2-D Clipping algorithmsLine clipping algorithms such as Cohen Sutherland line clipping algorithm - The Logic Tutorial

2D Clipping Algorithms: Cohen-Sutherland Line Clipping Algorithm

The Cohen-Sutherland Line Clipping Algorithm is used in computer graphics to efficiently clip lines against a rectangular viewing window. Let's explore the algorithm step by step:

1. Initialize the clipping window: Define the clipping window boundaries as a rectangle with four edges.
2. Assign codes to each endpoint: Each endpoint of the line is assigned a 4-bit code based on its position relative to the clipping window. The bits represent the position of the endpoint with respect to the top, bottom, right, and left edges of the window.
3. Check for trivial acceptance or rejection: If both endpoints have a code of 0000, the line lies entirely within the clipping window and can be accepted without further processing. If both endpoints have a non-zero bitwise AND result, the line lies entirely outside the clipping window and can be rejected.
4. Clip against each edge: For each edge of the clipping window, determine if the line intersects the edge. If it does, calculate the intersection point using parametric line equations.
5. Repeat the process: After clipping against each edge, update the codes of the endpoints and repeat steps 3 and 4 until the line is either completely inside the clipping window or completely outside.

Let's illustrate the algorithm with an example:

In this example, we have a line that intersects the clipping window. By applying the Cohen-Sutherland algorithm, we clip the line against each edge of the window until it fits entirely within the boundaries.

The Cohen-Sutherland Line Clipping Algorithm is efficient and straightforward, making it widely used in computer graphics for line clipping against rectangular viewing windows.