glDisable

glDisable is an OpenGL API function used to disable a server-side capability in the currently active OpenGL context. It is the counterpart to glEnable and operates on the OpenGL state machine to turn off features that may affect rendering.

Prototype and parameter:

void glDisable(GLenum cap);

cap identifies the capability to disable, specified by a symbolic constant such as GL_DEPTH_TEST, GL_BLEND, GL_CULL_FACE, GL_SCISSOR_TEST, GL_STENCIL_TEST, or GL_TEXTURE_2D (legacy). The exact set of valid capabilities is defined by the OpenGL specification and the context profile.

Behavior and effects:

Calling glDisable disables the specified capability. If the capability was enabled, it becomes disabled; if it was already disabled, there is no change. The effect applies to subsequent rendering commands until the capability is re-enabled with glEnable or the context is reset. The current state can be queried with glIsEnabled, which returns whether a given capability is active.

Compatibility and usage:

In practice, glDisable is commonly used to control features such as depth testing (GL_DEPTH_TEST), blending (GL_BLEND), face culling (GL_CULL_FACE), and stencil or scissor tests. In modern OpenGL core profiles, the practical impact of glDisable may be reduced for certain fixed-function-like states, as shader-based rendering and explicit state management replace some fixed-function features. Nevertheless, glDisable remains a valid and widely used mechanism for managing state in compatibility contexts and in code that targets a broad range of OpenGL versions.

Errors:

If cap is not a valid capability, GL_INVALID_ENUM is generated. If no current context exists, GL_INVALID_OPERATION is generated.