glreadpixels

I want to use two PBOs to read pixel in alternative way. I thought the PBO way will much faster, because glReadPixels returns immediately when using PBO, and a lot of time can be overlapped. Strangely there seems to be not much benefit. Considering some code like: glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, 0); Timer t; t.start(); glReadPixels(0,0,1024,1024,GL_RGBA, GL_UNSIGNED_BYTE, buf); t.stop(); std::cout << t.getElapsedTimeInMilliSec() << " "; glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, pbo); t.start(); glReadPixels(0,0,1024,1024,GL_RGBA, GL_UNSIGNED_BYTE, 0); t.stop(); std::cout << t

hey i m trying the record the gameplay of my game so that i can upload its video to youtube from device itself...m trying to do same thing as Talking tomcat app for iphone..recording the video then playing it ,etc... i m using glReadPixels() for reading framebuffer data and then writing it to video with the help of AVAssetWriter in AVFoundation framwork. But reading the data on each drawing decreases the FPS from around 30-35 to 2-3 only while using glReadPixels. i think Talking tomcat is also made with the help of Opengl ES it also has the video recording facility but it doesnot slows down

Can I use Pixel Buffer Object (PBO) to directly read the pixels values (i.e. using glReadPixels) from the FBO (i.e. while FBO is still attached)? If yes, What are the advantages and disadvantages of using PBO with FBO? What is the problem with following code { //DATA_SIZE = WIDTH * HEIGHT * 3 (BECAUSE I AM USING 3 CHANNELS ONLY) // FBO and PBO status is good . . glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fboId); //Draw the objects Following glReadPixels works fine glReadPixels(0, 0, screenWidth, screenHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, (uchar*)cvimg->imageData); Following glReadPixels DOES

I want to dump raw texture data to disk (to read back later), and I'm not sure about glReadPixel will read from the currently bound texture. How can I read the buffer from my texture? glReadPixels function reads from framebuffers, not textures. To read a texture object you must use glGetTexImage but it isn't available in OpenGL ES :( If you want to read the buffer from your texture then you can bind it to an FBO (FrameBuffer Object) and use glReadPixels : //Generate a new FBO. It will contain your texture. glGenFramebuffersOES(1, &offscreen_framebuffer); glBindFramebufferOES(GL_FRAMEBUFFER_OES

How to take a screenshot of an OpenGL window in C++ and save it to file. I found the glReadPixels() function, but I don't know what to do next. Where I can set path to a file, for example? If not difficult, write code, please. huy This piece of code captures the OpenGL window and export to a BMP file. You must have FreeImage library to run it. // Make the BYTE array, factor of 3 because it's RBG. BYTE* pixels = new BYTE[3 * width * height]; glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels); // Convert to FreeImage format & save to file FIBITMAP* image = FreeImage

I want to get every OpenGL frame from an animation with glReadPixels() and convert the data to OpenCV::Mat . I know that glReadPixels() gets the data by rows from the lower one to upper one, from left to right. On the other hand, OpenCV stores the data differently. Does anybody know any library or any tutorial/example that helps me to convert data from glReadPixels to a OpenCV:Mat in C++? SUMMARY OpenGL frame -----------------------> CV::Mat Data from left to right, Data from left to right, bottom to top. top to bottom. First we create an empty (or unititialized) cv::Mat for our data to be