depth texture on PowerVR SGX540

This topic contains 3 replies, has 2 voices, and was last updated by  Deep 4 years, 7 months ago.

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  • #31181

    Deep
    Member

    I’ve got an application that renders the color and depth buffers to textures via a frame buffer object using OpenGL ES 2.0. Using the PC Emulator everything works fine, but when I try to run the application on the actual hardware (PowerVR SGX540), the color texture is valid, but the depth texture appears to be all black. I don’t appear to be getting any OpenGL or driver errors, but it appears that no data is being written to the depth texture. I’m using GL_DEPTH_COMPONENT for the depth texture format and GL_UNSIGNED_SHORT for the type.

    Is there any reason this configuration wouldn’t work on the SGX540? Does anyone know of anything I need to look out for in trying to make this work?

    #36828

    Deep
    Member

    Please disregard, I figured it out. Oddly enough, it was the depth texture wrapping mode. Changing this from GL_REPEAT to GL_CLAMP_TO_EDGE fixed the problem. Go figure.

    #36829

    chris
    Moderator

    The reason for this is that non-power-of-two textures are only partially supported in OpenGL ES and the emulator is not currently imitating the hardware correctly. Specifically, a black texture should be produced for NPOT textures if:

    – GL_TEXTURE_MIN_FILTER is set to anything other than GL_NEAREST or GL_LINEAR
    – The repeat mode is set to anything other than GL_CLAMP_TO_EDGE

    If you’d like to use a wrapping texture then the dimensions of your texture should be powers of two.

    #36830

    Deep
    Member

    Thanks for the explanation. However, my texture size was 512×512. Is it possible that these restrictions apply even for non-power of two textures?

    The wrap mode was originally set to GL_REPEAT by accident, so using GL_CLAMP_TO_EDGE is fine for me.

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