Object Space - approaches for visible surface determination
The second approach as object-space that compares all objects directly along with each other inside the scene definition and removes those objects or portion of objects which are not visible. In terms of pseudo-code, we comprise:
for (each object in the world)
determine those parts of the object whose view is unobstructed (not blocked)
parts of it or any other object;
draw those parts in the appropriate color;
This approach compares all of the n objects to itself and to another objects, and discarding unseen portions. Hence, the computational effort is proportional to n2.