NVIDIA Internal Format Query 2 oddness

I’m using NVIDIA’s 310.90 drivers on a GeForce GT250. And I’m testing out ARB_internalformat_query2, to see what you get when you try different things.

One oddity is that basic image formats like GL_RGBA8 will, when queried with GL_READ_PIXELS, return GL_NO_SUPPORT. This means that it should not be possible to use glReadPixels on FBOs with such formats bound. This seems… unlikely. Especially as I tried it with texture targets GL_TEXTURE_2D and GL_RENDERBUFFER.

Because the operation is unsupported, I also got GL_NONE for GL_READ_PIXEL_FORMAT.

Also, I got GL_NONE for the TEXTURE_IMAGE_FORMAT and GET_TEXTURE_IMAGE_FORMAT. Oddly enough, the _TYPE versions return real values.

On my 580I get


    glGetInternalformativ(GL_TEXTURE_2D,GL_RGBA8,GL_READ_PIXELS,1,buffers);

FULL_SUPPORT    

  glGetInternalformativ(GL_TEXTURE_2D,GL_RGBA8,GL_READ_PIXELS_FORMAT,1,buffers);

0x1908

    glGetInternalformativ(GL_TEXTURE_2D,GL_RGBA8,GL_TEXTURE_IMAGE_FORMAT,1,buffers);

0x1908


I don’t know what 0x1908 is.

0x1908 = GL_RGBA

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