When utilizing [AWT]GLReadBufferUtil it is usually desired to read from the front-buffer instead the back-buffer. The latter may not be defined, e.g. when using MSAA. A GLEventListener utilizing [AWT]GLReadBufferUtil, must perform the drawable.swapBuffers() to be able to read from the front-buffer. Usually GLAutoDrawable.setAutoSwapBuffer(false) should be called here, to avoid a double swap - however GLJPanel does not support toggling auto-swap since it requires to control swap for it's own read-pixels. Remedy for GLJPanel: - GLJPanel issues helper.setAutoSwapBufferMode(false) - immutable - Enable GLJPanel.swapBuffer() if initializes This was previously disabled. - GLJPanel's OffscreenBackend listens to surfaceUpdated, to be notified whether postGL needs to swap buffer or the drawable.swapBuffer() was already called between preGL and postGL. See unit tests adding/removing a snapshot GLEventListener performing swapBuffers() and setting auto-swap accordingly.
908ebd99d1eb57ce773a1fdd67c76886da86b9e6 fixed as described
82f679b064784213591b460fc5eaa1f5f196fbd1 GLJPanel: Use default auto-swap mechanims Refines commit 908ebd99d1eb57ce773a1fdd67c76886da86b9e6 Note that the test case decide whether to auto-swap (after read-pixels) or not auto-swap (manual swap before read-pixels). See UITestCase.swapBuffersBeforeRead(GLCapabilitiesImmutable chosenCaps): Determines whether the chosen GLCapabilitiesImmutable requires a swap-buffers before reading pixels. Usually one uses the default-read-buffer, i.e. GL.GL_FRONT for single-buffer and GL.GL_BACK for double-buffer GLDrawables and GL.GL_COLOR_ATTACHMENT0 for offscreen framebuffer objects. Here swap-buffers shall happen after calling reading pixels, the default. However, multisampling offscreen GLFBODrawables utilize swap-buffers to downsample the multisamples into the readable sampling sink. In this case, we require a swap-buffers before reading pixels. Returns: chosenCaps.isFBO() && chosenCaps.getSampleBuffers() +++ +++ - GLJPanel: - Remove SurfaceUpdatedListener mechanism in favor of default auto-swap-buffer via GLDrawableHelper. This removes complexity. - postGL does not need to perform explicit swapBuffer operation, but rely on GLDrawableHelper and the default mechanism. This is also compatible w/ J2D backend. - Use GLDrawableHelper for setAutoSwapBufferMode(..) and getAutoSwapBufferMode() +++ UnitTests: - UITestCase: - Add 'boolean swapBuffersBeforeRead(GLCapabilitiesImmutable chosenCaps)' to determine whether swapBuffers() must occure before read-pixels. See above. - GLReadBuffer00Base* - remove explicit addSnapshotGLEL/removeSnapshotGLEL - add TextRendererGLEL, to display frame-count and -dimension - SnapshotGLEL* - simply toggle auto-swap in their init(..) and dispose(..) method! - clear back-buffer if 'swapBuffersBeforeRead' to test whether the right buffer is being used for read-pixels.
d46d9ad8f998a7128d9f023294d5f489673d6d8a Bug 975 - GLJPanel's OffscreenDrawable shall not double swap - Refine unit test for visual validation of 'no frame lag' To validate whether a 'display' command w/o animator results to the desired frame we introduce a 'userCounter' in TextRendererGLEL. The latter gets increased and maybe visually validated by a key-press -> display. Results: In all modes, MSAA or !MSAA, or flip - the result is valid. Tested on windows and linux.
41190c3830157abdf9649cbf7767e57108f55075 Fix auto-swap mechanism ; Refined API doc getDefaultReadBuffer() ; Add GLDrawableUtil.swapBuffersBeforeRead Commit 82f679b064784213591b460fc5eaa1f5f196fbd1 which introduces the default swap-buffers mechanism is erroneous: The OffscreenBack backend requires the following operation order: Order-1: [1] - GL display [2] - GL swapBuffers (always due to single-buffer non-MSAA or MSAA offscreen drawable) [3] - readPixels +++ Commit 82f679b064784213591b460fc5eaa1f5f196fbd1 however introduced: Order-2: [a] - GL display [b] - readPixels [c] - GL swapBuffers (always due to single-buffer non-MSAA or MSAA offscreen drawable) since [a] and [b] happened in Updater's display method, and [c] followed the same triggered by GLAutoDrawableHelper. +++ The proof, commit d46d9ad8f998a7128d9f023294d5f489673d6d8a, is faulty, since it always included the 'snapshot' GL event listener which turned-off auto-swap and swapped before read-pixels. TL;DR it enforced proper Order-1. +++ This fix allows the Backend to intercept disable GLDrawableHelper's setAutoSwapBufferMode(..) and perform the auto-swap mode itself in the proper Order-1. The unit test has been refined to optionally disable the snapshot to validate auto-swap mode. +++ Refined GLBase and GLContext's API doc for 'getDefaultReadBuffer()' +++ Add GLDrawableUtil.swapBuffersBeforeRead(..) and reuse it for TileRendererBase (original impl.).
b96fc594f15fcf9ee0fd238ce8d7a10aea781d32 GLContextImpl/GLDrawableImpl.getDefaultReadBuffer(..): Pass hint whether dedicated read-drawable is being used (double buffering)
Also related Bug 941 and Bug 1020
Test cases: com.jogamp.opengl.test.junit.jogl.acore.TestGLReadBuffer01GLJPanelAWT com.jogamp.opengl.test.junit.jogl.acore.TestGLReadBuffer01GLCanvasAWT com.jogamp.opengl.test.junit.jogl.acore.TestGLReadBuffer01GLWindowNEWT