glClearStencil

glClearStencil is a function in OpenGL used to set the stencil buffer to a specific value. The stencil buffer is a part of the framebuffer that can be used for masking and other per-pixel operations, often employed in advanced rendering techniques.

When glClearStencil is called, it specifies the integer value that will be used to clear the stencil buffer. The stencil buffer is a grid of memory that stores integer values for each pixel. These values can be manipulated by stencil test operations during rendering.

The typical use case for glClearStencil is to prepare the stencil buffer before drawing or performing stencil operations. For instance, to clear the stencil buffer to all zeros, you would call glClearStencil(0). The clear operation itself is then performed by the glClear function, specifying GL_STENCIL_BUFFER_BIT as one of the buffers to clear.

The value used with glClearStencil can range from 0 to 2^N - 1, where N is the number of bits allocated for the stencil buffer in the framebuffer. This allows for a range of values to be used for masking and testing. Using glClearStencil is a prerequisite for using glClear with the stencil buffer bit.