GLMAPREADBIT

GLMAPREADBIT is a term sometimes used in documentation or language bindings to refer to the OpenGL constant that indicates read access when mapping buffer or memory regions. The canonical name in the OpenGL API is GL_MAP_READ_BIT. It is defined as a bit flag that can be used in the access mask passed to functions such as glMapBufferRange and glMapNamedBufferRange.

As a member of the GL_MAP_* family of bits, GL_MAP_READ_BIT (GLMAPREADBIT in some bindings) specifies that the mapped region should be readable by the client. It is commonly combined with other flags to customize access; for example, GL_MAP_READ_BIT | GL_MAP_WRITE_BIT would request a mapped range that can be read and written. Other related flags in the same family include GL_MAP_WRITE_BIT, GL_MAP_INVALIDATE_RANGE_BIT, GL_MAP_INVALIDATE_BUFFER_BIT, and GL_MAP_UNSYNCHRONIZED_BIT, among others.

Usage context entails mapping a region of a buffer or memory object for host-side access. By using GL_MAP_READ_BIT, an application declares its intention to read data from the mapped pointer. If synchronization is required, additional bits may be used, and the programmer should consider proper synchronization to avoid data hazards between CPU and GPU operations.

GLMAPREADBIT is effectively an alias for GL_MAP_READ_BIT in many bindings, serving the same role in enabling read access during mapping calls. It is part of the broader API feature set introduced with buffer mapping extensions, and it remains a standard mechanism for controlled host access to GPU resources.