Clipping algorithms are used in computer graphics to determine which parts of geometric primitives (such as lines, polygons, or curves) are visible within a specified viewing region, or viewport, and which parts are outside of the viewport and therefore should be discarded or "clipped."

Clipping algorithms serve several purposes :

Viewport clipping : Clipping algorithms are used to ensure that only the portions of a scene that are within the boundaries of the viewport are rendered on the screen. This prevents objects or parts of objects from being displayed outside of the visible area, which would waste computational resources and potentially obscure other elements of the scene.

Improving rendering performance : By clipping objects or portions of objects that are outside of the viewport, clipping algorithms can help improve rendering performance by reducing the number of primitives that need to be processed and rasterized. This is particularly important for real-time rendering applications, such as video games, where performance is critical.

Preventing rendering artifacts : Clipping algorithms help prevent rendering artifacts, such as overdraw and z-fighting, by ensuring that only the visible portions of objects are rendered. Overdraw occurs when multiple objects are rendered on top of each other, wasting computational resources. Z-fighting occurs when two or more surfaces occupy the same 3D space and compete for the same pixel on the screen, leading to flickering or incorrect rendering.

Culling invisible geometry : Clipping algorithms can also be used to cull, or discard, geometry that is entirely outside of the viewing frustum, or the portion of space that is visible to the camera. This helps further improve rendering performance by avoiding unnecessary processing of geometry that will not contribute to the final image.