data set: Name | Age | Hair Color ----------------------------- John | Young | Brown Sophie | Old | Blond Adam | Mature| Blond Mark | Teen | Dark Jeremy | Old | Grey Alex | Young | Brown etc... Both Age and Hair Color, can take only defined values(Young/teen/mature/old and Blond/brown/Dark/Grey). Name is the only real variable here. I want to create a Scatter Plot / Matrix that will look something like that: I know that I schould use this tool to add labels to the scatter plot. I also found this youtube video that explains how to display categories on Y-axis Moreover I need the chart to be dynamic as explained in another youtube video. How do I combine all these approaches to get a Scatter Plot with categories as values on both axis?

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  • Inverted textures

    - by brainydexter
    I'm trying to draw textures aligned with this physics body whose coordinate system's origin is at the center of the screen. (XNA)Spritebatch has its default origin set to top-left corner. I got the textures to be positioned correctly, but I noticed my textures are vertically inverted. That is, an arrow texture pointing Up , when rendered points down. I'm not sure where I am going wrong with the math. My approach is to convert everything in physic's meter units and draw accordingly. Matrix proj = Matrix.CreateOrthographic(scale * graphics.GraphicsDevice.Viewport.AspectRatio, scale, 0, 1); Matrix view = Matrix.Identity; effect.World = Matrix.Identity; effect.View = view; effect.Projection = proj; effect.TextureEnabled = true; effect.VertexColorEnabled = true; effect.Techniques[0].Passes[0].Apply(); SpriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend, null, DepthStencilState.Default, RasterizerState.CullNone, effect); m_Paddles[1].Draw(gameTime); SpriteBatch.End(); where Paddle::Draw looks like: SpriteBatch.Draw(paddleTexture, mBody.Position, null, Color.White, 0f, new Vector2(16f, 16f), // origin of the texture 0.1875f, SpriteEffects.None, // width of box is 3*2 = 6 meters. texture is 32 pixels wide. to make it 6 meters wide in world space: 6/32 = 0.1875f 0); The orthographic projection matrix seem fine to me, but I am obviously doing something wrong somewhere! Can someone please help me figure out what am i doing wrong here ? Thanks

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  • Converting world space coordinate to screen space coordinate and getting incorrect range of values

    - by user1423893
    I'm attempting to convert from world space coordinates to screen space coordinates. I have the following code to transform my object position Vector3 screenSpacePoint = Vector3.Transform(object.WorldPosition, camera.ViewProjectionMatrix); The value does not appear to be in screen space coordinates and is not limited to a [-1, 1] range. What step have I missed out in the conversion process? EDIT: Projection Matrix Perspective(game.GraphicsDevice.Viewport.AspectRatio, nearClipPlaneZ, farClipPlaneZ); private void Perspective(float aspect_Ratio, float z_NearClipPlane, float z_FarClipPlane) { nearClipPlaneZ = z_NearClipPlane; farClipPlaneZ = z_FarClipPlane; float yZoom = 1f / (float)Math.Tan(fov * 0.5f); float xZoom = yZoom / aspect_Ratio; matrix_Projection.M11 = xZoom; matrix_Projection.M12 = 0f; matrix_Projection.M13 = 0f; matrix_Projection.M14 = 0f; matrix_Projection.M21 = 0f; matrix_Projection.M22 = yZoom; matrix_Projection.M23 = 0f; matrix_Projection.M24 = 0f; matrix_Projection.M31 = 0f; matrix_Projection.M32 = 0f; matrix_Projection.M33 = z_FarClipPlane / (nearClipPlaneZ - farClipPlaneZ); matrix_Projection.M34 = -1f; matrix_Projection.M41 = 0f; matrix_Projection.M42 = 0f; matrix_Projection.M43 = (nearClipPlaneZ * farClipPlaneZ) / (nearClipPlaneZ - farClipPlaneZ); matrix_Projection.M44 = 0f; } View Matrix // Make our view matrix Matrix.CreateFromQuaternion(ref orientation, out matrix_View); matrix_View.M41 = -Vector3.Dot(Right, position); matrix_View.M42 = -Vector3.Dot(Up, position); matrix_View.M43 = Vector3.Dot(Forward, position); matrix_View.M44 = 1f; // Create the combined view-projection matrix Matrix.Multiply(ref matrix_View, ref matrix_Projection, out matrix_ViewProj); // Update the bounding frustum boundingFrustum.SetMatrix(matrix_ViewProj);

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  • How to handle multiple effect files in XNA

    - by Adam 'Pi' Burch
    So I'm using ModelMesh and it's built in Effects parameter to draw a mesh with some shaders I'm playing with. I have a simple GUI that lets me change these parameters to my heart's desire. My question is, how do I handle shaders that have unique parameters? For example, I want a 'shiny' parameter that affects shaders with Phong-type specular components, but for an environment mapping shader such a parameter doesn't make a lot of sense. How I have it right now is that every time I call the ModelMesh's Draw() function, I set all the Effect parameters as so foreach (ModelMesh m in model.Meshes) { if (isDrawBunny == true)//Slightly change the way the world matrix is calculated if using the bunny object, since it is not quite centered in object space { world = boneTransforms[m.ParentBone.Index] * Matrix.CreateScale(scale) * rotation * Matrix.CreateTranslation(position + bunnyPositionTransform); } else //If not rendering the bunny, draw normally { world = boneTransforms[m.ParentBone.Index] * Matrix.CreateScale(scale) * rotation * Matrix.CreateTranslation(position); } foreach (Effect e in m.Effects) { Matrix ViewProjection = camera.ViewMatrix * camera.ProjectionMatrix; e.Parameters["ViewProjection"].SetValue(ViewProjection); e.Parameters["World"].SetValue(world); e.Parameters["diffuseLightPosition"].SetValue(lightPositionW); e.Parameters["CameraPosition"].SetValue(camera.Position); e.Parameters["LightColor"].SetValue(lightColor); e.Parameters["MaterialColor"].SetValue(materialColor); e.Parameters["shininess"].SetValue(shininess); //e.Parameters //e.Parameters["normal"] } m.Draw(); Note the prescience of the example! The solutions I've thought of involve preloading all the shaders, and updating the unique parameters as needed. So my question is, is there a best practice I'm missing here? Is there a way to pull the parameters a given Effect needs from that Effect? Thank you all for your time!

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  • vector rotations for branches of a 3d tree

    - by freefallr
    I'm attempting to create a 3d tree procedurally. I'm hoping that someone can check my vector rotation maths, as I'm a bit confused. I'm using an l-system (a recursive algorithm for generating branches). The trunk of the tree is the root node. It's orientation is aligned to the y axis. In the next iteration of the tree (e.g. the first branches), I might create a branch that is oriented say by +10 degrees in the X axis and a similar amount in the Z axis, relative to the trunk. I know that I should keep a rotation matrix at each branch, so that it can be applied to child branches, along with any modifications to the child branch. My questions then: for the trunk, the rotation matrix - is that just the identity matrix * initial orientation vector ? for the first branch (and subsequent branches) - I'll "inherit" the rotation matrix of the parent branch, and apply x and z rotations to that also. e.g. using glm::normalize; using glm::rotateX; using glm::vec4; using glm::mat4; using glm::rotate; vec4 vYAxis = vec4(0.0f, 1.0f, 0.0f, 0.0f); vec4 vInitial = normalize( rotateX( vYAxis, 10.0f ) ); mat4 mRotation = mat4(1.0); // trunk rotation matrix = identity * initial orientation vector mRotation *= vInitial; // first branch = parent rotation matrix * this branches rotations mRotation *= rotate( 10.0f, 1.0f, 0.0f, 0.0f ); // x rotation mRotation *= rotate( 10.0f, 0.0f, 0.0f, 1.0f ); // z rotation Are my maths and approach correct, or am I completely wrong? Finally, I'm using the glm library with OpenGL / C++ for this. Is the order of x rotation and z rotation important?

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  • XNA, how to draw two cubes standing in line parallelly?

    - by user3535716
    I just got a problem with drawing two 3D cubes standing in line. In my code, I made a cube class, and in the game1 class, I built two cubes, A on the right side, B on the left side. I also setup an FPS camera in the 3D world. The problem is if I draw cube B first(Blue), and move the camera to the left side to cube B, A(Red) is still standing in front of B, which is apparently wrong. I guess some pics can make much sense. Then, I move the camera to the other side, the situation is like: This is wrong.... From this view, the red cube, A should be behind the blue one, B.... Could somebody give me help please? This is the draw in the Cube class Matrix center = Matrix.CreateTranslation( new Vector3(-0.5f, -0.5f, -0.5f)); Matrix scale = Matrix.CreateScale(0.5f); Matrix translate = Matrix.CreateTranslation(location); effect.World = center * scale * translate; effect.View = camera.View; effect.Projection = camera.Projection; foreach (EffectPass pass in effect.CurrentTechnique.Passes) { pass.Apply(); device.SetVertexBuffer(cubeBuffer); RasterizerState rs = new RasterizerState(); rs.CullMode = CullMode.None; rs.FillMode = FillMode.Solid; device.RasterizerState = rs; device.DrawPrimitives( PrimitiveType.TriangleList, 0, cubeBuffer.VertexCount / 3); } This is the Draw method in game1 A.Draw(camera, effect); B.Draw(camera, effect); **

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  • Pixel Shader Issues :

    - by Morphex
    I have issues with a pixel shader, my issue is mostly that I get nothing draw on the screen. float4x4 MVP; // TODO: add effect parameters here. struct VertexShaderInput { float4 Position : POSITION; float4 normal : NORMAL; float2 TEXCOORD : TEXCOORD; }; struct VertexShaderOutput { float4 Position : POSITION; }; VertexShaderOutput VertexShaderFunction(VertexShaderInput input) { input.Position.w = 0; VertexShaderOutput output; output.Position = mul(input.Position, MVP); // TODO: add your vertex shader code here. return output; } float4 PixelShaderFunction(VertexShaderOutput input) : SV_TARGET { return float4(1, 0, 0, 1); } technique { pass { Profile = 11.0; VertexShader = VertexShaderFunction; PixelShader = PixelShaderFunction; } } My matrix is calculated like this : Matrix MVP = Matrix.Multiply(Matrix.Multiply(Matrix.Identity, Matrix.LookAtLH(new Vector3(-10, 10, -10), new Vector3(0), new Vector3(0, 1, -0))), Camera.Projection); VoxelEffect.Parameters["MVP"].SetValue(MVP); Visual Studio Graphics Debug shows me that my vertex shader is actually working, but not the PixelShader. I striped the Shader to the bare minimums so that I was sure the shader was correct. But why is my screen still black?

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  • XNA - Mouse coordinates to word space transformation

    - by Gabriel Butcher
    I have a pretty annoying problem. I would like to create a drawing program, using winform + XNA combo. The most important part would be to transform the mouse position into the XNA drawn grid - I was able to make it for the translations, but it only work if I don't zoom in - when I do, the coordinates simply went horrible wrong. And I have no idea what I doing wrong. I tried to transform with scaling matrix, transform with inverse scaling matrix, multiplying with zoom, but none seems to work. In the beginning (with zoom value = 1) the grid starts from (0,0,0) going to (Width, Height, 0). I was able to get coordinates based on this grid as long as the zoom value didn't changed at all. I using a custom shader, with orthographic projection matrix, identity view matrix, and the transformed world matrix. Here is the two main method: internal void Update(RenderData data) { KeyboardState keyS = Keyboard.GetState(); MouseState mouS = Mouse.GetState(); if (ButtonState.Pressed == mouS.RightButton) { camTarget.X -= (float)(mouS.X - oldMstate.X) / 2; camTarget.Y += (float)(mouS.Y - oldMstate.Y) / 2; } if (ButtonState.Pressed == mouS.MiddleButton || keyS.IsKeyDown(Keys.Space)) { zVal += (float)(mouS.Y - oldMstate.Y) / 10; zoom = (float)Math.Pow(2, zVal); } oldKState = keyS; oldMstate = mouS; world = Matrix.CreateTranslation(new Vector3(-camTarget.X, -camTarget.Y, 0)) * Matrix.CreateScale(zoom / 2); } internal PointF MousePos { get { Vector2 mousePos = new Vector2(Mouse.GetState().X, Mouse.GetState().Y); Matrix trans = Matrix.CreateTranslation(new Vector3(camTarget.X - (Width / 2), -camTarget.Y + (Height / 2), 0)); mousePos = Vector2.Transform(mousePos, trans); return new PointF(mousePos.X, mousePos.Y); } } The second method should return the coordinates of the mouse cursor based on the grid (where the (0,0) point of the grid is the top-left corner.). But is just don't work. I deleted the zoom transformation from the matrix trans, as I didnt was able to get any useful result (most of the time, the coordinates was horrible wrong, mostly many thousand when the grid's size is 500x500). Any idea, or suggestion? I trying to solve this simple problem for two days now :\

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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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  • Rails problem with Delayed_Job and Active Record

    - by Michael Waxman
    I'm using Delayed_Job to grab a Twitter user's data from the API, but it's not saving it in the model for some reason! Please help! (code below) class BandJob < Struct.new(:band_id, :band_username) #parameter def perform require 'json' require 'open-uri' band = Band.find_by_id(band_id) t = JSON.parse(open("http://twitter.com/users/show/#{band_username}.json").read) band.screen_name = t['screen_name'] band.profile_background_image = t['profile_background_image_url'] band.url = 'http://' + band_username + '.com' band.save! end end To clarify, I'm actually not getting any errors, it's just not saving. Here's what my log looks like: * [JOB] acquiring lock on BandJob [4;36;1mDelayed::Job Update (3.1ms)[0m [0;1mUPDATE "delayed_jobs" SET locked_at = '2009-11-09 18:59:45', locked_by = 'host:dhcp128036151228.central.yale.edu pid:2864' WHERE (id = 10442 and (locked_at is null or locked_at < '2009-11-09 14:59:45') and (run_at <= '2009-11-09 18:59:45')) [0m [4;35;1mBand Load (1.5ms)[0m [0mSELECT * FROM "bands" WHERE ("bands"."id" = 34) LIMIT 1[0m [4;36;1mBand Update (0.6ms)[0m [0;1mUPDATE "bands" SET "updated_at" = '2009-11-09 18:59:45', "profile_background_image" = 'http://a3.twimg.com/profile_background_images/38193417/fbtile4.jpg', "url" = 'http://Coldplay.com', "screen_name" = 'coldplay' WHERE "id" = 34[0m [4;35;1mDelayed::Job Destroy (0.5ms)[0m [0mDELETE FROM "delayed_jobs" WHERE "id" = 10442[0m * [JOB] BandJob completed after 0.5448 1 jobs processed at 1.8011 j/s, 0 failed ... Thanks!

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  • Searching For A Record After A LINQ query

    - by Justin
    I'm confused to why this is happening. I'm new to LINQ so I'm clearly missing something here, that is probably pretty easy. I've looked up help on the topic, but I don't really know what to ask so I haven't found any answers that really address my question. This doesn't work It throws an EntityCommandExecutionException when the FirstOrDefault method is executed. var query = from band in context.BandsEntitySet where band.ID == 12345 select band; string venueName = "Willis Park"; foreach (var item in query) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } This works var query = from band in context.BandsEntitySet where band.ID == 12345 select band; var bandList = query.toList(); string venueName = "Willis Park"; foreach (var item in bandList) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } My question is simple: Why is the exception being thrown? And why does creating a list from the query allow me to use the FirstOrDefault method? Exception Message: A first chance exception of type 'System.Data.EntityCommandExecutionException' occurred in System.Data.Entity.dll I guess I am wrong in my assumption that query is a list? Then what is it exactly? I'm confused because this doesn't throw an exception: foreach (var item in query) { var area = item.VenueArea; } I'd appreciate any help on this issue. thanks, Justin

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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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  • 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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  • 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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