OpenGL.GL.NV.transform_feedback

OpenGL extension NV.transform_feedback

This module customises the behaviour of the OpenGL.raw.GL.NV.transform_feedback to provide a more Python-friendly API

Overview (from the spec)

This extension provides a new mode to the GL, called transform feedback, which records vertex attributes of the primitives processed by the GL. The selected attributes are written into buffer objects, and can be written with each attribute in a separate buffer object or with all attributes interleaved into a single buffer object. If a geometry program or shader is active, the primitives recorded are those emitted by the geometry program. Otherwise, transform feedback captures primitives whose vertex are transformed by a vertex program or shader, or by fixed-function vertex processing. In either case, the primitives captured are those generated prior to clipping. Transform feedback mode is capable of capturing transformed vertex data generated by fixed-function vertex processing, outputs from assembly vertex or geometry programs, or varying variables emitted from GLSL vertex or geometry shaders.

The vertex data recorded in transform feedback mode is stored into buffer objects as an array of vertex attributes. The regular representation and the use of buffer objects allows the recorded data to be processed directly by the GL without requiring CPU intervention to copy data. In particular, transform feedback data can be used for vertex arrays (via vertex buffer objects), as the source for pixel data (via pixel buffer objects), as program constant data (via the NV_parameter_buffer_object or EXT_bindable_uniform extension), or via any other extension that makes use of buffer objects.

This extension introduces new query object support to allow transform feedback mode to operate asynchronously. Query objects allow applications to determine when transform feedback results are complete, as well as the number of primitives processed and written back to buffer objects while in transform feedback mode. This extension also provides a new rasterizer discard enable, which allows applications to use transform feedback to capture vertex attributes without rendering anything.

The official definition of this extension is available here: http://www.opengl.org/registry/specs/NV/transform_feedback.txt