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Thread: OpenGL ES Performance on MX31

  1. #1

    OpenGL ES Performance on MX31

    Hi,

    On comparing the performance of
    1) drawing a texture quad to a native display (glTexSubImage+glDrawArrays+eglSwapBuffers)

    to

    2) Drawing a pixel buffer directly to the framebuffer without using any opengles

    there was a VERY noticable difference. The direct draw to framebuffer was 3 times faster. Is there any way to tweak and optimize (1). What could be the cause of delay? Does a texture upload involve some inter process communication?

    Thanks for your help.

  2. #2
    Senior Member
    Join Date
    May 2006
    Posts
    353
    How do you measure the time? What size is the rectangle you're copying to the screen?

    It's extremely unlikely that the first method would be faster than the second, since it involves at least two copies: glTexSubImage copies from application memory to texture memory, and the renderer reads from texture memory and writes to the frame buffer.

    In addition, texture upload is not just a straight copy. The texture data gets reformatted to optimize memory access patterns.

    Why exactly are you using OpenGL ES?
    Georg Kolling, Imagination Technologies
    Please ask questions specific to PowerVR hardware or SDKs on the PowerVR Insider Forum
    DevTech@imgtec.com | http://www.powervrinsider.com

  3. #3
    How do you measure the time?
    In ms.. using a tick count i suppose

    What size is the rectangle you're copying to the screen?
    800x480

    It's extremely unlikely that the first method would be faster than the second
    I understand, but I dont think it should be three times(ogles texture upload(glSub2D+glDrawArrays+eglSwapBuffers)-150ms, memcpy to framebuffer-50ms).

    The texture data gets reformatted to optimize memory access patterns.
    What can we do to minimize the processing here?

    Why exactly are you using OpenGL ES?
    Fast and complicated animations on an ARM device.

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