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Thread: buffer usage while mapped

  1. #1
    Junior Member Newbie
    Join Date
    Apr 2013

    buffer usage while mapped


    I like to see a flag for glMapBufferRange that will allow the usage of this buffer while mapped. The use case will be almost the same as for AMD_pinned_memory (streaming buffers without overhead) but with less pitfalls imo.
    The main difference to AMD_pinned_memory is the implicit memory mangement.

    Solved AMD_pinned_memory pitfalls:
    - OS dependent alignment done by driver
    - Usage after free: The pointer will be invalid after the glUnmap call and the memory will be deleted when it isn't needed any more by GL. glFinish isn't needed any more
    - No dependencies to other drivers which may also do magic on this memory block

    New issues:
    - Current content has to be read back to cpu ram without GL_MAP_INVALIDATE_BUFFER_BIT, also with GL_MAP_INVALIDATE_RANGE_BIT.
    -> Only done once in initialization
    - Using of cpu memory is slow
    -> Should only be used for streaming. So PCI-E is always the bottleneck


  2. #2
    Junior Member Newbie
    Join Date
    Apr 2013
    Something like this was added to OpenGL 4.4: ARB_buffer_storage

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