In the fields related to geometric modelling, it is fundamental to count on robust. In this work we present a new algorithm for testing the intersection between a segment and a polygon in 3D space. This algorithm is robust and efficient, and it is the basis of most operations developed in geometric modelling. After, we will apply this algorithm to a classic problem in computer graphics: determining the hidden faces of a scene using the ray-casting algorithm. To solve the problem, an object-oriented approach will be used.