Finding X-section of any arbitrary polygonal model

Hi, I know the topic is very old. I would still like to knowabout that. I have an arbitrary polygonal model that consists of around onemillion polygons. If I pass a planethrough the model, what would be the most convenient way to find the X-section . As the model is very large, I don’t want tocount all the polygons.
Thanks in advance.

Use space-partitioning. Insert your model into a BSP tree, and only process the nodes that intersect
with the plane.