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Member Since 10 Jul 2009
Offline Last Active Today, 10:38 AM

Topics I've Started

How to retrieve P-States?

19 August 2011 - 02:48 PM

Does anyone know how performance states (P-States) available on the particular GPU can be retrieved, and what is the current P-State?

I bet NVAPI can do that (of course for NV cards only), but the appropriate API is not published. NvAPI_GPU_GetDynamicPstatesInfoEx() retrieves only utilization (hidden function NvAPI_GPU_GetPStates does the same). I can get all current frequencies, but how to recognize which P-State they belong?

Thank you in advance!

How to change VBO by content of another?

28 January 2011 - 05:56 PM

Hi All,

In order to avoid unnecessary stress caused by walking an unknown path, I would rather ask the community to help me answer the following question:

How to change the content of one VBO by content of the other using OpenGL API?

It is not an ordinary copying. For example, I need to create an upsampled/downsampled version of data already stored in another VBO, or something similar. I have implemented it using CUDA, but that approach has several drawbacks:

1. The registering process (cudaGraphicsGLRegisterBuffer) is a pretty lengthy operation. Application initialization time becomes unacceptably long if I register all VBOs I want to use later.

2. Whenever a transformation should occur, buffers involved in the transformation have to be mapped (cudaGraphicsMapResources + cudaGraphicsResourceGetMappedPointer). Mapping requires all pending GL calls to finish before CUDA start to use the resources.

3. Unmapping (cudaGraphicsUnmapResources) also creates a stall in a pipeline waiting CUDA to finish all pending calls.

Much of the Map/Unmap times can be hidden by smart code reorganization, but cannot be completely eliminated. Application initialization (registering) is the most irritating issue. There are also other issues, but I believe they are driver dependent, and they currently make no trouble (like different VBO memory footprints after mapping with CUDA). Having all previously mentioned in mind I would try to use only GL API to achieve similar results, and to avoid stalls imposed by CUDA/GL interoperability.

Before starting banging my head against the wall, I would like to hear your opinions and suggestions.

Thank you in advance!

Projection matrix for non-constant FOV

26 January 2011 - 11:07 AM

Could anyone help me to derive a projection matrix that enables linear change of vertical FOV from left to right?

The problem I'm trying to solve is a projection onto the screen that is not perpendicular to a view direction. Furthermore, there are a lot of such screens that have to be aligned. Thus far I've been using averaged FOV, but the results are not adequate.

Thank you in advance!