Is this an optix bug about opengl interop?

In the toturial of sdk sample, I change part of tutorial0.cu as follows:
I add :

if (launch_index.y < 10)
  {
	  output_buffer[launch_index] = make_color(make_float3(1, 0, 0));
  }
else

before

output_buffer[launch_index] = make_color( prd.result );

I except there red lines on the top of the rusult image, but, on the controry, the red lines is showed on the bottom of the image.
When I use the D3D to interop with optix, th result is normal,i.e.,the red line on the top.
I guess opengl and d3d have different way to handle resource, am I right?

OpenGL textures have their origin at the bottom left, D3D at the top left.
A standard pinhole camera which renders the bottom left corner into launch index (0, 0) will be upright when loaded into an OpenGL texture.
Just adapt your ray generation to render the top left corner into launch index 0,0 and it should match D3D’s texture origin placement or flip your texture coordinates when displaying it to the screen.

I see, the origin of rtBuffer is at the bottom left! Thanks!