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• Compute directional light frustum from view furstum points and light direction

  - by Fabian

  I'm working on a friends engine project and my task is to construct a new frustum from the light direction that overlaps the view frustum and possible shadow casters. The project already has a function that creates a frustum for this but its way to big and includes way to many casters (shadows) which can't be seen in the view frustum. Now the only parameter of this function are the normalized light direction vector and a view class which lets me extract the 8 view frustum points in world space. I don't have any additional infos about the scene. I have read some of the related Questions here but non seem to fit very well to my problem as they often just point to cascaded shadow maps. Sadly i can't use DX or openGl functions directly because this engine has a dedicated math library. From what i've read so far the steps are: Transform view frustum points into light space and find min/max x and y values (or sometimes minima and maxima of all three axis) and create a AABB using the min/max vectors. But what comes after this step? How do i transform this new AABB back to world space? What i've done so far: CVector3 Points[8], MinLight = CVector3(FLT_MAX), MaxLight = CVector3(FLT_MAX); for(int i = 0; i<8;++i){ Points[i] = Points[i] * WorldToShadowMapMatrix; MinLight = Math::Min(Points[i],MinLight); MaxLight = Math::Max(Points[i],MaxLight); } AABox box(MinLight,MaxLight); I don't think this is the right way to do it. The near plain probably has to extend into the direction of the light source to include potentional shadow casters. I've read the Microsoft article about cascaded shadow maps http://msdn.microsoft.com/en-us/library/windows/desktop/ee416307%28v=vs.85%29.aspx which also includes some sample code. But they seem to use the scenes AABB to determine the near and far plane which I can't since i cant access this information from the funtion I'm working in. Could you guys please link some example code which shows the calculation of such frustum? Thanks in advance! Additional questio: is there a way to construct a WorldToFrustum matrix that represents the above transformation?

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• Car-like Physics - Basic Maths to Simulate Steering

  - by Reanimation

  As my program stands I have a cube which I can control using keyboard input. I can make it move left, right, up, down, back, fourth along the axis only. I can also rotate the cube either left or right; all the translations and rotations are implemented using glm. if (keys[VK_LEFT]) //move cube along xAxis negative { globalPos.x -= moveCube; keys[VK_RIGHT] = false; } if (keys[VK_RIGHT]) //move cube along xAxis positive { globalPos.x += moveCube; keys[VK_LEFT] = false; } if (keys[VK_UP]) //move cube along yAxis positive { globalPos.y += moveCube; keys[VK_DOWN] = false; } if (keys[VK_DOWN]) //move cube along yAxis negative { globalPos.y -= moveCube; keys[VK_UP] = false; } if (FORWARD) //W - move cube along zAxis positive { globalPos.z += moveCube; BACKWARD = false; } if (BACKWARD) //S- move cube along zAxis negative { globalPos.z -= moveCube; FORWARD = false; } if (ROT_LEFT) //rotate cube left { rotX +=0.01f; ROT_LEFT = false; } if (ROT_RIGHT) //rotate cube right { rotX -=0.01f; ROT_RIGHT = false; } I render the cube using this function which handles the shader and position on screen: void renderMovingCube(){ glUseProgram(myShader.handle()); GLuint matrixLoc4MovingCube = glGetUniformLocation(myShader.handle(), "ProjectionMatrix"); glUniformMatrix4fv(matrixLoc4MovingCube, 1, GL_FALSE, &ProjectionMatrix[0][0]); glm::mat4 viewMatrixMovingCube; viewMatrixMovingCube = glm::lookAt(camOrigin,camLookingAt,camNormalXYZ); ModelViewMatrix = glm::translate(viewMatrixMovingCube,globalPos); ModelViewMatrix = glm::rotate(ModelViewMatrix,rotX, glm::vec3(0,1,0)); //manually rotate glUniformMatrix4fv(glGetUniformLocation(myShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); movingCube.render(); glUseProgram(0); } The glm::lookAt function always points to the screens centre (0,0,0). The globalPos is a glm::vec3 globalPos(0,0,0); so when the program executes, renders the cube in the centre of the screens viewing matrix; the keyboard inputs above adjust the globalPos of the moving cube. The glm::rotate is the function used to rotate manually. My question is, how can I make the cube go forwards depending on what direction the cube is facing.... ie, once I've rotated the cube a few degrees using glm, the forwards direction, relative to the cube, is no longer on the z-Axis... how can I store the forwards direction and then use that to navigate forwards no matter what way it is facing? (either using vectors that can be applied to my code or some handy maths). Thanks.

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• Understanding clojure keywords

  - by tjb1982

  I'm taking my first steps with Clojure. Otherwise, I'm somewhat competent with JavaScript, Python, Java, and a little C. I was reading this artical that describes destructuring vectors and maps. E.g. => (def point [0 0]) => (let [[x y] point] => (println "the coordinates are:" x y)) the coordinates are: 0 0 but I'm having a difficult time understanding keywords. At first glance, they seem really simple, as they just evaluate to themselves: => :test :test But they seem to be used is so many different ways and I don't understand how to think about them. E.g., you can also do stuff like this: => (defn full-name [& {first :first last :last}] => (println first last)) => (full-name :first "Tom" :last "Brennan") Tom Brennan nil This doesn't seem intuitive to me. I would have guessed the arguments should have been something more like: (full-name {:first "Tom" :last "Brennan"}) because it looks like in the function definition that you're saying "no required arguments, but a variable number of arguments comes in the form of a single map". But it seems more like you're saying "no required arguments, but a variable number of arguments comes which should be a list of alternating keywords and values... ?" I'm not really sure how to wrap my brain around this. Also, things like this confuse me too: => (def population {:humans 5 :zombies 1000}) => (:zombies population) 1000 => (population :zombies) 1000 How do maps and keywords suddenly become functions? If I could get some clarification on the use of keywords in these two examples, that would be really helpful. Update I've also seen http://stackoverflow.com/questions/3337888/clojure-named-arguments and while the accepted answer is a great demonstration of how to use keywords with destructuring and named arguments, I'm really looking more for understanding how to think about them--why the language is designed this way and how I can best internalize their use.

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• Check if an object is facing another based on angles

  - by Isaiah

  I already have something that calculates the bearing angle to get one object to face another. You give it the positions and it returns the angle to get one to face the other. Now I need to figure out how tell if on object is facing toward another object within a specified field and I can't find any information about how to do this. The objects are obj1 and obj2. Their angles are at obj1.angle and obj2.angle. Their vectors are at obj1.pos and obj2.pos. It's in the format [x,y]. The angle to have one face directly at another is found with direction(obj1.pos,obj2.pos). I want to set the function up like this: isfacing(obj1,obj2,area){...} and return true/false depending if it's in the specified field area to the angle to directly see it. I've got a base like this: var isfacing = function (obj1,obj2,area){ var toface = direction(obj1.pos,obj2.pos); if(toface+area >= obj1.angle && ob1.angle >= toface-area){ return true; } return false; } But my problem is that the angles are in 360 degrees, never above 360 and never below 0. How can I account for that in this? If the first object's angle is say at 0 and say I subtract a field area of 20 or so. It'll check if it's less than -20! If I fix the -20 it becomes 340 but x < 340 isn't what I want, I'd have to x 340 in that case. Is there someone out there with more sleep than I that can help a new dev pulling an all-nighter just to get enemies to know if they're attacking in the right direction? I hope I'm making this harder than it seems. I'd just make them always face the main char if the producer didn't want attacks from behind to work while blocking. In which case I'll need the function above anyways. I've tried to give as much info as I can think would help. Also this is in 2d.

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• ConsumeStructuredBuffer, what am I doing wrong?

  - by John

  I'm trying to implement the 3rd exercise in chapter 12 of Introduction to 3D Game Programming with DirectX 11, that is: Implement a Compute Shader to calculate the length of 64 vectors. Previous exercises ask you to do the same with typed buffers and regular structured buffers and I had no problems with them. For what I've read, [Consume|Append]StructuredBuffers are bound to the pipeline using UnorderedAccessViews (as long as they use the D3D11_BUFFER_UAV_FLAG_APPEND, and the buffers have both D3D11_BIND_SHADER_RESOURCE and D3D11_BIND_UNORDERED_ACCESS bind flags). Problem is: my AppendStructuredBuffer works, since I can append data to it and retrieve it from the application to write to a results file, but the ConsumeStructuredBuffer always returns zeroed data. Data is in the buffer, since if I change the UAV to a ShaderResourceView and to a StructuredBuffer in the HLSL side it works. I don't know what I am missing: Should I initialize the ConsumeStructuredBuffer on the GPU, or can I do it when I create the buffer (as I amb currently doing). Is it OK to bind the buffer with a UAV as described above? Do I need to bind it as a ShaderResourceView somehow? Maybe I am missing some step? This is the declaration of buffers in the Compute Shader: struct Data { float3 v; }; struct Result { float l; }; ConsumeStructuredBuffer<Data> gInput; AppendStructuredBuffer<Result> gOutput; And here the creation of the buffer and UAV for input data: D3D11_BUFFER_DESC inputDesc; inputDesc.Usage = D3D11_USAGE_DEFAULT; inputDesc.ByteWidth = sizeof(Data) * mNumElements; inputDesc.BindFlags = D3D11_BIND_SHADER_RESOURCE | D3D11_BIND_UNORDERED_ACCESS; inputDesc.CPUAccessFlags = 0; inputDesc.StructureByteStride = sizeof(Data); inputDesc.MiscFlags = D3D11_RESOURCE_MISC_BUFFER_STRUCTURED; D3D11_SUBRESOURCE_DATA vinitData; vinitData.pSysMem = &data[0]; HR(md3dDevice->CreateBuffer(&inputDesc, &vinitData, &mInputBuffer)); D3D11_UNORDERED_ACCESS_VIEW_DESC uavDesc; uavDesc.Format = DXGI_FORMAT_UNKNOWN; uavDesc.ViewDimension = D3D11_UAV_DIMENSION_BUFFER; uavDesc.Buffer.FirstElement = 0; uavDesc.Buffer.Flags = D3D11_BUFFER_UAV_FLAG_APPEND; uavDesc.Buffer.NumElements = mNumElements; md3dDevice->CreateUnorderedAccessView(mInputBuffer, &uavDesc, &mInputUAV); Initial data is an array of Data structs, which contain a XMFLOAT3 with random data. I bind the UAV to the shader using the Effects framework: ID3DX11EffectUnorderedAccessViewVariable* Input = mFX->GetVariableByName("gInput")->AsUnorderedAccessView(); Input->SetUnorderedAccessView(uav); // uav is mInputUAV Any ideas? Thank you.

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• Ray Intersecting Plane Formula in C++/DirectX

  - by user4585

  I'm developing a picking system that will use rays that intersect volumes and I'm having trouble with ray intersection versus a plane. I was able to figure out spheres fairly easily, but planes are giving me trouble. I've tried to understand various sources and get hung up on some of the variables used within their explanations. Here is a snippet of my code: bool Picking() { D3DXVECTOR3 vec; D3DXVECTOR3 vRayDir; D3DXVECTOR3 vRayOrig; D3DXVECTOR3 vROO, vROD; // vect ray obj orig, vec ray obj dir D3DXMATRIX m; D3DXMATRIX mInverse; D3DXMATRIX worldMat; // Obtain project matrix D3DXMATRIX pMatProj = CDirectXRenderer::GetInstance()->Director()->Proj(); // Obtain mouse position D3DXVECTOR3 pos = CGUIManager::GetInstance()->GUIObjectList.front().pos; // Get window width & height float w = CDirectXRenderer::GetInstance()->GetWidth(); float h = CDirectXRenderer::GetInstance()->GetHeight(); // Transform vector from screen to 3D space vec.x = (((2.0f * pos.x) / w) - 1.0f) / pMatProj._11; vec.y = -(((2.0f * pos.y) / h) - 1.0f) / pMatProj._22; vec.z = 1.0f; // Create a view inverse matrix D3DXMatrixInverse(&m, NULL, &CDirectXRenderer::GetInstance()->Director()->View()); // Determine our ray's direction vRayDir.x = vec.x * m._11 + vec.y * m._21 + vec.z * m._31; vRayDir.y = vec.x * m._12 + vec.y * m._22 + vec.z * m._32; vRayDir.z = vec.x * m._13 + vec.y * m._23 + vec.z * m._33; // Determine our ray's origin vRayOrig.x = m._41; vRayOrig.y = m._42; vRayOrig.z = m._43; D3DXMatrixIdentity(&worldMat); //worldMat = aliveActors[0]->GetTrans(); D3DXMatrixInverse(&mInverse, NULL, &worldMat); D3DXVec3TransformCoord(&vROO, &vRayOrig, &mInverse); D3DXVec3TransformNormal(&vROD, &vRayDir, &mInverse); D3DXVec3Normalize(&vROD, &vROD); When using this code I'm able to detect a ray intersection via a sphere, but I have questions when determining an intersection via a plane. First off should I be using my vRayOrig & vRayDir variables for the plane intersection tests or should I be using the new vectors that are created for use in object space? When looking at a site like this for example: http://www.tar.hu/gamealgorithms/ch22lev1sec2.html I'm curious as to what D is in the equation AX + BY + CZ + D = 0 and how does it factor in to determining a plane intersection? Any help will be appreciated, thanks.

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• Opengl-es picking object

  - by lacas

  I saw a lot of picking code opengl-es, but nothing worked. Can someone give me what am I missing? My code is (from tutorials/forums) Vec3 far = Camera.getPosition(); Vec3 near = Shared.opengl().getPickingRay(ev.getX(), ev.getY(), 0); Vec3 direction = far.sub(near); direction.normalize(); Log.e("direction", direction.x+" "+direction.y+" "+direction.z); Ray mouseRay = new Ray(near, direction); for (int n=0; n<ObjectFactory.objects.size(); n++) { if (ObjectFactory.objects.get(n)!=null) { IObject obj = ObjectFactory.objects.get(n); float discriminant, b; float radius=0.1f; b = -mouseRay.getOrigin().dot(mouseRay.getDirection()); discriminant = b * b - mouseRay.getOrigin().dot(mouseRay.getOrigin()) + radius*radius; discriminant = FloatMath.sqrt(discriminant); double x1 = b - discriminant; double x2 = b + discriminant; Log.e("asd", obj.getName() + " "+discriminant+" "+x1+" "+x2); } } my camera vectors: //cam Vec3 position =new Vec3(-obj.getPosX()+x, obj.getPosZ()-0.3f, obj.getPosY()+z); Vec3 direction =new Vec3(-obj.getPosX(), obj.getPosZ(), obj.getPosY()); Vec3 up =new Vec3(0.0f, -1.0f, 0.0f); Camera.set(position, direction, up); and my picking code: public Vec3 getPickingRay(float mouseX, float mouseY, float mouseZ) { int[] viewport = getViewport(); float[] modelview = getModelView(); float[] projection = getProjection(); float winX, winY; float[] position = new float[4]; winX = (float)mouseX; winY = (float)Shared.screen.width - (float)mouseY; GLU.gluUnProject(winX, winY, mouseZ, modelview, 0, projection, 0, viewport, 0, position, 0); return new Vec3(position[0], position[1], position[2]); } My camera moving all the time in 3d space. and my actors/modells moving too. my camera is following one actor/modell and the user can move the camera on a circle on this model. How can I change the above code to working?

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• Java word scramble game [closed]

  - by Dan

  I'm working on code for a word scramble game in Java. I know the code itself is full of bugs right now, but my main focus is getting a vector of strings broken into two separate vectors containing hints and words. The text file that the strings are taken from has a colon separating them. So here is what I have so far. public WordApp() { inputRow = new TextInputBox(); inputRow.setLocation(200,100); phrases = new Vector <String>(FileUtilities.getStrings()); v_hints = new Vector<String>(); v_words = new Vector<String>(); textBox = new TextBox(200,100); textBox.setLocation(200,200); textBox.setText(scrambled + "\n\n Time Left: \t" + seconds/10 + "\n Score: \t" + score); hintBox = new TextBox(200,200); hintBox.setLocation(300,400); hintBox.hide(); Iterator <String> categorize = phrases.iterator(); while(categorize.hasNext()) { int index = phrases.indexOf(":"); String element = categorize.next(); v_words.add(element.substring(0,index)); v_hints.add(element.substring(index +1)); phrases.remove(index); System.out.print(index); } The FileUtilities file was given to us by the pofessor, here it is. import java.util.*; import java.io.*; public class FileUtilities { private static final String FILE_NAME = "javawords.txt"; //------------------ getStrings ------------------------- // // returns a Vector of Strings // Each string is of the form: word:hint // where word contains no spaces. // The words and hints are read from FILE_NAME // // public static Vector<String> getStrings ( ) { Vector<String> words = new Vector<String>(); File file = new File( FILE_NAME ); Scanner scanFile; try { scanFile = new Scanner( file); } catch ( IOException e) { System.err.println( "LineInput Error: " + e.getMessage() ); return null; } while ( scanFile.hasNextLine() ) { // read the word and follow it by a colon String s = scanFile.nextLine().trim().toUpperCase() + ":"; if( s.length()>1 && scanFile.hasNextLine() ) { // append the hint and add to collection s+= scanFile.nextLine().trim(); words.add(s); } } // shuffle Collections.shuffle(words); return words; } }

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• Simple thruster like behaviour when rotating sprite

  - by ensamgud

  I'm prototyping some 2D game concepts with XNA and have added some basic keyboard inputs to control a triangle sprite. When I press key up the sprite accelerates in it's current facing direction, when I release the key it brakes down. For rotation, when I press left/right keys I rotate the sprite. Currently the sprite immedately changes direction when I rotate it. What I want is for it to keep moving in the same direction when I rotate, until I hit key up, adding thrust in whatever direction the sprite is pointing at. This would simulate thrusters on a classic space shooter like Asteroids. I'm adding an image to describe the behaviour I'm after and some code samples of how I'm doing things at the moment. This is my player struct, holding information of the sprite. public struct PlayerData { public Vector2 Position; // where to draw the sprite public Vector2 Direction; // travel direction of sprite public float Angle; // rotation of sprite public float Velocity; public float Acceleration; public float Decelleration; public float RotationAcceleration; public float RotationDecceleration; public float TopSpeed; public float Scale; } This is how I'm currently handling thrusting / braking (when pressing/releasing key up) (simplified, removed some bounds checking etc): player.Velocity += player.Acceleration * 0.1f; player.Velocity -= player.Acceleration * 0.1f; And when I rotate the sprite left and right: player.Angle -= player.RotationAcceleration * 0.1f; player.Angle += player.RotationAcceleration * 0.1f; This runs in the update loop, keeps the direction updated and updates the position: Vector2 up = new Vector2(0f, -1f); Matrix rotMatrix = Matrix.CreateRotationZ(player.Angle); player.Direction = Vector2.Transform(up, rotMatrix); player.Direction *= player.Velocity; player.Position += player.Direction; I am following along various beginner tutorials and haven't found any describing this, but I have tried some on my own without success. Do I need to change my velocity and acceleration fields to Vectors instead of floats to accomplish this type of movement? I realise my Angle and the Direction vector is currently tied together and I need to disconnect these somehow to be able to rotate freely without changing the direction of the movement, but I can't quite figure out how to do this while keeping the acceleration/decceleration functional. Would appreciate an explanation rather than pure code samples. Thanks,

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• Complete Beginner to Game Programming and Unreal Engine 4, Looking For Advice [on hold]

  - by onemic

  I am currently a 2nd year programming student(Just finished my first year so I will be starting my second year in September) and have mainly learned C and C++ in my classes. In terms of what I know of C++, I know about general inheritance, polymorphism, overloading operators, iterators, a little bit about templates(only class and function templates) etc. but not of the more advanced topics like linked lists and other sequential containers(containers in general I guess), enumerations, most of the standard library(other than like strings and vectors), and probably a bunch of other stuff I dont even know about yet. I subscribed to Unreal Engine 4 as I was very intrigued by their Unreal Tournament announcement earlier this month, especially after hearing that UE4 is going completely C++. Of course my end goal in doing this programming program is to eventually go into game/graphics programming. Since it's my summer off, I thought what better way then to actually apply some of my skills to a personal project so I actually have a firmer understanding of C++ past what my professors tell me. My questions are this: What would be the best way to start off making a small personal game in UE4 as a project for the summer? What should I be aiming for, especially for someone that is still learning C++? Should I focus on making a simple 2D game rather than a 3D one to get started? Seeing the Flappy Chicken showcase intrigued me because before I thought the UE engine was pretty much pigeonholed into being for FPS games What should my expectations be going into UE4 and a game engine for the first time?(UE4 will be my first foray into making a game) What can I expect to gain from making things in UE4, in terms of making games and in terms of further fleshing out my knowledge of C++? Would you recommend I start off 100% using C++ for scripting or using the visual blueprints? Since I'm not a designer, how would I be able to add objects and designs to my game? For someone at my level is retaining the UE4 subscription worth it or is it better to cancel and resub when I learn enough about UE4 and C++? Lastly is there anything to be gained in terms of knowledge/insight through me looking at the source code for UE4? I opened it in VS2013, but noticed that most of the files were C# files and not cpp's. Thanks in advance for taking the time to answer.

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• What is going on in this SAT/vector projection code?

  - by ssb

  I'm looking at the example XNA SAT collision code presented here: http://www.xnadevelopment.com/tutorials/rotatedrectanglecollisions/rotatedrectanglecollisions.shtml See the following code: private int GenerateScalar(Vector2 theRectangleCorner, Vector2 theAxis) { //Using the formula for Vector projection. Take the corner being passed in //and project it onto the given Axis float aNumerator = (theRectangleCorner.X * theAxis.X) + (theRectangleCorner.Y * theAxis.Y); float aDenominator = (theAxis.X * theAxis.X) + (theAxis.Y * theAxis.Y); float aDivisionResult = aNumerator / aDenominator; Vector2 aCornerProjected = new Vector2(aDivisionResult * theAxis.X, aDivisionResult * theAxis.Y); //Now that we have our projected Vector, calculate a scalar of that projection //that can be used to more easily do comparisons float aScalar = (theAxis.X * aCornerProjected.X) + (theAxis.Y * aCornerProjected.Y); return (int)aScalar; } I think the problems I'm having with this come mostly from translating physics concepts into data structures. For example, earlier in the code there is a calculation of the axes to be used, and these are stored as Vector2, and they are found by subtracting one point from another, however these points are also stored as Vector2s. So are the axes being stored as slopes in a single Vector2? Next, what exactly does the Vector2 produced by the vector projection code represent? That is, I know it represents the projected vector, but as it pertains to a Vector2, what does this represent? A point on a line? Finally, what does the scalar at the end actually represent? It's fine to tell me that you're getting a scalar value of the projected vector, but none of the information I can find online seems to tell me about a scalar of a vector as it's used in this context. I don't see angles or magnitudes with these vectors so I'm a little disoriented when it comes to thinking in terms of physics. If this final scalar calculation is just a dot product, how is that directly applicable to SAT from here on? Is this what I use to calculate maximum/minimum values for overlap? I guess I'm just having trouble figuring out exactly what the dot product is representing in this particular context. Clearly I'm not quite up to date on my elementary physics, but any explanations would be greatly appreciated.

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• Glm Vector Transformations [duplicate]

  - by Reanimation

  This question already has an answer here: Car-like Physics - Basic Maths to Simulate Steering 2 answers I have a cube rendered on the screen which represents a car (or similar). Using Projection/Model matrices and Glm I am able to move it back and fourth along the axes and rotate it left or right. I'm having trouble with the vector mathematics to make the cube move forwards no matter which direction it's current orientation is. (ie. if I would like, if it's rotated right 30degrees, when it's move forwards, it travels along the 30degree angle on a new axes). I hope I've explained that correctly. This is what I've managed to do so far in terms of using glm to move the cube: glm::vec3 vel; //velocity vector void renderMovingCube(){ glUseProgram(movingCubeShader.handle()); GLuint matrixLoc4MovingCube = glGetUniformLocation(movingCubeShader.handle(), "ProjectionMatrix"); glUniformMatrix4fv(matrixLoc4MovingCube, 1, GL_FALSE, &ProjectionMatrix[0][0]); glm::mat4 viewMatrixMovingCube; viewMatrixMovingCube = glm::lookAt(camOrigin, camLookingAt, camNormalXYZ); vel.x = cos(rotX); vel.y=sin(rotX); vel*=moveCube; //move cube ModelViewMatrix = glm::translate(viewMatrixMovingCube,globalPos*vel); //bring ground and cube to bottom of screen ModelViewMatrix = glm::translate(ModelViewMatrix, glm::vec3(0,-48,0)); ModelViewMatrix = glm::rotate(ModelViewMatrix, rotX, glm::vec3(0,1,0)); //manually turn glUniformMatrix4fv(glGetUniformLocation(movingCubeShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader movingCube.render(); //draw glUseProgram(0); } keyboard input: void keyboard() { char BACKWARD = keys['S']; char FORWARD = keys['W']; char ROT_LEFT = keys['A']; char ROT_RIGHT = keys['D']; if (FORWARD) //W - move forwards { globalPos += vel; //globalPos.z -= moveCube; BACKWARD = false; } if (BACKWARD)//S - move backwards { globalPos.z += moveCube; FORWARD = false; } if (ROT_LEFT)//A - turn left { rotX +=0.01f; ROT_LEFT = false; } if (ROT_RIGHT)//D - turn right { rotX -=0.01f; ROT_RIGHT = false; } Where am I going wrong with my vectors? I would like change the direction of the cube (which it does) but then move forwards in that direction.

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• Recommendation for Document Management Solution

  - by BillN

  We've just been informed by our software vendor that the custom document management system they'd written is no longer in development, and will not be supported in the future. So we are looking at new document management systems. Requirements: Multiple input vectors, we receive documents via e-mail, fax, scanning, and from the originating application Ability to Redact or obscure data. Customers may fax an order with CC data, we want to attach the image of the order form with the order record, but the CC data needs to be protected. Same with Tax IDs. Certain users should be able to see the redacted data, but access should be logged. Version control on documents. We'd like Product Development and Marketing to be able to track various versions of documents like Packaging Designs, but ensure that users have the latest approved version. AD integration, my users don't need another password. Ability to integrate to other apps. Our current system, offers function keys in the order-entry system, that will spawn the viewer application, and open the correct document. Mass import facility, we have a half a terabyte of existing documents in the old system that we would like to import. Retention Policy. I'd like a way to have the system comply with the corporate retention policy, so that when a document of a certain type reaches a certain age, it gets deleted, or atleast marked for manual deletion. We are a Windows Server and HP-UX shop. Does anybody have any experience with Document Management systems that they would like to share? Thanks.

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• Encryption is hard: AES encryption to Hex

  - by Rob Cameron

  So, I've got an app at work that encrypts a string using ColdFusion. ColdFusion's bulit-in encryption helpers make it pretty simple: encrypt('string_to_encrypt','key','AES','HEX') What I'm trying to do is use Ruby to create the same encrypted string as this ColdFusion script is creating. Unfortunately encryption is the most confusing computer science subject known to man. I found a couple helper methods that use the openssl library and give you a really simple encryption/decryption method. Here's the resulting string: "\370\354D\020\357A\227\377\261G\333\314\204\361\277\250" Which looks unicode-ish to me. I've tried several libraries to convert this to hex but they all say it contains invalid characters. Trying to unpack it results in this: string = "\370\354D\020\357A\227\377\261G\333\314\204\361\277\250" string.unpack('U') ArgumentError: malformed UTF-8 character from (irb):19:in `unpack' from (irb):19 At the end of the day it's supposed to look like this (the output of the ColdFusion encrypt method): F8E91A689565ED24541D2A0109F201EF Of course that's assuming that all the padding, initialization vectors, salts, cypher types and a million other possible differences all line up. Here's the simple script I'm using to encrypt/decrypt: def aes(m,k,t) (aes = OpenSSL::Cipher::Cipher.new('aes-256-cbc').send(m)).key = Digest::SHA256.digest(k) aes.update(t) << aes.final end def encrypt(key, text) aes(:encrypt, key, text) end def decrypt(key, text) aes(:decrypt, key, text) end Any help? Maybe just a simple option I can pass to OpenSSL::Cipher::Cipher that will tell it to hex-encode the final string?

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• glm matrix conversion for DirectX

  - by niktehpui

  For on of the coursework specification I need to work with DirectX, so I tried to implement a DirectX Renderer in my small cross-platform framework (to have it optionally available for Windows). Since I want to stick to my dependencies I want use glm for vector/matrix/quaternions math. The vectors seem to be fully compatible with DirectX, but the glm::mat4 is not working properly in DirectX Effects Framework. I assumed the reason is that DirectX uses row majors layouts and OpenGL column majors (although if I remember right internally in HLSL DX uses column major as well), so I transposed the matrix, but I still get no proper results compared to using XNA-Math. XNA-Version of the code (works): XMMATRIX world = XMMatrixIdentity(); XMMATRIX view = XMMatrixLookAtLH(XMVectorSet(5.0, 5.0, 5.0, 1.0f), XMVectorZero(), XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f)); XMMATRIX proj = XMMatrixPerspectiveFovLH(0.25f*3.14f, 1.25f, 1.0f, 1000.0f); XMMATRIX worldViewProj = world*view*proj; m_fxWorldViewProj->SetMatrix(reinterpret_cast<float*>(&worldViewProj)); This works flawlessly and displays the expected colored cube. GLM-Version (does not work): glm::mat4 world(1.0f); glm::mat4 view = glm::lookAt(glm::vec3(5.0f, 5.0f, 5.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f)); glm::mat4 proj = glm::perspective(0.25f*3.14f, 1.25f, 1.0f, 1000.0f); glm::mat4 worldViewProj = glm::transpose(world*view*proj); m_fxWorldViewProj->SetMatrix(glm::value_ptr(worldViewProj)); Displays nothing, screen stays black. I really would like to stick to glm on all platforms.

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• Context migration in CUDA.NET

  - by Vyacheslav

  I'm currently using CUDA.NET library by GASS. I need to initialize cuda arrays (actually cublas vectors, but it doesn't matters) in one CPU thread and use them in other CPU thread. But CUDA context which holding all initialized arrays and loaded functions, can be attached to only one CPU thread. There is mechanism called context migration API to detach context from one thread and attach it to another. But i don't how to properly use it in CUDA.NET. I tried something like this: class Program { private static float[] vector1, vector2; private static CUDA cuda; private static CUBLAS cublas; private static CUdeviceptr ptr; static void Main(string[] args) { cuda = new CUDA(false); cublas = new CUBLAS(cuda); cuda.Init(); cuda.CreateContext(0); AllocateVectors(); cuda.DetachContext(); CUcontext context = cuda.PopCurrentContext(); GetVectorFromDeviceAsync(context); } private static void AllocateVectors() { vector1 = new float[]{1f, 2f, 3f, 4f, 5f}; ptr = cublas.Allocate(vector1.Length, sizeof (float)); cublas.SetVector(vector1, ptr); vector2 = new float[5]; } private static void GetVectorFromDevice(object objContext) { CUcontext localContext = (CUcontext) objContext; cuda.PushCurrentContext(localContext); cuda.AttachContext(localContext); //change vector somehow vector1[0] = -1; //copy changed vector to device cublas.SetVector(vector1, ptr); cublas.GetVector(ptr, vector2); CUDADriver.cuCtxPopCurrent(ref localContext); } private static void GetVectorFromDeviceAsync(CUcontext cUcontext) { Thread thread = new Thread(GetVectorFromDevice); thread.IsBackground = false; thread.Start(cUcontext); } } But execution fails on attempt to copy changed vector to device because context is not attached? Any ideas how i can get it work?

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• Handle URI hacking gracefully in ASP.NET

  - by asbjornu

  I've written an application that handles most exceptions gracefully, with the page's design intact and a pretty error message. My application catches them all in the Page_Error event and there adds the exception to HttpContext.Curent.Context.Items and then does a Server.Transfer to an Error.aspx page. I find this to be the only viable solution in ASP.NET as there seems to be no other way to do it in a centralized and generic manner. I also handle the Application_Error and there I do some inspection on the exception that occurred to find out if I can handle it gracefully or not. Exceptions I've found I can handle gracefully are such that are thrown after someone hacking the URI to contain characters the .NET framework considers dangerous or basically just illegal at the file system level. Such URIs can look like e.g.: http://exmample.com/"illegal" http://example.com/illegal"/ http://example.com/illegal / (notice the space before the slash at the end of the last URI). I'd like these URIs to respond with a "404 Not Found" and a friendly message as well as not causing any error report to be sent to avoid DDOS attack vectors and such. I have, however, not found an elegant way to catch these types of errors. What I do now is inspect the exception.TargetSite.Name property, and if it's equal to CheckInvalidPathChars, ValidatePath or CheckSuspiciousPhysicalPath, I consider it a "path validation exception" and respond with a 404. This seems like a hack, though. First, the list of method names is probably not complete in any way and second, there's the possibility that these method names gets replaced or renamed down the line which will cause my code to break. Does anyone have an idea how I can handle this less hard-coded and much more future-proof way? PS: I'm using System.Web.Routing in my application to have clean and sensible URIs, if that is of any importance to any given solution.

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• Need help with artificial neural network

  - by deckard cain

  I have an input data for neural network that consists of 2 vectors with 200 elements, that i got from some program for generating signals. So it is actually 2x200 input to my nnet. As target data, i have one 1x200 vector that i also got from the same program. That is my training data set. I gather as much of those sets as i want so i transfer them to matlab and save them as, for example, set1, set2,.... When i am creating neural net, using newfit function (backropagation algorithm and everyhting else is set by default because i am kind of unexperianced with neural nets so i will have to experiment) i'm creating it using set1 only for example. Then, when i am to train neural net i train it for set1 then load set2 and train for it and so on. so its like this function net = create_fit_net(inputs,targets) numHiddenNeurons = 20; net = newfit(inputs,targets,numHiddenNeurons); net=train(net,inputs,targets); load set2; net=train(net,inputs,targets); load set3; net=train(net,inputs,targets); load set4; net=train(net,inputs,targets); i am using 4 sets of data here and all sets have variables of same name and size. My quesion is, am i doing this the right way, because, when doing simulation in some other m file, i am getting bad results, and every time i get different results. Does it matter if i create network with one set and then train with others too, and does it matter what set do i use to train network 1st? Also, i am confused about the amount of neurons to use (im using in the example 20 but actually i tried 1, 10, 30, 50, 100 200 and even 300 and i get nothing). If you have any suggestions, i'd be glad to take them into consideration. Any help is welcome. thanks in advance

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• Disco/MapReduce: Using results of previous iteration as input to new iteration

  - by muckabout

  Currently am implementing PageRank on Disco. As an iterative algorithm, the results of one iteration are used as input to the next iteration. I have a large file which represents all the links, with each row representing a page and the values in the row representing the pages to which it links. For Disco, I break this file into N chunks, then run MapReduce for one round. As a result, I get a set of (page, rank) tuples. I'd like to feed this rank to the next iteration. However, now my mapper needs two inputs: the graph file, and the pageranks. I would like to "zip" together the graph file and the page ranks, such that each line represents a page, it's rank, and it's out links. Since this graph file is separated into N chunks, I need to split the pagerank vector into N parallel chunks, and zip the regions of the pagerank vectors to the graph chunks This all seems more complicated than necessary, and as a pretty straightforward operation (with the quintessential mapreduce algorithm), it seems I'm missing something about Disco that could really simplify the approach. Any thoughts?

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• How to avoid reallocation using the STL (C++)

  - by Tue Christensen

  This question is derived of the topic: http://stackoverflow.com/questions/2280655/vector-reserve-c I am using a datastructur of the type vector<vector<vector<double> > >. It is not possible to know the size of each of these vector (except the outer one) before items (doubles) are added. I can get an approximate size (upper bound) on the number of items in each "dimension". A solution with the shared pointers might be the way to go, but I would like to try a solution where the vector<vector<vector<double> > > simply has .reserve()'ed enough space (or in some other way has allocated enough memory). Will A.reserve(500) (assumming 500 is the size or, alternatively an upper bound on the size) be enough to hold "2D" vectors of large size, say [1000][10000]? The reason for my question is mainly because I cannot see any way of reasonably estimating the size of the interior of A at the time of .reserve(500). An example of my question: vector A; A.reserve(500+1); vector temp2; vector temp1 (666,666); for(int i=0;i<500;i++) { A.push_back(temp2); for(int j=0; j< 10000;j++) { A.back().push_back(temp1); } } Will this ensure that no reallocation is done for A? If temp2.reserve(100000) and temp1.reserve(1000) where added at creation will this ensure no reallocation at all will occur at all? In the above please disregard the fact that memory could be wasted due to conservative .reserve() calls. Thank you all in advance!

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• simple Stata program

  - by Cyrus S

  I am trying to write a simple program to combine coefficient and standard error estimates from a set of regression fits. I run, say, 5 regressions, and store the coefficient(s) and standard error(s) of interest into vectors (Stata matrix objects, actually). Then, I need to do the following: Find the mean value of the coefficient estimates. Combine the standard error estimates according to the formula suggested for combining results from "multiple imputation". The formula is the square root of the formula for "T" on page 6 of the following document: http://bit.ly/b05WX3 I have written Stata code that does this once, but I want to write this as a function (or "program", in Stata speak) that takes as arguments the vector (or matrix, if possible, to combine multiple estimates at once) of regression coefficient estimates and the vector (or matrix) of corresponding standard error estimates, and then generates 1 and 2 above. Here is the code that I wrote: (breg is a 1x5 vector of the regression coefficient estimates, and sereg is a 1x5 vector of the associated standard error estimates) mat ones = (1,1,1,1,1) mat bregmean = (1/5)*(ones*breg’) scalar bregmean_s = bregmean[1,1] mat seregmean = (1/5)*(ones*sereg’) mat seregbtv = (1/4)*(breg - bregmean#ones)* (breg - bregmean#ones)’ mat varregmi = (1/5)*(sereg*sereg’) + (1+(1/5))* seregbtv scalar varregmi_s = varregmi[1,1] scalar seregmi = sqrt(varregmi_s) disp bregmean_s disp seregmi This gives the right answer for a single instance. Any pointers would be great! UPDATE: I completed the code for combining estimates in a kXm matrix of coefficients/parameters (k is the number of parameters, m the number of imputations). Code can be found here: http://bit.ly/cXJRw1 Thanks to Tristan and Gabi for the pointers.

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• PostgreSQL: Full Text Search - How to search partial words ?

  - by Anthoni Gardner

  Hello, Following a question posted here about how I can increase the speed on one of my SQL Search methods, I was advised to update my table to make use of Full Text Search. This is what I have now done, using Gist indexes to make searching faster. On some of the "plain" queries I have noticed a marked increase which I am very happy about. However, I am having difficulty in searching for partial words. For example I have several records that contain the word Squire (454) and I have several records that contain Squirrel (173). Now if I search for Squire it only returns the 454 records but I also want it to return the Squirrel records as well. My query looks like this SELECT title FROM movies WHERE vectors @@ to_tsoquery('squire'); I thought I could do to_tsquery('squire%') but that does not work. How do I get it to search for partial matches ? Also, in my database I have records that are movies and others that are just TV Shows. These are differentiated by the "" over the name, so like "Munsters" is a TV Show, whereas The Munsters is the film of the show. What I want to be able to do is search for just the TV Show AND just the movies. Any idea on how I can achieve this ? Regards Anthoni

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• Fitting Gaussian KDE in numpy/scipy in Python

  - by user248237

  I am fitting a Gaussian kernel density estimator to a variable that is the difference of two vectors, called "diff", as follows: gaussian_kde_covfact(diff, smoothing_param) -- where gaussian_kde_covfact is defined as: class gaussian_kde_covfact(stats.gaussian_kde): def __init__(self, dataset, covfact = 'scotts'): self.covfact = covfact scipy.stats.gaussian_kde.__init__(self, dataset) def _compute_covariance_(self): '''not used''' self.inv_cov = np.linalg.inv(self.covariance) self._norm_factor = sqrt(np.linalg.det(2*np.pi*self.covariance)) * self.n def covariance_factor(self): if self.covfact in ['sc', 'scotts']: return self.scotts_factor() if self.covfact in ['si', 'silverman']: return self.silverman_factor() elif self.covfact: return float(self.covfact) else: raise ValueError, \ 'covariance factor has to be scotts, silverman or a number' def reset_covfact(self, covfact): self.covfact = covfact self.covariance_factor() self._compute_covariance() This works, but there is an edge case where the diff is a vector of all 0s. In that case, I get the error: File "/srv/pkg/python/python-packages/python26/scipy/scipy-0.7.1/lib/python2.6/site-packages/scipy/stats/kde.py", line 334, in _compute_covariance self.inv_cov = linalg.inv(self.covariance) File "/srv/pkg/python/python-packages/python26/scipy/scipy-0.7.1/lib/python2.6/site-packages/scipy/linalg/basic.py", line 382, in inv if info>0: raise LinAlgError, "singular matrix" numpy.linalg.linalg.LinAlgError: singular matrix What's a way to get around this? In this case, I'd like it to return a density that's essentially peaked completely at a difference of 0, with no mass everywhere else. thanks.

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• WPF 3D extrude "a bitmap"

  - by Bgnt44

  Hi, I'm looking for a way to simulate a projector in wpf 3D : i've these "in" parameters : beam shape : a black and white bitmap file beam size ( ex : 30 °) beam color beam intensity ( dimmer ) projector position (x,y,z) beam position (pan(x),tilt(y) relative to projector) First i was thinking of using light object but it seem that wpf can't do that So, now i think that i can make for each projector a polygon from my bitmap... First i need to convert the black and white bitmap to vector. Only Simple shape ( bubble, line,dot,cross ...) Is there any WPF way to do that ? Or maybe a external program file (freeware); then i need to build the polygon, with the shape of the converted bitmap , color , size , orientation in parameter. i don't know how can i defined the lenght of the beam , and if it can be infiny ... To show the beam result, i think of making a room ( floor , wall ...) and beam will end to these wall... i don't care of real light render ( dispersion ...) but the scene render has to be real time and at least 15 times / second (with probably from one to 100 projectors at the same time), information about position, angle,shape,color will be sent for each render... Well so, i need sample for that, i guess that all of these things could be useful for other people If you have sample code : Convert Bitmap to vector Extrude vectors from one point with a angle parameter until collision of a wall Set x,y position of the beam depend of the projector position Set Alpha intensity of the beam, color Maybe i'm totally wrong and WPF is not ready for that , so advise me about other way ( xna,d3D ) with sample of course ;-) Thanks you

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• Python: fetching SVG file using urllib is returning binary when I need ASCII

  - by Drew Dara-Abrams

  I'm using urllib (in Python) to fetch an SVG file: import urllib urllib.urlopen('http://alpha.vectors.cloudmade.com/BC9A493B41014CAABB98F0471D759707/-122.2487,37.87588,-122.265823,37.868054?styleid=1&viewport=400x231').read() which produces output of the sort: xb6\xf6\x00\xb3\xfb2\xff\xda\xc5\xf2\xc2\x14\xef\xcd\x82\x0b\xdbU\xb0\x81\xcaF\xd8\x1a\xf6\xdf[i)\xba\xcf\x80\xab\xd6\x8c\xe3l_\xe7\n\xed2,\xbdm\xa0_|\xbb\x12\xff\xb6\xf8\xda\xd9\xc3\xd9\t\xde\x9a\xf8\xae\xb3T\xa3\r`\x8a\x08!T\xfb8\x92\x95\x0c\xdd\x8b!\x02P\xea@\x98\x1c^\xc7\xda\\\xec\xe3\xe1\xbe,0\xcd\xbeZ~\x92\xb3\xfa\xdd\xfcbyu\xb8\x83\xbb\xbdS\x0f\x82\x0b\xfe\xf5_\xdawn\xff\xef_\xff\xe5\xfa\x1f?\xbf\xffoZ\x0f\x8b\xbfV\xf4\x04\x00' when I was expecting more like this: <?xml version='1.0' encoding='UTF-8'?> <svg xmlns="http://www.w3.org/2000/svg" xmlns:cm="http://cloudmade.com/" width="400" height="231"> <rect width="100%" height="100%" fill="#eae8dd" opacity="1"/> <g transform="scale(0.209849975856)"> <g transform="translate(13610569, 4561906)" flood-opacity="0.1" flood-color="grey"> <path d="M -13610027.720000000670552 -4562403.660000000149012 I guess this is an issue of binary vs. ASCII. Can anyone help me (a Python newbie) with the appropriate conversion so that I can get on with parsing and manipulating the SVG code?

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