And it has been added to previous and the output if

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: what we expect from the Note: clipping operation against each edge clipping Sutherland-Hodgeman Clipping Sutherland-Hodgman basic routine: • Go around polygon one vertex at a time • Current vertex has position p Current • Previous vertex had position s, and it has been added to Previous and the output if appropriate the Sutherland-Hodgeman Clipping Edge from s to p takes one of four cases: Edge takes (Orange line can be a line or a plane) inside outside inside outside inside s p p output s i output p outside p inside p s no output i output p output outside s Sutherland-Hodgeman Clipping Four cases: • s inside plane and p inside plane – Add p to output Add – Note: s has already been added Note: • s inside plane and p outside plane – Find intersection point i Find – Add i to output Add • s outside plane and p outside plane outside – Add nothing • s outside plane and p inside plane – Find intersection point i Find – Add i to output, followed by p Add Point-to-Plane test A very general test to determine if a point p is “inside” very a plane P, defined by q and n: defined (p - q) • n < 0: p inside P (p - q) • n = 0: p on P (p - q) • n > 0: p outside P Remember: p • n = |p| |n| cos (θ) Remember: |p| θ = angle between p and n angle q q n p P q n p P p P n Finding Line-Plane Intersections Edge intersects plane P where E(t) is on P Edge (t) • q is a point on P • n is normal to P (L(t) - q) • n = 0 t = [(q - L0) • n] / [(L1 - L0) • n] • The intersection point i = L(t) for this value of t The Line-Plane Intersections Again, lots of opportunity for optimization Again,...
View Full Document

This document was uploaded on 01/29/2014.

Ask a homework question - tutors are online