| | '''OpenGL extension NV.fence |
| | |
| | This module customises the behaviour of the |
| | OpenGL.raw.GL.NV.fence to provide a more |
| | Python-friendly API |
| | |
| | Overview (from the spec) |
| | |
| | The goal of this extension is provide a finer granularity of |
| | synchronizing GL command completion than offered by standard OpenGL, |
| | which offers only two mechanisms for synchronization: Flush and Finish. |
| | Since Flush merely assures the user that the commands complete in a |
| | finite (though undetermined) amount of time, it is, thus, of only |
| | modest utility. Finish, on the other hand, stalls CPU execution |
| | until all pending GL commands have completed. This extension offers |
| | a middle ground - the ability to "finish" a subset of the command |
| | stream, and the ability to determine whether a given command has |
| | completed or not. |
| | |
| | This extension introduces the concept of a "fence" to the OpenGL |
| | command stream. Once the fence is inserted into the command stream, it |
| | can be queried for a given condition - typically, its completion. |
| | Moreover, the application may also request a partial Finish -- that is, |
| | all commands prior to the fence will be forced to complete until control |
| | is returned to the calling process. These new mechanisms allow for |
| | synchronization between the host CPU and the GPU, which may be accessing |
| | the same resources (typically memory). |
| | |
| | This extension is useful in conjunction with NV_vertex_array_range |
| | to determine when vertex information has been pulled from the |
| | vertex array range. Once a fence has been tested TRUE or finished, |
| | all vertex indices issued before the fence must have been pulled. |
| | This ensures that the vertex data memory corresponding to the issued |
| | vertex indices can be safely modified (assuming no other outstanding |
| | vertex indices are issued subsequent to the fence). |
| | |
| | The official definition of this extension is available here: |
| | http://www.opengl.org/registry/specs/NV/fence.txt |
| | ''' |
| | from OpenGL import platform, constant, arrays |
| | from OpenGL import extensions, wrapper |
| | import ctypes |
| | from OpenGL.raw.GL import _types, _glgets |
| | from OpenGL.raw.GL.NV.fence import * |
| | from OpenGL.raw.GL.NV.fence import _EXTENSION_NAME |
| |
|
| | def glInitFenceNV(): |
| | '''Return boolean indicating whether this extension is available''' |
| | from OpenGL import extensions |
| | return extensions.hasGLExtension( _EXTENSION_NAME ) |
| |
|
| | |
| | glDeleteFencesNV=wrapper.wrapper(glDeleteFencesNV).setInputArraySize( |
| | 'fences', None |
| | ) |
| | glGenFencesNV=wrapper.wrapper(glGenFencesNV).setOutput( |
| | 'fences',size=lambda x:(x,),pnameArg='n',orPassIn=True |
| | ) |
| | glGetFenceivNV=wrapper.wrapper(glGetFenceivNV).setOutput( |
| | 'params',size=_glgets._glget_size_mapping,pnameArg='pname',orPassIn=True |
| | ) |
| | |