Occlusion querries

Discussion created by lpw on Sep 22, 2008
Latest reply on Jul 8, 2009 by lipi

Hi all,

Is there currently any way to issue occlusion queries that will work with CAL? The idea is to count the number of pixels that actually make it to the "framebuffer," i.e. are not discarded by the pixel shader (a CAL program). This technique is very common in the GPGPU world.

I can do occlusion queries with OpenGL or DirectX alone, as long as I don't use double precision. Unfortunately, the project I'm working on requires double precision, so the graphics APIs are of no use (the very reason I switched to CAL in the first place).

I see three possible ways in which occlusion query support could be achieved:

1) Use the CAL <--> D3D interoperability extension. Associate a CAL device with a D3D device. Do everything using CAL, but inject some query markers using the D3D device interface. Unfortunately, the interoperability extension does not appear to work at all at this point (a topic for another thread).

2) Do everything in D3D (or OpenGL), but compile a kernel using an AMD compiler. I'm not sure how to go about this or if it's even possible.

3) Doing occlusion querries via an interface similar to the current counter extensions would be nice to have in the future. Is there any hope?

Could someone from AMD comment on this or suggest a solution? (Of course, comments and suggestions are welcome from fellow users as well!)