| '''OpenGL extension NV.gpu_affinity |
| |
| This module customises the behaviour of the |
| OpenGL.raw.WGL.NV.gpu_affinity to provide a more |
| Python-friendly API |
| |
| Overview (from the spec) |
| |
| On systems with more than one GPU it is desirable to be able to |
| select which GPU(s) in the system become the target for OpenGL |
| rendering commands. This extension introduces the concept of a GPU |
| affinity mask. OpenGL rendering commands are directed to the |
| GPU(s) specified by the affinity mask. GPU affinity is immutable. |
| Once set, it cannot be changed. |
| |
| This extension also introduces the concept called affinity-DC. An |
| affinity-DC is a device context with a GPU affinity mask embedded |
| in it. This restricts the device context to only allow OpenGL |
| commands to be sent to the GPU(s) in the affinity mask. |
| |
| Handles for the GPUs present in a system are enumerated with the |
| command wglEnumGpusNV. An affinity-DC is created by calling |
| wglCreateAffinityDCNV. This function takes a list of GPU handles, |
| which make up the affinity mask. An affinity-DC can also |
| indirectly be created by obtaining a DC from a pBuffer handle, by |
| calling wglGetPbufferDC, which in turn was created from an |
| affinity-DC by calling wglCreatePbuffer. |
| |
| A context created from an affinity DC will inherit the GPU |
| affinity mask from the DC. Once inherited, it cannot be changed. |
| Such a context is called an affinity-context. This restricts the |
| affinity-context to only allow OpenGL commands to be sent to those |
| GPU(s) in its affinity mask. Once created, this context can be |
| used in two ways: |
| |
| 1. Make the affinity-context current to an affinity-DC. This |
| will only succeed if the context's affinity mask is the same |
| as the affinity mask in the DC. There is no window |
| associated with an affinity DC, therefore this is a way to |
| achieve off-screen rendering to an OpenGL context. This can |
| either be rendering to a pBuffer, or an application created |
| framebuffer object. In the former case, the affinity-mask of |
| the pBuffer DC, which is obtained from a pBuffer handle, |
| will be the same affinity-mask as the DC used to created the |
| pBuffer handle. In the latter case, the default framebuffer |
| object will be incomplete because there is no window-system |
| created framebuffer. Therefore, the application will have to |
| create and bind a framebuffer object as the target for |
| rendering. |
| 2. Make the affinity-context current to a DC obtained from a |
| window. Rendering only happens to the sub rectangles(s) of |
| the window that overlap the parts of the desktop that are |
| displayed by the GPU(s) in the affinity mask of the context. |
| |
| Sharing OpenGL objects between affinity-contexts, by calling |
| wglShareLists, will only succeed if the contexts have identical |
| affinity masks. |
| |
| It is not possible to make a regular context (one without an |
| affinity mask) current to an affinity-DC. This would mean a way |
| for a context to inherit affinity information, which makes the |
| context affinity mutable, which is counter to the premise of this |
| extension. |
| |
| The official definition of this extension is available here: |
| http://www.opengl.org/registry/specs/NV/gpu_affinity.txt |
| ''' |
| from OpenGL import platform, constant, arrays |
| from OpenGL import extensions, wrapper |
| import ctypes |
| from OpenGL.raw.WGL import _types, _glgets |
| from OpenGL.raw.WGL.NV.gpu_affinity import * |
| from OpenGL.raw.WGL.NV.gpu_affinity import _EXTENSION_NAME |
|
|
| def glInitGpuAffinityNV(): |
| '''Return boolean indicating whether this extension is available''' |
| from OpenGL import extensions |
| return extensions.hasGLExtension( _EXTENSION_NAME ) |
|
|
|
|
| |
