glEnableGLDEPTHTEST

glEnable is an OpenGL function used to turn on a capability for rendering. One common capability is GL_DEPTH_TEST, which enables depth testing. When GL_DEPTH_TEST is enabled, OpenGL compares the depth value of each fragment with the corresponding value in the depth buffer to decide whether the fragment should be drawn.

There is no function named glEnableGLDEPTHTEST. The correct call to enable depth testing is glEnable(GL_DEPTH_TEST). Disabling depth testing is done with glDisable(GL_DEPTH_TEST).

Depth testing requires a depth buffer attached to the current framebuffer. The depth buffer stores per-pixel depth values and is typically created when the window or context is created with a depth buffer (for example, a 24-bit depth buffer). Before rendering a frame, the depth buffer is usually cleared with glClear(GL_DEPTH_BUFFER_BIT). The depth comparison is controlled by glDepthFunc, with the default being GL_LESS, meaning a fragment passes if its depth value is less than the stored value. If a fragment passes, its depth value can be written to the depth buffer, unless depth writes are masked by glDepthMask.

Depth testing interacts with other state. For example, glDepthMask controls whether the depth buffer is writable, and glDepthRange can adjust the mapping of normalized device coordinates to depth values. Common issues include z-fighting from insufficient depth precision, which can be mitigated by adjusting the near/far plane or using a reversed depth buffer strategy.

In typical pipelines, depth testing is enabled after a depth buffer is created, and the depth buffer is cleared at the start of each frame to ensure correct visibility computations.