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Thread: glDrawTex - a hardware blitter?

  1. #1
    Junior Member
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    glDrawTex - a hardware blitter?

    Hello,

    I'm pretty new to OpenGL. I'd like to know this, since its not mentioned explicitly in the documentation:

    Does glDrawTex acts as a hardware blitter for the back buffer, or just as a simple "create 2 triangles, UV them, and send' em to the pipeline".

    Personally/IMO, I expect its some kind of HW shortcut for the last thing, since I can specify the Z for the rectangle, so it probably keeps and sorts them all.

    Thanks in advance!

    PS: My target device is a Nokia N95 @ PoweVR MBX + that V-somethign extra accelerator thingy (probably hw T&L or so, don't remember exactly)

  2. #2
    Senior Member
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    Re: glDrawTex - a hardware blitter?

    Quote Originally Posted by raicuandi
    I'm pretty new to OpenGL. I'd like to know this, since its not mentioned explicitly in the documentation:

    Does glDrawTex acts as a hardware blitter for the back buffer, or just as a simple "create 2 triangles, UV them, and send' em to the pipeline".
    On PowerVR MBX it is implemented as two triangles. However I'm not sure why you ask this question. Regardless of how it is implemented, rendering behaviour should be the same, since that is what the spec dictates.

    PS: My target device is a Nokia N95 @ PoweVR MBX + that V-somethign extra accelerator thingy (probably hw T&L or so, don't remember exactly)
    PowerVR VGP, and yes, it's hardware T&L (and more flexible vertex shading, which is not exposed on any Nokia device).
    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
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    Thanks! I'll run some performance tests and see how it goes

    /edit:
    Sorry I was unclear. I was asking performance-wise: if glDrawTex is fast enough to draw lots of stuff. (ie: 2D GUI over 3D scene)

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