glFlushMappedBufferRange

glFlushMappedBufferRange is an OpenGL API function used to flush a previously mapped range of a buffer object's data store back to the graphics pipeline. It ensures that writes performed by the client into a mapped buffer are made visible to the GL driver and to subsequent GL operations. The function is part of the buffer-mapping feature set introduced by the ARB_map_buffer_range extension and is commonly used with glMapBufferRange and persistent mappings.

Syntax: void glFlushMappedBufferRange(GLenum target, GLintptr offset, GLsizeiptr length);

Parameters:

- target: the binding target of the buffer object whose data store is mapped (for example GL_ARRAY_BUFFER or GL_ELEMENT_ARRAY_BUFFER). The active binding determines which buffer is affected.

- offset: the starting byte offset into the buffer’s data store for the range to flush.

- length: the size, in bytes, of the range to flush.

Behavior: The function flushes the specified range of the mapped memory so future GL operations see the latest client-side writes. If the range is not currently mapped or outside the mapped region, an error (GL_INVALID_OPERATION) may be generated. When a mapping is coherent or not persistent, the flush may be a no-op.

Usage notes: Use glFlushMappedBufferRange when writing to a buffer via a mapped pointer obtained from glMapBufferRange with write access, especially when using persistent mappings. It is often paired with glUnmapBuffer when done, or used to flush only sub-ranges to minimize overhead. See also glMapBufferRange, glMapBuffer, glUnmapBuffer and GL_ARB_map_buffer_range.