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  • Problems with texture orientation in space

    - by frankie
    I am currently drawing texture in 3D space and have some problems with it's orientation. I'd like me textures always to be oriented with front face to user. My desirable result looks like Note, that text size stay without changes when we rotating world and stay oriented with front face to user. Now I can draw text in 3D space, but it is not oriented with front but rotating with world. Such results I got with following shaders: Vertex Shader uniform vec3 Position; void main() { gl_Position = vec4(Position, 1.0); } Geometry Shader layout(points) in; layout(triangle_strip, max_vertices = 4) out; out vec2 fsTextureCoordinates; uniform mat4 projectionMatrix; uniform mat4 modelViewMatrix; uniform sampler2D og_texture0; uniform float og_highResolutionSnapScale; uniform vec2 u_originScale; void main() { vec2 halfSize = vec2(textureSize(og_texture0, 0)) * 0.5 * og_highResolutionSnapScale; vec4 center = gl_in[0].gl_Position; center.xy += (u_originScale * halfSize); vec4 v0 = vec4(center.xy - halfSize, center.z, 1.0); vec4 v1 = vec4(center.xy + vec2(halfSize.x, -halfSize.y), center.z, 1.0); vec4 v2 = vec4(center.xy + vec2(-halfSize.x, halfSize.y), center.z, 1.0); vec4 v3 = vec4(center.xy + halfSize, center.z, 1.0); gl_Position = projectionMatrix * modelViewMatrix * v0; fsTextureCoordinates = vec2(0.0, 0.0); EmitVertex(); gl_Position = projectionMatrix * modelViewMatrix * v1; fsTextureCoordinates = vec2(1.0, 0.0); EmitVertex(); gl_Position = projectionMatrix * modelViewMatrix * v2; fsTextureCoordinates = vec2(0.0, 1.0); EmitVertex(); gl_Position = projectionMatrix * modelViewMatrix * v3; fsTextureCoordinates = vec2(1.0, 1.0); EmitVertex(); } Fragment Shader in vec2 fsTextureCoordinates; out vec4 fragmentColor; uniform sampler2D og_texture0; uniform vec3 u_color; void main() { vec4 color = texture(og_texture0, fsTextureCoordinates); if (color.a == 0.0) { discard; } fragmentColor = vec4(color.rgb * u_color.rgb, color.a); } Any ideas how to get my desirable result? EDIT 1: I make edit in my geometry shader and got part of lable drawn on screen at corner. But it is not rotating. .......... vec4 centerProjected = projectionMatrix * modelViewMatrix * center; centerProjected /= centerProjected.w; vec4 v0 = vec4(centerProjected.xy - halfSize, 0.0, 1.0); vec4 v1 = vec4(centerProjected.xy + vec2(halfSize.x, -halfSize.y), 0.0, 1.0); vec4 v2 = vec4(centerProjected.xy + vec2(-halfSize.x, halfSize.y), 0.0, 1.0); vec4 v3 = vec4(centerProjected.xy + halfSize, 0.0, 1.0); gl_Position = og_viewportOrthographicMatrix * v0; ..........

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  • Computing a normal matrix in conjunction with gluLookAt

    - by Chris Smith
    I have a hand-rolled camera class that converts yaw, pitch, and roll angles into a forward, side, and up vector suitable for calling gluLookAt. Using this camera class I can modify the model-view matrix to move about the 3D world just fine. However, I am having trouble when using this camera class (and associated model-view matrix) when trying to perform directional lighting in my vertex shader. The problem is that the light direction, (0, 1, 0) for example, is relative to where the 'camera is looking' and not the actual world coordinates. (Or is this eye coordinates vs. model coordinates?) I would like the light direction to be unaffected by the camera's viewing direction. For example, when the camera is looking down the Z axis the ground is lit correctly. However, if I point the camera straight at the ground, then it goes dark. This is (I think) because the light direction is parallel with the camera's 'up' vector which is perpendicular with the ground's normal vector. I tried computing the normal matrix without taking the camera's model view into account, but then none of my objects were rotated correctly. Sorry if this sounds vague. I suspect there is a straight forward answer, but I'm not 100% clear on how the normal matrix should be used for transforming vertex normals in my vertex shader. For reference, here is pseudo code for my rendering loop: pMatrix = new Matrix(); pMatrix = makePerspective(...) mvMatrix = new Matrix() camera.apply(mvMatrix); // Calls gluLookAt // Move the object into position. mvMatrix.translatev(position); mvMatrix.rotatef(rotation.x, 1, 0, 0); mvMatrix.rotatef(rotation.y, 0, 1, 0); mvMatrix.rotatef(rotation.z, 0, 0, 1); var nMatrix = new Matrix(); nMatrix.set(mvMatrix.get().getInverse().getTranspose()); // Set vertex shader uniforms. gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, new Float32Array(pMatrix.getFlattened())); gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, new Float32Array(mvMatrix.getFlattened())); gl.uniformMatrix4fv(shaderProgram.nMatrixUniform, false, new Float32Array(nMatrix.getFlattened())); // ... gl.drawElements(gl.TRIANGLES, this.vertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0); And the corresponding vertex shader: // Attributes attribute vec3 aVertexPosition; attribute vec4 aVertexColor; attribute vec3 aVertexNormal; // Uniforms uniform mat4 uMVMatrix; uniform mat4 uNMatrix; uniform mat4 uPMatrix; // Varyings varying vec4 vColor; // Constants const vec3 LIGHT_DIRECTION = vec3(0, 1, 0); // Opposite direction of photons. const vec4 AMBIENT_COLOR = vec4 (0.2, 0.2, 0.2, 1.0); float ComputeLighting() { vec4 transformedNormal = vec4(aVertexNormal.xyz, 1.0); transformedNormal = uNMatrix * transformedNormal; float base = dot(normalize(transformedNormal.xyz), normalize(LIGHT_DIRECTION)); return max(base, 0.0); } void main(void) { gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0); float lightWeight = ComputeLighting(); vColor = vec4(aVertexColor.xyz * lightWeight, 1.0) + AMBIENT_COLOR; } Note that I am using WebGL, so if the anser is use glFixThisProblem(...) any pointers on how to re-implement that on WebGL if missing would be appreciated.

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  • C++ OpenGL wireframe cube rendering blank

    - by caleb.breckon
    I'm just trying to draw a bunch of lines that make up a "cube". I can't for the life of me figure out why this is producing a black screen. The debugger does not break at any point. I'm sure it's a problem with my pointers, as I'm only decent at them in regular c++ and in OpenGL it gets even worse. const char* vertexSource = "#version 150\n" "in vec3 position;" "void main() {" " gl_Position = vec4(position, 1.0);" "}"; const char* fragmentSource = "#version 150\n" "out vec4 outColor;" "void main() {" " outColor = vec4(1.0, 1.0, 1.0, 1.0);" "}"; int main() { initializeGLFW(); // Initialize GLEW glewExperimental = GL_TRUE; glewInit(); // Create Vertex Array Object GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); // Create a Vertex Buffer Object and copy the vertex data to it GLuint vbo; glGenBuffers( 1, &vbo ); float vertices[] = { 1.0f, 1.0f, 1.0f, // Vertex 0 (X, Y, Z) -1.0f, 1.0f, 1.0f, // Vertex 1 (X, Y, Z) -1.0f, -1.0f, 1.0f, // Vertex 2 (X, Y, Z) 1.0f, -1.0f, 1.0f, // Vertex 3 (X, Y, Z) 1.0f, 1.0f, -1.0f, // Vertex 4 (X, Y, Z) -1.0f, 1.0f, -1.0f, // Vertex 5 (X, Y, Z) -1.0f, -1.0f, -1.0f, // Vertex 6 (X, Y, Z) 1.0f, -1.0f, -1.0f // Vertex 7 (X, Y, Z) }; GLuint indices[] = { 0, 1, 1, 2, 2, 3, 3, 0, 4, 5, 5, 6, 6, 7, 7, 4, 0, 4, 1, 5, 2, 6, 3, 7 }; glBindBuffer( GL_ARRAY_BUFFER, vbo ); glBufferData( GL_ARRAY_BUFFER, sizeof( vertices ), vertices, GL_STATIC_DRAW ); //glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, vbo); //glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof( indices ), indices, GL_STATIC_DRAW ); // Create and compile the vertex shader GLuint vertexShader = glCreateShader( GL_VERTEX_SHADER ); glShaderSource( vertexShader, 1, &vertexSource, NULL ); glCompileShader( vertexShader ); // Create and compile the fragment shader GLuint fragmentShader = glCreateShader( GL_FRAGMENT_SHADER ); glShaderSource( fragmentShader, 1, &fragmentSource, NULL ); glCompileShader( fragmentShader ); // Link the vertex and fragment shader into a shader program GLuint shaderProgram = glCreateProgram(); glAttachShader( shaderProgram, vertexShader ); glAttachShader( shaderProgram, fragmentShader ); glBindFragDataLocation( shaderProgram, 0, "outColor" ); glLinkProgram (shaderProgram); glUseProgram( shaderProgram); // Specify the layout of the vertex data GLint posAttrib = glGetAttribLocation( shaderProgram, "position" ); glEnableVertexAttribArray( posAttrib ); glVertexAttribPointer( posAttrib, 3, GL_FLOAT, GL_FALSE, 0, 0 ); // Main loop while(glfwGetWindowParam(GLFW_OPENED)) { // Clear the screen to black glClearColor( 0.0f, 0.0f, 0.0f, 1.0f ); glClear( GL_COLOR_BUFFER_BIT ); // Draw lines from 2 vertices glDrawElements(GL_LINES, sizeof(indices), GL_UNSIGNED_INT, indices ); // Swap buffers glfwSwapBuffers(); } // Clean up glDeleteProgram( shaderProgram ); glDeleteShader( fragmentShader ); glDeleteShader( vertexShader ); //glDeleteBuffers( 1, &ebo ); glDeleteBuffers( 1, &vbo ); glDeleteVertexArrays( 1, &vao ); glfwTerminate(); exit( EXIT_SUCCESS ); }

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  • Getting the number of fragments which passed the depth test

    - by Etan
    In "modern" environments, the "NV Occlusion Query" extension provides a method to get the number of fragments which passed the depth test. However, on the iPad / iPhone using OpenGL ES, the extension is not available. What is the most performant approach to implement a similar behaviour in the fragment shader? Some of my ideas: Render the object completely in white, then count all the colors together using a two-pass shader where first a vertical line is rendered and for each fragment the shader computes the sum over the whole row. Then, a single vertex is rendered whose fragment sums all the partial sums of the first pass. Doesn't seem to be very efficient. Render the object completely in white over a black background. Downsample recursively, abusing the hardware linear interpolation between textures until being at a reasonably small resolution. This leads to fragments which have a greyscale level depending on the number of white pixels where in their corresponding region. Is this even accurate enough? Use mipmaps and simply read the pixel on the 1x1 level. Again the question of accuracy and if it is even possible using non-power-of-two textures. The problem wit these approaches is, that the pipeline gets stalled which results in major performance issues. Therefore, I'm looking for a more performant way to accomplish my goal. Using the EXT_OCCLUSION_QUERY_BOOLEAN extension Apple introduced EXT_OCCLUSION_QUERY_BOOLEAN in iOS 5.0 for iPad 2. "4.1.6 Occlusion Queries Occlusion queries use query objects to track the number of fragments or samples that pass the depth test. An occlusion query can be started and finished by calling BeginQueryEXT and EndQueryEXT, respectively, with a target of ANY_SAMPLES_PASSED_EXT or ANY_SAMPLES_PASSED_CONSERVATIVE_EXT. When an occlusion query is started with the target ANY_SAMPLES_PASSED_EXT, the samples-boolean state maintained by the GL is set to FALSE. While that occlusion query is active, the samples-boolean state is set to TRUE if any fragment or sample passes the depth test. When the occlusion query finishes, the samples-boolean state of FALSE or TRUE is written to the corresponding query object as the query result value, and the query result for that object is marked as available. If the target of the query is ANY_SAMPLES_PASSED_CONSERVATIVE_EXT, an implementation may choose to use a less precise version of the test which can additionally set the samples-boolean state to TRUE in some other implementation dependent cases." The first sentence hints on a behavior which is exactly what I'm looking for: getting the number of pixels which passed the depth test in an asynchronous manner without much performance loss. However, the rest of the document describes only how to get boolean results. Is it possible to exploit this extension to get the pixel count? Does the hardware support it so that there may be hidden API to get access to the pixel count? Other extensions which could be exploitable would be debugging features like the number of times the fragment shader was invoked (PSInvocations in DirectX - not sure if something simila is available in OpenGL ES). However, this would also result in a pipeline stall.

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  • Ogre material scripts; how do I give a technique multiple lod_indexes?

    - by BlueNovember
    I have an Ogre material script that defines 4 rendering techniques. 1 using GLSL shaders, then 3 others that just use textures of different resolutions. I want to use the GLSL shader unconditionally if the graphics card supports it, and the other 3 textures depending on camera distance. At the moment my script is; material foo { lod_distances 1600 2000 technique shaders { lod_index 0 lod_index 1 lod_index 2 //various passes here } technique high_res { lod_index 0 //various passes here } technique medium_res { lod_index 1 //various passes here } technique low_res { lod_index 2 //various passes here } Extra information The Ogre manual says; Increasing indexes denote lower levels of detail You can (and often will) assign more than one technique to the same LOD index, what this means is that OGRE will pick the best technique of the ones listed at the same LOD index. OGRE determines which one is 'best' by which one is listed first. Currently, on a machine supporting the GLSL version I am using, the script behaves as follows; Camera 2000 : Shader technique Camera 1600 <= 2000 : Medium Camera <= 1600 : High If I change the lod order in shader technique to { lod_index 2 lod_index 1 lod_index 0 } The behaviour becomes; Camera 2000 : Low Camera 1600 <= 2000 : Medium Camera <= 1600 : Shader implying only the latest lod_index is used. If I change it to lod_index 0 1 2 It shouts at me Compiler error: fewer parameters expected in foo.material(#): lod_index only supports 1 argument So how do I specify a technique to have 3 lod_indexes? Duplication works; technique shaders { lod_index 0 //various passes here } technique shaders1 { lod_index 1 //passes repeated here } technique shaders2 { lod_index 2 //passes repeated here } ...but it's ugly.

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  • How to Stich to Image objects in Java

    - by Imran
    Hi, I have a scenario in which i`m getting a number of tiles (e.g.12) from my mapping server. Now for buffering and offline functions I need to join them all back again so that we have to deal with 1 single image object instead of 12. I ve tried to do it without JAI my code is below. package imagemerge; import java.awt.*; import java.awt.image.*; import java.awt.event.*; public class ImageSticher extends WindowAdapter { Image tile1; Image tile2; Image result; ColorModel colorModel; int width,height,widthr,heightr; //int t1,t2; int t12[]; public ImageSticher() { } public ImageSticher (Image img1,Image img2,int w,int h) { tile1=img1; tile2=img2; width=w; height=h; colorModel=ColorModel.getRGBdefault(); } public Image horizontalStich() throws Exception { widthr=width*2; heightr=height; t12=new int[widthr * heightr]; int t1[]=new int[width*height]; PixelGrabber p1 =new PixelGrabber(tile1, 0, 0, width, height, t1, 0, width); p1.grabPixels(); int t2[]=new int[width*height]; PixelGrabber p2 =new PixelGrabber(tile2, 0, 0, width, height, t1, 0, width); p2.grabPixels(); int y, x, rp, rpi; int red1, red2, redr; int green1, green2, greenr; int blue1, blue2, bluer; int alpha1, alpha2, alphar; for(y=0;y<heightr;y++) { for(x=0;x<widthr;x++) { //System.out.println(x); rpi=y*widthr+x; // index of resulting pixel; rp=0; //initializing resulting pixel System.out.println(rpi); if(x<(widthr/2)) // x is less than width , copy first tile { //System.out.println("tile1="+x); blue1 = t1[rpi] & 0x00ff; // ERROR occurs here green1=(t1[rpi] >> 8) & 0x00ff; red1=(t1[rpi] >> 16) & 0x00ff; alpha1 = (t1[rpi] >> 24) & 0x00ff; redr = (int)(red1 * 1.0); // copying red band pixel into redresult,,,,1.0 is the alpha valye redr = (redr < 0)?(0):((redr>255)?(255):(redr)); greenr = (int)(green1 * 1.0); // redr = (int)(red1 * 1.0); // greenr = (greenr < 0)?(0):((greenr>255)?(255):(greenr)); bluer = (int)(blue1 * 1.0); bluer = (bluer < 0)?(0):((bluer>255)?(255):(bluer)); alphar = 255; //resulting pixel computed rp = (((((alphar << 8) + (redr & 0x0ff)) << 8) + (greenr & 0x0ff)) << 8) + (bluer & 0x0ff); } else // index is ahead of half way...copy second tile { blue2 = t2[rpi] & 0x00ff; // blue band bit of first tile green2=(t2[rpi] >> 8) & 0x00ff; red2=(t2[rpi] >> 16) & 0x00ff; alpha2 = (t2[rpi] >> 24) & 0x00ff; redr = (int)(red2 * 1.0); // copying red band pixel into redresult,,,,1.0 is the alpha valye redr = (redr < 0)?(0):((redr>255)?(255):(redr)); greenr = (int)(green2 * 1.0); // redr = (int)(red2 * 1.0); // greenr = (greenr < 0)?(0):((greenr>255)?(255):(greenr)); bluer = (int)(blue2 * 1.0); bluer = (bluer < 0)?(0):((bluer>255)?(255):(bluer)); alphar = 255; //resulting pixel computed rp = (((((alphar << 8) + (redr & 0x0ff)) << 8) + (greenr & 0x0ff)) << 8) + (bluer & 0x0ff); } t12[rpi] = rp; // copying resulting pixel in the result int array which will be converted to image } } MemoryImageSource mis; if (t12!=null) { mis = new MemoryImageSource(widthr, heightr, colorModel, t12, 0, widthr); result = Toolkit.getDefaultToolkit().createImage(mis); return result; } return null; } } now to check the my theory Im trying to join or stich two tiles horizontaly but im getting the error : java.lang.ArrayIndexOutOfBoundsException: 90000 at imagemerge.ImageSticher.horizontalStich(ImageSticher.java:69) at imageStream.ImageStream.getImage(ImageStream.java:75) at imageStream.ImageStream.main(ImageStream.java:28) is there some kind of limitation because when stiching two images of 300 x 300 horizontally it means the resulting image will be 600 x 300 ... that would make 180000 index size but its giving error at 90000, what am I doing wrong here

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  • What is the significance of these different width, height and resolution parameters?

    - by ??????? ???????????
    An image with a pixel resolution of 640 x 480 has additional dimension and resolution parameters according to exiftool. I'm unsure what they mean. Why are the X / Y Resolution parameters the same?Should they not reflect the pixel dimensions of the image? What does Exif Image Size mean and how is it different from the pixel dimensions? What is the focal plane? Does it have any relation to the device used to capture this image? $ exiftool evil1.jpg | egrep 'Width|Height|Resolution' X Resolution : 180 Y Resolution : 180 Resolution Unit : inches Exif Image Width : 400 Exif Image Height : 300 Focal Plane X Resolution : 8114.285714 Focal Plane Y Resolution : 8114.285714 Focal Plane Resolution Unit : inches Image Width : 640 Image Height : 480 If needed, the original image can be obtained from: here=http://www.pythonchallenge.com/pc/return/evil1.jpg wget --user=huge --password=file $here

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  • image processing algorithm in MATLAB

    - by user261002
    I am trying to reconstruct an algorithm belong to this paper: Decomposition of biospeckle images in temporary spectral bands Here is an explanation of the algorithm: We recorded a sequence of N successive speckle images with a sampling frequency fs. In this way it was possible to observe how a pixel evolves through the N images. That evolution can be treated as a time series and can be processed in the following way: Each signal corresponding to the evolution of every pixel was used as input to a bank of filters. The intensity values were previously divided by their temporal mean value to minimize local differences in reflectivity or illumination of the object. The maximum frequency that can be adequately analyzed is determined by the sampling theorem and s half of sampling frequency fs. The latter is set by the CCD camera, the size of the image, and the frame grabber. The bank of filters is outlined in Fig. 1. In our case, ten 5° order Butterworth11 filters were used, but this number can be varied according to the required discrimination. The bank was implemented in a computer using MATLAB software. We chose the Butter-worth filter because, in addition to its simplicity, it is maximally flat. Other filters, an infinite impulse response, or a finite impulse response could be used. By means of this bank of filters, ten corresponding signals of each filter of each temporary pixel evolution were obtained as output. Average energy Eb in each signal was then calculated: where pb(n) is the intensity of the filtered pixel in the nth image for filter b divided by its mean value and N is the total number of images. In this way, en values of energy for each pixel were obtained, each of hem belonging to one of the frequency bands in Fig. 1. With these values it is possible to build ten images of the active object, each one of which shows how much energy of time-varying speckle there is in a certain frequency band. False color assignment to the gray levels in the results would help in discrimination. and here is my MATLAB code base on that : clear all for i=0:39 str = num2str(i); str1 = strcat(str,'.mat'); load(str1); D{i+1}=A; end new_max = max(max(A)); new_min = min(min(A)); for i=20:180 for j=20:140 ts = []; for k=1:40 ts = [ts D{k}(i,j)]; %%% kth image pixel i,j --- ts is time series end ts = double(ts); temp = mean(ts); ts = ts-temp; ts = ts/temp; N = 5; % filter order W = [0.00001 0.05;0.05 0.1;0.1 0.15;0.15 0.20;0.20 0.25;0.25 0.30;0.30 0.35;0.35 0.40;0.40 0.45;0.45 0.50]; N1 = 5; for ind = 1:10 Wn = W(ind,:); [B,A] = butter(N1,Wn); ts_f(ind,:) = filter(B,A,ts); end for ind=1:10 imag_test1{ind}(i,j) =sum((ts_f(ind,:)./mean(ts_f(ind,:))).^2); end end end for i=1:10 temp_imag = imag_test1{i}(:,:); x=isnan(temp_imag); temp_imag(x)=0; temp_imag=medfilt2(temp_imag); t_max = max(max(temp_imag)); t_min = min(min(temp_imag)); temp_imag = (temp_imag-t_min).*(double(new_max-new_min)/double(t_max-t_min))+double(new_min); imag_test2{i}(:,:) = temp_imag; end for i=1:10 A=imag_test2{i}(:,:); B=A/max(max(A)); B=histeq(B); figure,imshow(B) colorbar end but I am not getting the same result as paper. has anybody has aby idea why? or where I have gone wrong? Refrence Link to the paper

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  • Drawing outlines around organic shapes

    - by ThunderChunky_SF
    One thing that seems particularly easy to do in the Flash IDE but difficult to do with code is to outline an organic shape. In the IDE you can just use the inkbucket tool to draw a stroke around something. Using nothing but code it seems much trickier. One method I've seen is to add a glow filter to the shape in question and just mess with the strength. But what if i want to only show the outline? What I'd like to do is to collect all of the points that make up the edge of the shape and then just connect the dots. I've actually gotten so far as to collect all of the points with a quick and dirty edge detection script that I wrote. So now I have a Vector of all the points that makeup my shape. How do I connect them in the proper sequence so it actually looks like the original object? For anyone who is interested here is my edge detection script: // Create a new sprite which we'll use for our outline var sp:Sprite = new Sprite(); var radius:int = 50; sp.graphics.beginFill(0x00FF00, 1); sp.graphics.drawCircle(0, 0, radius); sp.graphics.endFill(); sp.x = stage.stageWidth / 2; sp.y = stage.stageHeight / 2; // Create a bitmap data object to draw our vector data var bmd:BitmapData = new BitmapData(sp.width, sp.height, true, 0); // Use a transform matrix to translate the drawn clip so that none of its // pixels reside in negative space. The draw method will only draw starting // at 0,0 var mat:Matrix = new Matrix(1, 0, 0, 1, radius, radius); bmd.draw(sp, mat); // Pass the bitmap data to an actual bitmap var bmp:Bitmap = new Bitmap(bmd); // Add the bitmap to the stage addChild(bmp); // Grab all of the pixel data from the bitmap data object var pixels:Vector.<uint> = bmd.getVector(bmd.rect); // Setup a vector to hold our stroke points var points:Vector.<Point> = new Vector.<Point>; // Loop through all of the pixels of the bitmap data object and // create a point instance for each pixel location that isn't // transparent. var l:int = pixels.length; for(var i:int = 0; i < l; ++i) { // Check to see if the pixel is transparent if(pixels[i] != 0) { var pt:Point; // Check to see if the pixel is on the first or last // row. We'll grab everything from these rows to close the outline if(i <= bmp.width || i >= (bmp.width * bmp.height) - bmp.width) { pt = new Point(); pt.x = int(i % bmp.width); pt.y = int(i / bmp.width); points.push(pt); continue; } // Check to see if the current pixel is on either extreme edge if(int(i % bmp.width) == 0 || int(i % bmp.width) == bmp.width - 1) { pt = new Point(); pt.x = int(i % bmp.width); pt.y = int(i / bmp.width); points.push(pt); continue; } // Check to see if the previous or next pixel are transparent, // if so save the current one. if(i > 0 && i < bmp.width * bmp.height) { if(pixels[i - 1] == 0 || pixels[i + 1] == 0) { pt = new Point(); pt.x = int(i % bmp.width); pt.y = int(i / bmp.width); points.push(pt); } } } }

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  • Fastest way to read data from a lot of ASCII files

    - by Alsenes
    Hi guys, for a college exercise that I've already submitted I needed to read a .txt file wich contained a lot of names of images(1 in each line). Then I needed to open each image as an ascii file, and read their data(images where in ppm format), and do a series of things with them. The things is, I noticed my program was taking 70% of the time in the reading the data from the file part, instead of in the other calculations that I was doing (finding number of repetitions of each pixel with a hash table, finding diferents pixels beetween 2 images etc..), which I found quite odd to say the least. This is how the ppm format looks like: P3 //This value can be ignored when reading the file, because all image will be correctly formatted 4 4 255 //This value can be also ignored, will be always 255. 0 0 0 0 0 0 0 0 0 15 0 15 0 0 0 0 15 7 0 0 0 0 0 0 0 0 0 0 0 0 0 15 7 0 0 0 15 0 15 0 0 0 0 0 0 0 0 0 This is how I was reading the data from the files: ifstream fdatos; fdatos.open(argv[1]); //Open file with the name of all the images const int size = 128; char file[size]; //Where I'll get the image name Image *img; while (fdatos >> file) { //While there's still images anmes left, continue ifstream fimagen; fimagen.open(file); //Open image file img = new Image(fimagen); //Create new image object with it's data file ……… //Rest of the calculations whith that image ……… delete img; //Delete image object after done fimagen.close(); //Close image file after done } fdatos.close(); And inside the image object read the data like this: const int tallafirma = 100; char firma[tallafirma]; fich_in >> std::setw(100) >> firma; // Read the P3 part, can be ignored int maxvalue, numpixels; fich_in >> height >> width >> maxvalue; // Read the next three values numpixels = height*width; datos = new Pixel[numpixels]; int r,g,b; //Don't need to be ints, max value is 256, so an unsigned char would be ok. for (int i=0; i<numpixels; i++) { fich_in >> r >> g >> b; datos[i] = Pixel( r, g ,b); } //This last part is the slow one, //I thing I should be able to read all this data in one single read //to buffer or something which would be stored in an array of unsigned chars, //and then I'd only need to to do: //buffer[0] -> //Pixel 1 - Red data //buffer[1] -> //Pixel 1 - Green data //buffer[2] -> //Pixel 1 - Blue data So, any Ideas? I think I can improve it quite a bit reading all to an array in one single call, I just don't know how that is done. Also, is it posible to know how many images will be in the "index file"? Is it posiible to know the number of lines a file has?(because there's one file name per line..) Thanks!!

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  • Are there any font rendering libraries for games development that support hinting?

    - by Richard Fabian
    I've used angel code's bitmap font generator quite a bit and though it's very good, I wondered if there would be a way of using the hinting information to provide a better readable result by using hinting to provide differing thickness based on size/pixel coverage. I imagine any solution would have to use the distance field tech presented in the valve paper on smoothing fonts while maintaining or reducing asset size. (http://www.gamedev.net/community/forums/topic.asp?topic_id=494612) but I haven't found any demos of it being used with hinting information turned on or included in the field gradients in any way. Another way of looking at this is whether there are any font bitmap generators that will output mipmaps that still maintain their readability in the face of pixel size. I think the lower mip levels would try to guarantee fill and space where it is necessary to maintain readability/topology over maintaining style/form (the point of hinting). In response to "Is there a reason you can't just render the size you want", the problem lies in the fact that font rasterisers currently don't render in 3D, and hinting information would be important in different amounts due to the pixel density being different along different axes, even differing in importance along the length of a string due to the size reducing over distance. For example, I only want horizontal hinting in a texture that is viewed from the side, and only really want vertical hinting in a font that is viewed from below or above. This isn't meant to be a renderer that tries to render a perfect outline as accurately as possible, as hinting distorts the reality of the font, instead this is meant to be a rendering solution for quite static scenes, but scenes that have 3D transformed and warped text layout. In this case the legibility is important, more important than the accuracy of representation of the polygon shape.

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  • How do graphics programmers deal with rendering vertices that don't change the image?

    - by canisrufus
    So, the title is a little awkward. I'll give some background, and then ask my question. Background: I work as a web GIS application developer, but in my spare time I've been playing with map rendering and improving data interchange formats. I work only in 2D space. One interesting issue I've encountered is that when you're rendering a polygon at a small scale (zoomed way out), many of the vertices are redundant. An extreme case would be that you have a polygon with 500,000 vertices that only takes up a single pixel. If you're sending this data to the browser, it would make sense to omit ~499,999 of those vertices. One way we achieve that is by rendering an image on a server and and sending it as a PNG: voila, it's a point. Sometimes, though, we want data sent to the browser where it can be rendered with SVG (or canvas, or webgl) so that it can be interactive. The problem: It turns out that, using modern geographic data sets, it's very easy to overload SVG's rendering abilities. In an effort to cope with those limitations, I'm trying to figure out how to visually losslessly reduce a data set for a given scale and map extent (and, if necessary, for a known map pixel width and height). I got a great reduction in data size just using the Douglas-Peucker algorithm, and I believe I was able to get it to keep the polygons true to within one pixel. Unfortunately, Douglas-Peucker doesn't preserve topology, so it changed how borders between polygons got rendered. I couldn't readily find other algorithms to try out and adapt to the purpose, but I don't have much CS/algorithm background and might not recognize them if I saw them.

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  • Orthographic unit translation mismatch on grid (e.g. 64 pixels translates incorrectly)

    - by Justin Van Horne
    I am looking for some insight into a small problem with unit translations on a grid. Setup 512x448 window 64x64 grid gl_Position = projection * world * position; projection is defined by ortho(-w/2.0f, w/2.0f, -h/2.0f, h/2.0f); This is a textbook orthogonal projection function. world is defined by a fixed camera position at (0, 0) position is defined by the sprite's position. Problem In the screenshot below (1:1 scaling) the grid spacing is 64x64 and I am drawing the unit at (64, 64), however the unit draws roughly ~10px in the wrong position. I've tried uniform window dimensions to prevent any distortion on the pixel size, but now I am a bit lost in the proper way in providing a 1:1 pixel-to-world-unit projection. Anyhow, here are some quick images to aide in the problem. I decided to super-impose a bunch of the sprites at what the engine believes is 64x offsets. When this seemed off place, I went about and did the base case of 1 unit. Which seemed to line up as expected. The yellow shows a 1px difference in the movement. Vertices It would appear that the vertices going into the vertex shader are correct. For example, in reference to the first image the data looks like this in the VBO: x y x y ---------------------------- tl | 0.0 24.0 64.0 24.0 bl | 0.0 0.0 -> 64.0 0.0 tr | 16.0 0.0 80.0 0.0 br | 16.0 24.0 80.0 24.0 With that said, all I am left to believe is that I am munging up my actual projection. So, I am looking for any insight into maintaining the 1:1 pixel-to-world-unit projection.

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  • How to Detect Sprites in a SpriteSheet?

    - by IAE
    I'm currently writing a Sprite Sheet Unpacker such as Alferds Spritesheet Unpacker. Now, before this is sent to gamedev, this isn't necessarily about games. I would like to know how to detect a sprite within a spriitesheet, or more abstactly, a shape inside of an image. Given this sprite sheet: I want to detect and extract all individual sprites. I've followed the algorithm detailed in Alferd's Blog Post which goes like: Determine predominant color and dub it the BackgroundColor Iterate over each pixel and check ColorAtXY == BackgroundColor If false, we've found a sprite. Keep going right until we find a BackgroundColor again, backtrack one, go down and repeat until a BackgroundColor is reached. Create a box from location to ending location. Repeat this until all sprites are boxed up. Combined overlapping boxes (or within a very short distance) The resulting non-overlapping boxes should contain the sprite. This implementation is fine, especially for small sprite sheets. However, I find the performance too poor for larger sprite sheets and I would like to know what algorithms or techniques can be leveraged to increase the finding of sprites. A second implementation I considered, but have not tested yet, is to find the first pixel, then use a backtracking algorithm to find every connected pixel. This should find a contiguous sprite (breaks down if the sprite is something like an explosion where particles are no longer part of the main sprite). The cool thing is that I can immediately remove a detected sprite from the sprite sheet. Any other suggestions?

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  • Collision with half semi-circle

    - by heitortsergent
    I am trying to port a game I made using Flash/AS3, to the Windows Phone using C#/XNA 4.0. You can see it here: http://goo.gl/gzFiE In the flash version I used a pixel-perfect collision between meteors (it's a rectangle, and usually rotated) that spawn outside the screen, and move towards the center, and a shield in the center of the screen(which is half of a semi-circle, also rotated by the player), which made the meteor bounce back in the opposite direction it came from, when they collided. My goal now is to make the meteors bounce in different angles, depending on the position it collides with the shield (much like Pong, hitting the borders causes a change in the ball's angle). So, these are the 3 options I thought of: -Pixel-perfect collision (microsoft has a sample(http://create.msdn.com/en-US/education/catalog/tutorial/collision_2d_perpixel_transformed)) , but then I wouldn't know how to change the meteor angle after the collision -3 BoundingCircle's to represent the half semi-circle shield, but then I would have to somehow move them as I rotate the shield. -Farseer Physics. I could make a shape composed of 3 lines, and use that as the collision object for the shield. Is there any other way besides those? Which would be the best way to do it(it's aimed towards mobile devices, so pixel-perfect is probably not a good choice)? Most of the time there's always a easier/better way than what we think of...

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  • Confusion with floats converted into ints during collision detection

    - by TheBroodian
    So in designing a 2D platformer, I decided that I should be using a Vector2 to track the world location of my world objects to retain some sub-pixel precision for slow-moving objects and other such subtle nuances, yet representing their bodies with Rectangles, because as far as collision detection and resolution is concerned, I don't need sub-pixel precision. I thought that the following line of thought would work smoothly... Vector2 wrldLocation; Point WorldLocation; Rectangle collisionRectangle; public void Update(GameTime gameTime) { Vector2 moveAmount = velocity * (float)gameTime.ElapsedGameTime.TotalSeconds wrldLocation += moveAmount; WorldLocation = new Point((int)wrldLocation.X, (int)wrldLocation.Y); collisionRectangle = new Rectangle(WorldLocation.X, WorldLocation.Y, genericWidth, genericHeight); } and I guess in theory it sort of works, until I try to use it in conjunction with my collision detection, which works by using Rectangle.Offset() to project where collisionRectangle would supposedly end up after applying moveAmount to it, and if a collision is found, finding the intersection and subtracting the difference between the two intersecting sides to the given moveAmount, which would theoretically give a corrected moveAmount to apply to the object's world location that would prevent it from passing through walls and such. The issue here is that Rectangle.Offset() only accepts ints, and so I'm not really receiving an accurate adjustment to moveAmount for a Vector2. If I leave out wrldLocation from my previous example, and just use WorldLocation to keep track of my object's location, everything works smoothly, but then obviously if my object is being given velocities less than 1 pixel per update, then the velocity value may as well be 0, which I feel further down the line I may regret. Does anybody have any suggestions about how I might go about resolving this?

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  • Collision with half of a semi-circle

    - by heitortsergent
    I am trying to port a game I made using Flash/AS3, to the Windows Phone using C#/XNA 4.0. You can see it here: http://goo.gl/gzFiE In the flash version I used a pixel-perfect collision between meteors (it's a rectangle, and usually rotated) that spawn outside the screen, and move towards the center, and a shield in the center of the screen(which is half of a semi-circle, also rotated by the player), which made the meteor bounce back in the opposite direction it came from, when they collided. My goal now is to make the meteors bounce in different angles, depending on the position it collides with the shield (much like Pong, hitting the borders causes a change in the ball's angle). So, these are the 3 options I thought of: Pixel-perfect collision (Microsoft has a sample) , but then I wouldn't know how to change the meteor angle after the collision 3 BoundingCircle's to represent the half semi-circle shield, but then I would have to somehow move them as I rotate the shield. Farseer Physics. I could make a shape composed of 3 lines, and use that as the collision object for the shield. Is there any other way besides those? Which would be the best way to do it(it's aimed towards mobile devices, so pixel-perfect is probably not a good choice)? Most of the time there's always a easier/better way than what we think of...

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  • How to Create a Grid for a 2D Game?

    - by SoulBeaver
    So I'm currently writing the engine for my videogame. I've almost integrated Tiled (I think) so I should have a map-creator here soon. My question is, how do I actually make the grid? I'm really confused here. If I create a large map with, say, 20x20 grids the size of 32x32 (screen size 640x640), then what do I do with it? Let's say I have the code for creating a window, and then place a player sprite that I can move with input, that's fine. If I use one map that's as big as the screen, then every pixel on the map is also a pixel on the game screen. The mapping is exact. Now what happens if I have a 2000x2000 map, for example? My character would have to keep moving and move the map around (or rather the camera focused on the player moves). Then I can no longer say that the screen maps exactly to the pixel position of the map. I tried making a Grid class that maps out the screen area to 32x32 tiles, but I'm not sure if that makes any sense. Once the map moves each tile would have to update its information, or something. I'm just really confused here. How do I actually make the tiles and a grid and map them to the data I get from tiled, or that I make myself? Are there any good examples of source code that I could look at?

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  • Low framerate on background apps

    - by user1698923
    My problem is that when a game is running in the foreground, in Full Screen mode, any applications on my second monitor (such as youtube videos, videos, not app specific) drop their frame-rate to about 2-3 FPS. It seems like some sort of power management option that I can't track down. As far as I can tell, it's not due to the GPU not being able to keep up. For instance, my PC can play League of Legends at about 280FPS when the framerate is uncapped. If i cap it at 60FPS using the in-game option, it has no affect on the performance of the background app. Summary Operating System Windows 8 Pro 64-bit CPU Intel Core i7 3820 @ 3.60GHz 42 °C Sandy Bridge-E 32nm Technology RAM 12.0GB Triple-Channel DDR3 @ 533MHz (7-7-7-20) Motherboard Gigabyte Technology Co., Ltd. X79-UD3 (SOCKET 0) 37 °C Graphics DELL U2713HM (2560x1440@59Hz) DELL U2713HM (2560x1440@59Hz) 1280MB NVIDIA GeForce GTX 570 (Gigabyte) 58 °C Hard Drives 212GB Volume0 (RAID) 1863GB Western Digital WDC WD20EARS-00MVWB0 (SATA) 36 °C 1863GB Western Digital WDC WD20EARS-00MVWB0 (SATA) 34 °C Optical Drives No optical disk drives detected Audio ASUS Xonar Essence STX Audio Device Operating System Windows 8 Pro 64-bit Computer type: Desktop Graphics Monitor 1 Name DELL U2713HM on NVIDIA GeForce GTX 570 Current Resolution 2560x1440 pixels Work Resolution 2560x1400 pixels State Enabled, Output devices support Multiple displays Extended, Secondary, Enabled Monitor Width 2560 Monitor Height 1440 Monitor BPP 32 bits per pixel Monitor Frequency 59 Hz Device \\.\DISPLAY4\Monitor0 Monitor 2 Name DELL U2713HM on NVIDIA GeForce GTX 570 Current Resolution 2560x1440 pixels Work Resolution 2560x1400 pixels State Enabled, Output devices support Multiple displays Extended, Primary, Enabled Monitor Width 2560 Monitor Height 1440 Monitor BPP 32 bits per pixel Monitor Frequency 59 Hz Device \\.\DISPLAY5\Monitor0 NVIDIA GeForce GTX 570 Manufacturer NVIDIA Model GeForce GTX 570 GPU GF110 Device ID 10DE-1086 Revision A2 Subvendor Gigabyte (1458) Series GeForce GTX 500 Current Performance Level Level 3 Current GPU Clock 845 MHz Current Memory Clock 1900 MHz Current Shader Clock 1690 MHz Voltage 0.988 V Technology 40 nm Die Size 520 mm² Release Date Dec 07, 2010 DirectX Support 11.0 OpenGL Support 5.0 Bus Interface PCI Express x16 Temperature 57 °C Driver version 9.18.13.2018 BIOS Version 70.10.55.00.01 ROPs 40 Shaders 512 unified Memory Type GDDR5 Memory 1280 MB Bus Width 64x5 (320 bit) Filtering Modes 16x Anisotropic Noise Level Moderate Max Power Draw 219 Watts Count of performance levels : 3 Level 1 - "Default" GPU Clock 50 MHz Memory Clock 135 MHz Shader Clock 101 MHz Level 2 - "2D Desktop" GPU Clock 405 MHz Memory Clock 324 MHz Shader Clock 810 MHz Level 3 - "3D Applications" GPU Clock 845 MHz Memory Clock 1900 MHz Shader Clock 1690 MHz Things I've tried: 1) Updating the graphics driver 2) Setting windows power mode to High Performance 3) Reset Nvidia Global Performance settings to default

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  • Initialize preferences from XML in main Activity

    - by pixel
    My problem is that when I start application and user didn't open my PreferenceActivity so when I retrieve them don't get any default values defined in my preference.xml file. preference.xml file: <?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" android:key="applicationPreference" android:title="@string/config" > <ListPreference android:key="pref1" android:defaultValue="default" android:title="Title" android:summary="Summary" android:entries="@array/entry_names" android:entryValues="@array/entry_values" android:dialogTitle="@string/dialog_title" /> </PreferenceScreen> Snippet from my main Activity (onCreate method): SharedPreferences appPreferences = PreferenceManager.getDefaultSharedPreferences(this); String pref1 = appPreferences.getString("pref1", null); In result I end up with a null value.

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  • How to toggle orientation lock in android?

    - by pixel
    I want to create checkbox in my preference Activity that allows user to toggle orientation change. In similar questions people write only about complete orientation lock (by overriding onConfigurationChanged method or adding configChanges in AndroidManifest.xml) or orientation enforcing ( by setRequestedOrientation ). Is there a way to toggle orientation lock?

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  • Video playback on VideoView disappears after going back from another Activity

    - by pixel
    I have two Activities: one with VideoView and the second one. I start watching a video in the first Activity, then during playback I start second Activity. After going back to first Activity I can hear sound but see no picture. My Video Layout: <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <VideoView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:id="@+id/videoView" android:layout_gravity="center" /> <ListView android:layout_width="fill_parent" android:layout_height="125dp" android:id="@+id/ListView" /> </LinearLayout> Do you have any ideas why video doesn't appear?

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  • How to manage orientation lock in android?

    - by pixel
    I want to create checkbox in my preference Activity that allows user to toggle orientation change. In similar questions people write only about complete orientation lock (by overriding onConfigurationChanged method or adding configChanges in AndroidManifest.xml) or orientation enforcing ( by setRequestedOrientation ). Is there a way to toggle orientation lock?

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  • Redirect everything to index.php

    - by pixel
    I'm trying to do clean urls by exploding $_SERVER['REQUEST_URI'] and then switching between the results. However, once a user goes outside index.php, I'm assuming I need to redirect them back to index.php in order to process the URL they want to reach. How can I accomplish this? So for instance, user goes to www.domain.com/home/johndoe/... i'd like the index.php (domain.com/index.php) to be hit so that it can process the /home/johndoe/ via request_uri.

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