| '''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 |
| ) |
| |
