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javaopengllwjglglreadpixelspbo

LWJGL Using PBO for reading pixels fail

I'm trying to read from the framebuffer Asynchronously but glReadPixels() generates an INVALID_OPERATION error.

I've read what might cause this error but i haven't found any problem in my code: 

 int PBOHandle = glGenBuffers(); // PBOHandle != 0
 int Width = Display.getDisplayMode().getWidth(); // 800
 int Height = Display.getDisplayMode().getHeight();// 600
 glReadBuffer(GL_FRONT);
 glBindBuffer(GL_PIXEL_PACK_BUFFER, PBOHandle);
 glReadPixels(0, 0, Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, 0);
 // GL_INVALID_OPERATION right here
 glBindBuffer(GL_PIXEL_PACK_BUFFER, PBOHandle);
 ByteBuffer Buffer = glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_WRITE, null);
 /* stuff */
 glUnmapBuffer(GL_PIXEL_PACK_BUFFER);
 glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
Solution

  • You did not properly create a real pixel buffer object. All you did was creating a name for one. You must call glBufferData() to create an actual data store. Use NULL as the data pointer to create an unitizialized buffer.