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  • Prim's MST algorithm implementation with Java

    - by user1290164
    I'm trying to write a program that'll find the MST of a given undirected weighted graph with Kruskal's and Prim's algorithms. I've successfully implemented Kruskal's algorithm in the program, but I'm having trouble with Prim's. To be more precise, I can't figure out how to actually build the Prim function so that it'll iterate through all the vertices in the graph. I'm getting some IndexOutOfBoundsException errors during program execution. I'm not sure how much information is needed for others to get the idea of what I have done so far, but hopefully there won't be too much useless information. This is what I have so far: I have a Graph, Edge and a Vertex class. Vertex class mostly just an information storage that contains the name (number) of the vertex. Edge class can create a new Edge that has gets parameters (Vertex start, Vertex end, int edgeWeight). The class has methods to return the usual info like start vertex, end vertex and the weight. Graph class reads data from a text file and adds new Edges to an ArrayList. The text file also tells us how many vertecis the graph has, and that gets stored too. In the Graph class, I have a Prim() -method that's supposed to calculate the MST: public ArrayList<Edge> Prim(Graph G) { ArrayList<Edge> edges = G.graph; // Copies the ArrayList with all edges in it. ArrayList<Edge> MST = new ArrayList<Edge>(); Random rnd = new Random(); Vertex startingVertex = edges.get(rnd.nextInt(G.returnVertexCount())).returnStartingVertex(); // This is just to randomize the starting vertex. // This is supposed to be the main loop to find the MST, but this is probably horribly wrong.. while (MST.size() < returnVertexCount()) { Edge e = findClosestNeighbour(startingVertex); MST.add(e); visited.add(e.returnStartingVertex()); visited.add(e.returnEndingVertex()); edges.remove(e); } return MST; } The method findClosesNeighbour() looks like this: public Edge findClosestNeighbour(Vertex v) { ArrayList<Edge> neighbours = new ArrayList<Edge>(); ArrayList<Edge> edges = graph; for (int i = 0; i < edges.size() -1; ++i) { if (edges.get(i).endPoint() == s.returnVertexID() && !visited(edges.get(i).returnEndingVertex())) { neighbours.add(edges.get(i)); } } return neighbours.get(0); // This is the minimum weight edge in the list. } ArrayList<Vertex> visited and ArrayList<Edges> graph get constructed when creating a new graph. Visited() -method is simply a boolean check to see if ArrayList visited contains the Vertex we're thinking about moving to. I tested the findClosestNeighbour() independantly and it seemed to be working but if someone finds something wrong with it then that feedback is welcome also. Mainly though as I mentioned my problem is with actually building the main loop in the Prim() -method, and if there's any additional info needed I'm happy to provide it. Thank you. Edit: To clarify what my train of thought with the Prim() method is. What I want to do is first randomize the starting point in the graph. After that, I will find the closest neighbor to that starting point. Then we'll add the edge connecting those two points to the MST, and also add the vertices to the visited list for checking later, so that we won't form any loops in the graph. Here's the error that gets thrown: Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.rangeCheck(Unknown Source) at java.util.ArrayList.get(Unknown Source) at Graph.findClosestNeighbour(graph.java:203) at Graph.Prim(graph.java:179) at MST.main(MST.java:49) Line 203: return neighbour.get(0); in findClosestNeighbour() Line 179: Edge e = findClosestNeighbour(startingVertex); in Prim()

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  • OpenGL index buffer object with additional data

    - by muksie
    I have a large set of lines, which I render from a vertex buffer object using glMultiDrawArrays(GL_LINE_STRIP, ...); This works perfectly well. Now I have lots of vertex pairs which I also have to visualize. Every pair consists of two vertices on two different lines, and the distance between the vertices is small. However, I like to have the ability to draw a line between all vertex pairs with a distance less than a certain value. What I like to have is something like a buffer object with the following structure: i1, j1, r1, i2, j2, r2, i3, j3, r3, ... where the i's and j's are indices pointing to vertices and the r's are the distances between those vertices. Thus every vertex pair is stored as a (i, j, r) tuple. Then I like to have a (vertex) shader which only draws the vertex pairs with r < SOME_VALUE as a line. So my question is, what is the best way to achieve this?

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  • Graph Tour with Uniform Cost Search in Java

    - by user324817
    Hi. I'm new to this site, so hopefully you guys don't mind helping a nub. Anyway, I've been asked to write code to find the shortest cost of a graph tour on a particular graph, whose details are read in from file. The graph is shown below: http://img339.imageshack.us/img339/8907/graphr.jpg This is for an Artificial Intelligence class, so I'm expected to use a decent enough search method (brute force has been allowed, but not for full marks). I've been reading, and I think that what I'm looking for is an A* search with constant heuristic value, which I believe is a uniform cost search. I'm having trouble wrapping my head around how to apply this in Java. Basically, here's what I have: Vertex class - ArrayList<Edge> adjacencies; String name; int costToThis; Edge class - final Vertex target; public final int weight; Now at the moment, I'm struggling to work out how to apply the uniform cost notion to my desired goal path. Basically I have to start on a particular node, visit all other nodes, and end on that same node, with the lowest cost. As I understand it, I could use a PriorityQueue to store all of my travelled paths, but I can't wrap my head around how I show the goal state as the starting node with all other nodes visited. Here's what I have so far, which is pretty far off the mark: public static void visitNode(Vertex vertex) { ArrayList<Edge> firstEdges = vertex.getAdjacencies(); for(Edge e : firstEdges) { e.target.costToThis = e.weight + vertex.costToThis; queue.add(e.target); } Vertex next = queue.remove(); visitNode(next); } Initially this takes the starting node, then recursively visits the first node in the PriorityQueue (the path with the next lowest cost). My problem is basically, how do I stop my program from following a path specified in the queue if that path is at the goal state? The queue currently stores Vertex objects, but in my mind this isn't going to work as I can't store whether other vertices have been visited inside a Vertex object. Help is much appreciated! Josh

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  • Computation overhead in C# - Using getters/setters vs. modifying arrays directly and casting speeds

    - by Jeffrey Kern
    I was going to write a long-winded post, but I'll boil it down here: I'm trying to emulate the graphical old-school style of the NES via XNA. However, my FPS is SLOW, trying to modify 65K pixels per frame. If I just loop through all 65K pixels and set them to some arbitrary color, I get 64FPS. The code I made to look-up what colors should be placed where, I get 1FPS. I think it is because of my object-orented code. Right now, I have things divided into about six classes, with getters/setters. I'm guessing that I'm at least calling 360K getters per frame, which I think is a lot of overhead. Each class contains either/and-or 1D or 2D arrays containing custom enumerations, int, Color, or Vector2D, bytes. What if I combined all of the classes into just one, and accessed the contents of each array directly? The code would look a mess, and ditch the concepts of object-oriented coding, but the speed might be much faster. I'm also not concerned about access violations, as any attempts to get/set the data in the arrays will done in blocks. E.g., all writing to arrays will take place before any data is accessed from them. As for casting, I stated that I'm using custom enumerations, int, Color, and Vector2D, bytes. Which data types are fastest to use and access in the .net Framework, XNA, XBox, C#? I think that constant casting might be a cause of slowdown here. Also, instead of using math to figure out which indexes data should be placed in, I've used precomputed lookup tables so I don't have to use constant multiplication, addition, subtraction, division per frame. :)

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  • (Java) Is there a type of object that can handle anything from primitives to arrays?

    - by Michael
    I'm pretty new to Java, so I'm hoping one of you guys knows how to do this. I'm having the user specify both the type and value of arguments, in any XML-like way, to be passed to methods that are external to my application. Example: javac myAppsName externalJavaClass methodofExternalClass [parameters] Of course, to find the proper method, we have to have the proper parameter types as the method may be overloaded and that's the only way to tell the difference between the different versions. Parameters are currently formatted in this manner: (type)value(/type), e.g. (int)71(/int) (string)This is my string that I'm passing as a parameter!(/string) I parse them, getting the constructor for whatever type is indicated, then execute that constructor by running its method, newInstance(<String value>), loading the new instance into an Object. This works fine and dandy, but as we all know, some methods take arrays, or even multi-dimensional arrays. I could handle the argument formatting like so: (array)(array)(int)0(/int)(int)1(/int)(/array)(array)(int)2(/int)(int)3(/int)(/array)(/array)... or perhaps even better... {{(int)0(/int)(int)1(/int)}{(int)2(/int)(int)3(/int)}}. The question is, how can this be implemented? Do I have to start wrapping everything in an Object[] array so I can handle primitives, etc. as argObj[0], but load an array as I normally would? (Unfortunately, I would have to make it an Object[][] array if I wanted to support two-dimensional arrays. This implementation wouldn't be very pretty.)

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  • Why does setting a geometry shader cause my sprites to vanish?

    - by ChaosDev
    My application has multiple screens with different tasks. Once I set a geometry shader to the device context for my custom terrain, it works and I get the desired results. But then when I get back to the main menu, all sprites and text disappear. These sprites don't dissappear when I use pixel and vertex shaders. The sprites are being drawn through D3D11, of course, with specified view and projection matrices as well an input layout, vertex, and pixel shader. I'm trying DeviceContext->ClearState() but it does not help. Any ideas? void gGeometry::DrawIndexedWithCustomEffect(gVertexShader*vs,gPixelShader* ps,gGeometryShader* gs=nullptr) { unsigned int offset = 0; auto context = mp_D3D->mp_Context; //set topology context->IASetPrimitiveTopology(m_Topology); //set input layout context->IASetInputLayout(mp_inputLayout); //set vertex and index buffers context->IASetVertexBuffers(0,1,&mp_VertexBuffer->mp_Buffer,&m_VertexStride,&offset); context->IASetIndexBuffer(mp_IndexBuffer->mp_Buffer,mp_IndexBuffer->m_DXGIFormat,0); //send constant buffers to shaders context->VSSetConstantBuffers(0,vs->m_CBufferCount,vs->m_CRawBuffers.data()); context->PSSetConstantBuffers(0,ps->m_CBufferCount,ps->m_CRawBuffers.data()); if(gs!=nullptr) { context->GSSetConstantBuffers(0,gs->m_CBufferCount,gs->m_CRawBuffers.data()); context->GSSetShader(gs->mp_D3DGeomShader,0,0);//after this call all sprites disappear } //set shaders context->VSSetShader( vs->mp_D3DVertexShader, 0, 0 ); context->PSSetShader( ps->mp_D3DPixelShader, 0, 0 ); //draw context->DrawIndexed(m_indexCount,0,0); } //sprites void gSpriteDrawer::Draw(gTexture2D* texture,const RECT& dest,const RECT& source, const Matrix& spriteMatrix,const float& rotation,Vector2d& position,const Vector2d& origin,const Color& color) { VertexPositionColorTexture* verticesPtr; D3D11_MAPPED_SUBRESOURCE mappedResource; unsigned int TriangleVertexStride = sizeof(VertexPositionColorTexture); unsigned int offset = 0; float halfWidth = ( float )dest.right / 2.0f; float halfHeight = ( float )dest.bottom / 2.0f; float z = 0.1f; int w = texture->Width(); int h = texture->Height(); float tu = (float)source.right/(w); float tv = (float)source.bottom/(h); float hu = (float)source.left/(w); float hv = (float)source.top/(h); Vector2d t0 = Vector2d( hu+tu, hv); Vector2d t1 = Vector2d( hu+tu, hv+tv); Vector2d t2 = Vector2d( hu, hv+tv); Vector2d t3 = Vector2d( hu, hv+tv); Vector2d t4 = Vector2d( hu, hv); Vector2d t5 = Vector2d( hu+tu, hv); float ex=(dest.right/2)+(origin.x); float ey=(dest.bottom/2)+(origin.y); Vector4d v4Color = Vector4d(color.r,color.g,color.b,color.a); VertexPositionColorTexture vertices[] = { { Vector3d( dest.right-ex, -ey, z),v4Color, t0}, { Vector3d( dest.right-ex, dest.bottom-ey , z),v4Color, t1}, { Vector3d( -ex, dest.bottom-ey , z),v4Color, t2}, { Vector3d( -ex, dest.bottom-ey , z),v4Color, t3}, { Vector3d( -ex, -ey , z),v4Color, t4}, { Vector3d( dest.right-ex, -ey , z),v4Color, t5}, }; auto mp_context = mp_D3D->mp_Context; // Lock the vertex buffer so it can be written to. mp_context->Map(mp_vertexBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource); // Get a pointer to the data in the vertex buffer. verticesPtr = (VertexPositionColorTexture*)mappedResource.pData; // Copy the data into the vertex buffer. memcpy(verticesPtr, (void*)vertices, (sizeof(VertexPositionColorTexture) * 6)); // Unlock the vertex buffer. mp_context->Unmap(mp_vertexBuffer, 0); //set vertex shader mp_context->IASetVertexBuffers( 0, 1, &mp_vertexBuffer, &TriangleVertexStride, &offset); //set texture mp_context->PSSetShaderResources( 0, 1, &texture->mp_SRV); //set matrix to shader mp_context->UpdateSubresource(mp_matrixBuffer, 0, 0, &spriteMatrix, 0, 0 ); mp_context->VSSetConstantBuffers( 0, 1, &mp_matrixBuffer); //draw sprite mp_context->Draw( 6, 0 ); }

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  • problem with loading in .FBX meshes in DirectX 10

    - by N0xus
    I'm trying to load in meshes into DirectX 10. I've created a bunch of classes that handle it and allow me to call in a mesh with only a single line of code in my main game class. How ever, when I run the program this is what renders: In the debug output window the following errors keep appearing: D3D10: ERROR: ID3D10Device::DrawIndexed: Input Assembler - Vertex Shader linkage error: Signatures between stages are incompatible. The reason is that Semantic 'TEXCOORD' is defined for mismatched hardware registers between the output stage and input stage. [ EXECUTION ERROR #343: DEVICE_SHADER_LINKAGE_REGISTERINDEX ] D3D10: ERROR: ID3D10Device::DrawIndexed: Input Assembler - Vertex Shader linkage error: Signatures between stages are incompatible. The reason is that the input stage requires Semantic/Index (POSITION,0) as input, but it is not provided by the output stage. [ EXECUTION ERROR #342: DEVICE_SHADER_LINKAGE_SEMANTICNAME_NOT_FOUND ] The thing is, I've no idea how to fix this. The code I'm using does work and I've simply brought all of that code into a new project of mine. There are no build errors and this only appears when the game is running The .fx file is as follows: float4x4 matWorld; float4x4 matView; float4x4 matProjection; struct VS_INPUT { float4 Pos:POSITION; float2 TexCoord:TEXCOORD; }; struct PS_INPUT { float4 Pos:SV_POSITION; float2 TexCoord:TEXCOORD; }; Texture2D diffuseTexture; SamplerState diffuseSampler { Filter = MIN_MAG_MIP_POINT; AddressU = WRAP; AddressV = WRAP; }; // // Vertex Shader // PS_INPUT VS( VS_INPUT input ) { PS_INPUT output=(PS_INPUT)0; float4x4 viewProjection=mul(matView,matProjection); float4x4 worldViewProjection=mul(matWorld,viewProjection); output.Pos=mul(input.Pos,worldViewProjection); output.TexCoord=input.TexCoord; return output; } // // Pixel Shader // float4 PS(PS_INPUT input ) : SV_Target { return diffuseTexture.Sample(diffuseSampler,input.TexCoord); //return float4(1.0f,1.0f,1.0f,1.0f); } RasterizerState NoCulling { FILLMODE=SOLID; CULLMODE=NONE; }; technique10 Render { pass P0 { SetVertexShader( CompileShader( vs_4_0, VS() ) ); SetGeometryShader( NULL ); SetPixelShader( CompileShader( ps_4_0, PS() ) ); SetRasterizerState(NoCulling); } } In my game, the .fx file and model are called and set as follows: Loading in shader file //Set the shader flags - BMD DWORD dwShaderFlags = D3D10_SHADER_ENABLE_STRICTNESS; #if defined( DEBUG ) || defined( _DEBUG ) dwShaderFlags |= D3D10_SHADER_DEBUG; #endif ID3D10Blob * pErrorBuffer=NULL; if( FAILED( D3DX10CreateEffectFromFile( TEXT("TransformedTexture.fx" ), NULL, NULL, "fx_4_0", dwShaderFlags, 0, md3dDevice, NULL, NULL, &m_pEffect, &pErrorBuffer, NULL ) ) ) { char * pErrorStr = ( char* )pErrorBuffer->GetBufferPointer(); //If the creation of the Effect fails then a message box will be shown MessageBoxA( NULL, pErrorStr, "Error", MB_OK ); return false; } //Get the technique called Render from the effect, we need this for rendering later on m_pTechnique=m_pEffect->GetTechniqueByName("Render"); //Number of elements in the layout UINT numElements = TexturedLitVertex::layoutSize; //Get the Pass description, we need this to bind the vertex to the pipeline D3D10_PASS_DESC PassDesc; m_pTechnique->GetPassByIndex( 0 )->GetDesc( &PassDesc ); //Create Input layout to describe the incoming buffer to the input assembler if (FAILED(md3dDevice->CreateInputLayout( TexturedLitVertex::layout, numElements,PassDesc.pIAInputSignature, PassDesc.IAInputSignatureSize, &m_pVertexLayout ) ) ) { return false; } model loading: m_pTestRenderable=new CRenderable(); //m_pTestRenderable->create<TexturedVertex>(md3dDevice,8,6,vertices,indices); m_pModelLoader = new CModelLoader(); m_pTestRenderable = m_pModelLoader->loadModelFromFile( md3dDevice,"armoredrecon.fbx" ); m_pGameObjectTest = new CGameObject(); m_pGameObjectTest->setRenderable( m_pTestRenderable ); // Set primitive topology, how are we going to interpet the vertices in the vertex buffer md3dDevice->IASetPrimitiveTopology( D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST ); if ( FAILED( D3DX10CreateShaderResourceViewFromFile( md3dDevice, TEXT( "armoredrecon_diff.png" ), NULL, NULL, &m_pTextureShaderResource, NULL ) ) ) { MessageBox( NULL, TEXT( "Can't load Texture" ), TEXT( "Error" ), MB_OK ); return false; } m_pDiffuseTextureVariable = m_pEffect->GetVariableByName( "diffuseTexture" )->AsShaderResource(); m_pDiffuseTextureVariable->SetResource( m_pTextureShaderResource ); Finally, the draw function code: //All drawing will occur between the clear and present m_pViewMatrixVariable->SetMatrix( ( float* )m_matView ); m_pWorldMatrixVariable->SetMatrix( ( float* )m_pGameObjectTest->getWorld() ); //Get the stride(size) of the a vertex, we need this to tell the pipeline the size of one vertex UINT stride = m_pTestRenderable->getStride(); //The offset from start of the buffer to where our vertices are located UINT offset = m_pTestRenderable->getOffset(); ID3D10Buffer * pVB=m_pTestRenderable->getVB(); //Bind the vertex buffer to input assembler stage - md3dDevice->IASetVertexBuffers( 0, 1, &pVB, &stride, &offset ); md3dDevice->IASetIndexBuffer( m_pTestRenderable->getIB(), DXGI_FORMAT_R32_UINT, 0 ); //Get the Description of the technique, we need this in order to loop through each pass in the technique D3D10_TECHNIQUE_DESC techDesc; m_pTechnique->GetDesc( &techDesc ); //Loop through the passes in the technique for( UINT p = 0; p < techDesc.Passes; ++p ) { //Get a pass at current index and apply it m_pTechnique->GetPassByIndex( p )->Apply( 0 ); //Draw call md3dDevice->DrawIndexed(m_pTestRenderable->getNumOfIndices(),0,0); //m_pD3D10Device->Draw(m_pTestRenderable->getNumOfVerts(),0); } Is there anything I've clearly done wrong or are missing? Spent 2 weeks trying to workout what on earth I've done wrong to no avail. Any insight a fresh pair eyes could give on this would be great.

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  • Geometry Shader input vertices order

    - by NPS
    MSDN specifies (link) that when using triangleadj type of input to the GS, it should provide me with 6 vertices in specific order: 1st vertex of the triangle processed, vertex of an adjacent triangle, 2nd vertex of the triangle processed, another vertex of an adjacent triangle and so on... So if I wanted to create a pass-through shader (i.e. output the same triangle I got on input and nothing else) I should return vertices 0, 2 and 4. Is that correct? Well, apparently it isn't because I did just that and when I ran my app the vertices were flickering (like changing positions/disappearing/showing again or sth like that). But when I instead output vertices 0, 1 and 2 the app rendered the mesh correctly. I could provide some code but it seems like the problem is in the input vertices order, not the code itself. So what order do input vertices to the GS come in?

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  • geomipmapping using displacement mapping (and glVertexAttribDivisor)

    - by Will
    I wake up with a clear vision, but sadly my laptop card doesn't do displacement mapping nor glVertexAttribDivisor so I can't test it out; I'm left sharing here: With geomipmapping, the grid at any factor is transposable - if you pass in an offset - say as a uniform - you can reuse the same vertex and index array again and again. If you also pass in the offset into the heightmap as a uniform, the vertex shader can do displacement mapping. If the displacement map is mipmapped, you get the advantages of trilinear filtering for distant maps. And, if the scenery is closer, rather than exposing that the you have a world made out of quads, you can use your transposable grid vertex array and indices to do vertex-shader interpolation (fancy splines) to do super-smooth infinite zoom? So I have some questions: does it work? In theory, in practice? does anyone do it? Does this technique have a name? Papers, demos, anything I can look at? does glVertexAttribDivisor mean that you can have a single glMultiDrawElementsEXT or similar approach to draw all your terrain tiles in one call rather than setting up the uniforms and emitting each tile? Would this offer any noticeable gains? does a heightmap that is GL_LUMINANCE take just one byte per pixel(=vertex)? (On mainstream cards, obviously. Does storage vary in practice?) Does going to the effort of reusing the same vertices and indices mean that you can basically fill the GPU RAM with heightmap and not a lot else, giving you either bigger landscapes or more detailed landscapes/meshes for the same bang? is mipmapping the displacement map going to work? On future cards? Is it going to introduce unsurmountable inaccuracies if it is enabled?

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  • OpenGL sprites and point size limitation

    - by Srdan
    I'm developing a simple particle system that should be able to perform on mobile devices (iOS, Andorid). My plan was to use GL_POINT_SPRITE/GL_PROGRAM_POINT_SIZE method because of it's efficiency (GL_POINTS are enough), but after some experimenting, I found myself in a trouble. Sprite size is limited (to usually 64 pixels). I'm calculating size using this formula gl_PointSize = in_point_size * some_factor / distance_to_camera to make particle sizes proportional to distance to camera. But at some point, when camera is close enough, problem with size limitation emerges and whole system starts looking unrealistic. Is there a way to avoid this problem? If no, what's alternative? I was thinking of manually generating billboard quad for each particle. Now, I have some questions about that approach. I guess minimum geometry data would be four vertices per particle and index array to make quads from these vertices (with GL_TRIANGLE_STRIP). Additionally, for each vertex I need a color and texture coordinate. I would put all that in an interleaved vertex array. But as you can see, there is much redundancy. All vertices of same particle share same color value, and four texture coordinates are same for all particles. Because of how glDrawArrays/Elements works, I see no way to optimise this. Do you know of a better approach on how to organise per-particle data? Should I use buffers or vertex arrays, or there is no difference because each time I have to update all particles' data. About particles simulation... Where to do it? On CPU or on a vertex processors? Something tells me that mobile's CPU would do it faster than it's vertex unit (at least today in 2012 :). So, any advice on how to make a simple and efficient particle system without particle size limitation, for mobile device, would be appreciated. (animation of camera passing through particles should be realistic)

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  • Parenting Opengl with Groups in LibGDX

    - by Rudy_TM
    I am trying to make an object child of a Group, but this object has a draw method that calls opengl to draw in the screen. Its class its this public class OpenGLSquare extends Actor { private static final ImmediateModeRenderer renderer = new ImmediateModeRenderer10(); private static Matrix4 matrix = null; private static Vector2 temp = new Vector2(); public static void setMatrix4(Matrix4 mat) { matrix = mat; } @Override public void draw(SpriteBatch batch, float arg1) { // TODO Auto-generated method stub renderer.begin(matrix, GL10.GL_TRIANGLES); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x0, y0, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x0, y1, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x1, y1, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x1, y1, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x1, y0, 0f); renderer.color(color.r, color.g, color.b, color.a); renderer.vertex(x0, y0, 0f); renderer.end(); } } In my screen class I have this, i call it in the constructor MyGroupClass spriteLab = new MyGroupClass(spriteSheetLab); OpenGLSquare square = new OpenGLSquare(); square.setX0(100); square.setY0(200); square.setX1(400); square.setY1(280); square.color.set(Color.BLUE); square.setSize(); //spriteLab.addActorAt(0, clock); spriteLab.addActor(square); stage.addActor(spriteLab); And the render in the screen I have @Override public void render(float arg0) { this.gl.glClear(GL10.GL_COLOR_BUFFER_BIT |GL10.GL_DEPTH_BUFFER_BIT); stage.draw(); stage.act(Gdx.graphics.getDeltaTime()); } The problem its that when i use opengl with parent, it resets all the other chldren to position 0,0 and the opengl renderer paints the square in the exact position of the screen and not relative to the parent. I tried using batch.enableBlending() and batch.disableBlending() that fixes the position problem of the other children, but not the relative position of the opengl drawing and it also puts alpha to the glDrawing. What am i doing wrong?:/

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  • Why the overhead when allocating objects/arrays in Java?

    - by Gnijuohz
    How many bytes an array occupies in Java? Assume It's a 64bit machine and also assume there are N elements in an array, so all these elements would take up 2*N, 4*N or 8*N bytes for different types of array. And a lecture in Coursera says that it would occupy 2*N+24, 4*N+24 or 8*N+24 bytes for a N element array and the 24 bytes is called overhead, but didn't explain why the overhead is needed. Also objects have overheads, which is 16 bytes. What exactly are these overheads? What are these 24/16 bytes composed of? Also, do these overheads only exist in Java? How about C, C++ and Python?

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  • How does opengl-es 2 assemble primitives?

    - by stephelton
    Two things I'm quite confused about. 1) OpenGL ES 2.0 creates primitives before the vertex shader is invoked. Why, then, does it not automatically provide the vertex shader the position of the vertex? 2) OpenGL ES 2.0 supports glDrawElements(), but it does not support glEnableClientState() or GL_VERTEX_ARRAY, so how can this call possibly be used to construct primitives? NOTE: this is OpenGL ES 2.0, NOT normal OpenGL! Thanks!

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  • How best to merge/sort/page through tons of JSON arrays?

    - by Joshiatto
    Here's the scenario: Say you have millions of JSON documents stored as text files. Each JSON document is an array of "activity" objects, each of which contain a "created_datetime" attribute. What is the best way to merge/sort/filter/page through these activities via a web UI? For example, say we want to take a few thousand of the documents, merge them into a gigantic array, sort the array by the "created_datetime" attribute descending and then page through it 10 activities at a time. Also keep in mind that roughly 25% of these JSON documents are updated every day, and updates have to make it into the view within 5 minutes. My first thought is to parse all of the documents into an RDBMS table and then it would just be a simple query such as "select top 10 name, created_datetime from Activity where user_id=12345 order by created_datetime desc". Some have suggested I use NoSQL techniques such as hadoop or map/reduce instead. How exactly would this work? For more background, see: Why is NoSQL better for this scenario?

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  • Why does unity obj import flip my x coordinate?

    - by milkplus
    When I import my wavefront obj model into unity and then draw lines over it with the same coordinates in the obj file, the x coordinate is negated. I don't see any option in the importer that might be doing that. And I'm using the same localToWorldMatrix and the same coordinate data in the .obj file. Hmmm GL.PushMatrix(); GL.MultMatrix(transform.localToWorldMatrix); CreateMaterial(); lineMaterial.SetPass(0); GL.Color(new Color(0, 1, 0)); GL.Begin(GL.LINES); GL.Vertex(p1); GL.Vertex(p2); GL.Vertex(p2); GL.Vertex(p3); //... GL.End(); GL.PopMatrix();

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  • Finding the median of the merged array of two sorted arrays in O(logN)?

    - by user176517
    Refering to the solution present at MIT handout I have tried to figure out the solution myself but have got stuck and I believe I need help to understand the following points. In the function header used in the solution MEDIAN -SEARCH (A[1 . . l], B[1 . . m], max(1,n/2 - m), min(l, n/2)) I do not understand the last two arguments why not simply 1, l why the max and min respectively. Thanking You.

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  • what's the overhead when allocating objects/arrays in Java?

    - by Gnijuohz
    How many bytes an array occupies in Java? Assume It's a 64bit machine and also assume there are N elements in an array, so all these elements would take up 2*N, 4*N or 8*N bytes for different types of array. And a lecture in Coursera says that it would occupy 2*N+24, 4*N+24 or 8*N+24 bytes for a N element array and the 24 byte is called overhead, but didn't explain it. Also objects have overheads, which is 16 bytes. What exactly are these overheads? Also, do these overheads only exist in Java? How about C, C++ and Python?

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  • C Programming arrays, I dont understand how I would go about making this program, If anyone can just guide me through the basic outline please :) [on hold]

    - by Rashmi Kohli
    Problem The temperature of a car engine has been measured, from real-world experiments, as shown in the table and graph below: Time (min) Temperature (oC) 0 20 1 36 2 61 3 68 4 77 5 110 Use linear regression to find the engine’s temperature at 1.5 minutes, 4.3 minutes, and any other time specified by the user. Background In engineering, many times we measure several data points in an experiment, but then we need to predict a value that we have not measured which lies between two measured values, such as the problem statement above. If the relation between the measured parameters seems to be roughly linear, then we can use linear regression to find the relationship between those parameters. In the graph of the problem statement above, the relation seems to be roughly linear. Hence, we can apply linear regression to the above problem. Assuming y {y0, y1, …yn-1} has a linear relation with x {x0, x1, … xn-1}, we can say that: y = mx+b where m and b can be found with linear regression as follows: For the problem in this lab, using linear regression gives us the following line (in blue) compared to the measured curve (in red). As you can see, there is usually a difference between the measured values and the estimated (predicted) values. What linear regression does is to minimize those differences and still give us a straight line (blue). Other methods, such as non-linear regression, are also possible to achieve higher accuracy and better curve fitting. Requirements Your program should first print the table of the temperatures similar to the way it’s printed in the problem statement. It should then calculate the temperature at minute 1.5 and 4.3 and show the answers to the user. Next, it should prompt the user to enter a time in minutes (or -1 to quit), and after reading the user’s specified time it should give the value of the engine’s temperature at that time. It should then go back to the prompt. Hints •Use a one dimensional array to store the temperature values given in the problem statement. •Use functions to separate tasks such as calculating m, calculating b, calculating the temperature at a given time, printing the prompt, etc. You can then give your algorithm as well as you pseudo code per function, as opposed to one large algorithm diagram or one large sequence of pseudo code.

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  • How to make other semantics behave like SV_Position?

    - by object
    I'm having a lot of trouble with shadow mapping, and I believe I've found the problem. When passing vectors from the vertex shader to the pixel shader, does the hardware automatically change any of the values based on the semantic? I've compiled a barebones pair of shaders which should illustrate the problem. Vertex shader : struct Vertex { float3 position : POSITION; }; struct Pixel { float4 position : SV_Position; float4 light_position : POSITION; }; cbuffer Matrices { matrix projection; }; Pixel RenderVertexShader(Vertex input) { Pixel output; output.position = mul(float4(input.position, 1.0f), projection); output.light_position = output.position; // We simply pass the same vector in screenspace through different semantics. return output; } And a simple pixel shader to go along with it: struct Pixel { float4 position : SV_Position; float4 light_position : POSITION; }; float4 RenderPixelShader(Pixel input) : SV_Target { // At this point, (input.position.z / input.position.w) is a normal depth value. // However, (input.light_position.z / input.light_position.w) is 0.999f or similar. // If the primitive is touching the near plane, it very quickly goes to 0. return (0.0f).rrrr; } How is it possible to make the hardware treat light_position in the same way which position is being treated between the vertex and pixel shaders? EDIT: Aha! (input.position.z) without dividing by W is the same as (input.light_position.z / input.light_position.w). Not sure why this is.

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  • What is the minimum of shader I need to use to run basic calculation on GPU?

    - by Jinxi
    I read, that the Hull Shader, Domain Shader, Geometry Shader and Pixel Shader can be used optional. So, is the Vertex Shader optional too? If no: What does a basic Vertex Shader look like? Just like a simple pass through? Is the Vertex Shader necessary to tell what kind of datastructure (Van Stripes or Meshes) are used? What can I do, with just the vertex shader? Are the fixed functions working without any help of programming a programmable stage?

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  • Is there a more efficient way to filter large arrays than preg_match()?

    - by hozza
    I have a log that our web application builds. Each month it contains around 16,000 entries of a string with about the average sentence worth of text. To filter/search through these in our admin panel the script uses preg_match() but this seems to be taking ages and timing out on the 30sec limit. I have isolated that it is indeed the preg_match() that causes the time out. Is there a more efficient way to search through values in a large array for a users input?

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  • Why do arrays in java choose the biggest? [closed]

    - by Trycon
    I'm new to java so I was reading my book with these code: public class mainb1 { public static void main (String[] args) { //datatype name = expression; //food int min, max; int num[] = new int[10]; num[0]=99; num[1]=90; num[2]=-100; num[3]=100; num[4]=23; num[5]=50; num[6]=123; num[7]=3123; num[8]=2; num[9]=923; min=max=num[1]; for(int x=0;x<10;x++) { if(num[x]<min)min=num[x]; if(num[x]>max)max=num[x]; } System.out.println("Min: "+min+" max: "+max); } } It chose the biggest and the smallest. I don't get it if max was 99, then the last one that is lesser than min is 2? How did this array choose to pick the smallest and the biggest? Can someone explain?

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  • How would I detect if two 2D arrays of any shape collided?

    - by user2104648
    Say there's two or more moveable objects of any shape in 2D plane, each object has its own 2D boolean array to act as a bounds box which can range from 10 to 100 pixels, the program then reads each pixel from a image that represents it, and appropriatly changes the array to true(pixel has a alpha more then 1) or false(pixel has a alpha less than one). Each time one of these objects moves, what would be the best accurate way to test if they hit another object in Java using as few APIs/libraries as possible?

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  • OpenGL-ES: Change (multiply) color when using color arrays?

    - by arberg
    Following the ideas in OpenGL ES iPhone - drawing anti aliased lines, I am trying to draw stroked anti-aliased lines and I am successful so far. After line is draw by the finger, I wish to fade the path, that is I need to change the opacity (color) of the entire path. I have computed a large array of vertex positions, vertex colors, texture coordinates, and indices and then I give these to opengl but I would like reduce the opacity of all the drawn triangles without having to change each of the color coordinates. Normally I would use glColor4f(r,g,b,a) before calling drawElements, but it has no effect due to the color array. I am working on Android, but I believe it shouldn't make the big difference, as long as it is OpenGL-ES 1.1 (or 1.0). I have the following code : gl.glEnable(GL10.GL_BLEND); gl.glBlendFunc(GL10.GL_ONE, GL10.GL_ONE_MINUS_SRC_ALPHA); gl.glEnableClientState(GL10.GL_COLOR_ARRAY); gl.glShadeModel(GL10.GL_SMOOTH); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glEnable(GL10.GL_TEXTURE_2D); // Should set rgb to greyish, and alpha to half-transparent, the greyish is // just there to make the question more general its the alpha i'm interested in gl.glColor4f(.75f, .75f, .75f, 0.5f); gl.glVertexPointer(mVertexSize, GL10.GL_FLOAT, 0, mVertexBuffer); gl.glColorPointer(4, GL10.GL_FLOAT, 0, mColorBuffer); gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, mTexCoordBuffer); gl.glDrawElements(GL10.GL_TRIANGLES, indexCount, GL10.GL_UNSIGNED_SHORT, mIndexBuffer.position(startIndex)); If I disable the color array gl.glEnableClientState(GL10.GL_COLOR_ARRAY);, then the glColor4f works, if I enable the color array it does nothing. Is there any way in OpenGl-ES to change the coloring without changing all the color coordinates? I think that in OpenGl one might use a fragment shader, but it seems OpenGL does not have a fragment shader (not that I know how to use one).

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