glClearDepth

glClearDepth is a function in the OpenGL API used to set the depth value used when the depth buffer is cleared. The depth buffer is a part of the framebuffer that stores depth information for each pixel, which is used for depth testing and occlusion queries. The glClearDepth function allows developers to specify the value that the depth buffer should be cleared to when the glClear function is called with the GL_DEPTH_BUFFER_BIT flag.

The function prototype for glClearDepth is as follows:

void glClearDepth(GLdouble depth);

The depth parameter is a double-precision floating-point value that specifies the depth value to which the depth buffer should be cleared. The value should be in the range [0.0, 1.0], where 0.0 represents the nearest depth and 1.0 represents the farthest depth.

By default, the depth buffer is cleared to 1.0, which means that all pixels are considered to be at the farthest depth. However, developers can use the glClearDepth function to set a different depth value if needed. For example, if a developer wants to clear the depth buffer to a value of 0.5, they can call glClearDepth(0.5) before calling glClear(GL_DEPTH_BUFFER_BIT).

It is important to note that the glClearDepth function only sets the depth value used for clearing the depth buffer. It does not actually clear the depth buffer. To clear the depth buffer, the developer must call the glClear function with the GL_DEPTH_BUFFER_BIT flag.

In summary, glClearDepth is a useful function in the OpenGL API that allows developers to specify the depth value used when the depth buffer is cleared. By setting an appropriate depth value, developers can control the behavior of depth testing and occlusion queries in their OpenGL applications.