| '''OpenGL extension EXT.external_buffer |
| |
| This module customises the behaviour of the |
| OpenGL.raw.GLES2.EXT.external_buffer to provide a more |
| Python-friendly API |
| |
| Overview (from the spec) |
| |
| Extension EXT_buffer_storage introduced immutable storage buffers to |
| OpenGL ES. This extension allows the data store for an immutable buffer to |
| be sourced from an external EGLClientBuffer, allowing sharing of EGL client |
| buffers across APIs, across processes, and across different processing |
| cores such as the GPU, CPU, and DSP. |
| |
| Operations can then be performed on the external buffer using standard |
| GL buffer object procedures. The data in the allocation is not copied to |
| the buffer object's data store; the external allocation represents a single |
| memory allocation that can be shared across multiple GL objects -- this |
| aspect is similar to EGL external images. On the other hand, the external |
| buffer does not provide lifetime guarantees including orphaning and sibling |
| behavior as provided by EGL external images. |
| |
| The EGLClientBuffer must be allocated in a way which permits this shared |
| access. For example, on Android via a shareable Android hardware buffer. |
| This extension does not enable support for arbitrary EGLClientBuffers to be |
| used as an external buffer. |
| |
| It is the application's responsibility to ensure synchronization between |
| operations performed by separate components (DSP / CPU / GPU) and processes |
| on the external buffer. Additionally the application is responsible for |
| avoiding violating existing GL spec requirements. For example, mapping a |
| single shared allocation to two GL buffer objects and then performing |
| CopyBufferSubData such that the read and write regions overlap would |
| violate the existing CopyBufferSubData spec regarding copies performed |
| with the same buffer set for source and destination. |
| |
| The application must take any steps necessary to ensure memory access to |
| the external buffer behaves as required by the application. For example, |
| preventing compilation differences in data padding from causing data to be |
| inadvertently corrupted by using defined structure alignment methods such |
| as the std140 layout qualifier. The application is responsible for |
| managing the lifetime of the external buffer, ensuring that the external |
| buffer is not deleted as long as there are any GL buffer objects referring |
| to it. |
| |
| The official definition of this extension is available here: |
| http://www.opengl.org/registry/specs/EXT/external_buffer.txt |
| ''' |
| from OpenGL import platform, constant, arrays |
| from OpenGL import extensions, wrapper |
| import ctypes |
| from OpenGL.raw.GLES2 import _types, _glgets |
| from OpenGL.raw.GLES2.EXT.external_buffer import * |
| from OpenGL.raw.GLES2.EXT.external_buffer import _EXTENSION_NAME |
|
|
| def glInitExternalBufferEXT(): |
| '''Return boolean indicating whether this extension is available''' |
| from OpenGL import extensions |
| return extensions.hasGLExtension( _EXTENSION_NAME ) |
|
|
|
|
| |
