GLuints

GLuints are unsigned integer handles used by OpenGL to identify graphics objects. In OpenGL headers, GLuint is defined as an unsigned 32-bit type and serves as an opaque reference to resources such as textures, buffer objects, shader and program objects, vertex array objects, framebuffer objects, and renderbuffers. A GLuint does not reveal the object’s internals; software uses the handle to refer to the resource in subsequent API calls.

Handles are created by specific GL calls. For most objects, the application requests new names with glGen functions (for example glGenBuffers, glGenTextures) or, for shaders and programs, by glCreateShader and glCreateProgram. The driver writes one or more GLuints that identify the resources. After creation, the handles are used in binding, modifying, or querying the object (for example glBindBuffer, glTexImage2D, glAttachShader).

Lifecycle and deletion follow a simple rule: resources are deleted with glDelete calls (glDeleteBuffers, glDeleteTextures, etc.). Deletion may not immediately free the numeric identifier, as the implementation may reuse the handle later. Objects must be valid in the current context when used; operations on deleted objects produce errors.

Special value 0 is reserved and denotes “no object.” Binding a target to 0 unbinds the target (for example glBindBuffer(target, 0)) and 0 is not a valid resource handle.

Context and portability considerations: GLuints are per-context identifiers. Resources created in one GL context are not valid in another unless contexts share data. GLuint is typically a 32-bit unsigned integer, but applications should rely on the GL API types (GLuint, GLuint64) and perform error checking after API calls.