glreadpixels

问题 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

问题 I need to create a HBITMAP from data returned by a glReadPixels() call: HDC hCompDC = CreateCompatibleDC(NULL); HDC hDC = GetDC(); m_hClipboardBitmap = CreateCompatibleBitmap(hDC, size.cx, size.cy); if ( m_hClipboardBitmap == NULL ) { throw runtime_error( "Unable to create bitmap." ); } HBITMAP hOldBm = (HBITMAP) SelectObject( hCompDC, m_hClipboardBitmap ); int numberOfBytes = 4 * size.cx * size.cy; unsigned char *pPixelData = new unsigned char[numberOfBytes]; ::glReadPixels(minimum.x,

问题 I am currently working with ARCore to classify images and put objects on the images. But it seems like ARCore camera doesn't provide any way to get the pixelbuffer. then i came accross How to take picture with camera using ARCore and according this we can copy the frame from OpenGL using GLES20.glReadPixels . if i pass each frame at a time my classifier works fine but when i put GLES20.glReadPixels to get the pixel buffer in a separate thread i am getting all zeros. so basically it gives me

问题 I am currently working with ARCore to classify images and put objects on the images. But it seems like ARCore camera doesn't provide any way to get the pixelbuffer. then i came accross How to take picture with camera using ARCore and according this we can copy the frame from OpenGL using GLES20.glReadPixels . if i pass each frame at a time my classifier works fine but when i put GLES20.glReadPixels to get the pixel buffer in a separate thread i am getting all zeros. so basically it gives me

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Why is glReadPixels() failing in this code in iOS 6.0? I currently have an App in Appstore that uses the Cocos2D framework. For collision detection I am using glReadPixels. The screen only has white and black pixels and detecting a black pixel means collision. Everything works fine up to iOS 5.1.1 but in iOS6 Beta (all of them) glReadPixels stopped working. Now the RGB values returned by glReadPixels are always

问题 You know the sample code of Apple with the CameraRipple effect? Well I'm trying to record the camera output in a file after openGL has done all the cool effect of water. I've done it with glReadPixels, where I read all the pixels in a void * buffer , create CVPixelBufferRef and append it to the AVAssetWriterInputPixelBufferAdaptor, but it's too slow, coz readPixels takes tons of time. I found out that using FBO and texture cash you can do the same, but faster. Here is my code in drawInRect

问题 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

问题 How do I flip an Screenshot image? I can't find my problem anywhere else. Example code: /* *@param fileLoc //Location of fileoutput destination *@param format //"png" *@param WIDTH //Display.width(); *@param HEIGHT //Display.height(); */ private void getScreenImage(){ int[] pixels = new int[WIDTH * HEIGHT]; int bindex; // allocate space for RBG pixels ByteBuffer fb = ByteBuffer.allocateDirect(WIDTH * HEIGHT * 3);//.order(ByteOrder.nativeOrder()); // grab a copy of the current frame contents

问题 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,

问题 I'm working on an Augmented Reality app for a client. The OpenGL and EAGL part has been done in Unity 3D, and implemented into a View in my application. What i need now, is a button that snaps a screenshot of the OpenGL content, which is the backmost view. I tried writing it myself, but when i click a button with the assigned IBAction, it only saves 1/4 of the screen (the lower left corner) - though it does save it to the camera roll. So basically, how can i make it save the entire screensize