glEnable

glEnable is an OpenGL API function used to enable a capability in the current OpenGL context. It takes a single argument, cap, a GLenum that identifies the capability to enable. The enabled state is part of the context’s global state and persists until it is disabled with glDisable. Enabling a capability typically changes how subsequent rendering operations are processed or tested.

Common capabilities include depth testing (GL_DEPTH_TEST), blending (GL_BLEND), face culling (GL_CULL_FACE), scissor testing (GL_SCISSOR_TEST), stencil testing (GL_STENCIL_TEST), and multisampling (GL_MULTISAMPLE). In older or compatibility profiles, texturing for legacy targets like GL_TEXTURE_2D could be enabled, but in modern core profiles many texture targets are deprecated and glEnable(GL_TEXTURE_2D) is not used.

In modern OpenGL, glEnable controls state that affects a particular stage or test rather than the fixed-function pipeline. For example, GL_DEPTH_TEST enables depth buffering so fragments undergo depth comparisons against the depth buffer, while GL_BLEND enables the blending stage controlled by glBlendFunc and related state. GL_CULL_FACE causes back-facing or front-facing triangles to be discarded according to the current face culling settings. Some capabilities relate to shader-based features (for instance, GL_PROGRAM_POINT_SIZE permits the shader to set point sizes).

Usage notes include ensuring the capability is supported by the current context and that any required buffers (depth, stencil) are bound. The function provides a simple mechanism to toggle features on and off; glDisable is used to turn them off. Properly managing enabled capabilities helps control rendering behavior and performance.