Example 2 - Line Not Passing Through Window

The next step we consider if tvalue is entering or exiting by using inner product.

(Q-P) = (2+8,14-2) = (10,12)

At top edge (Q-P)nT = (10,12)(0,10) = 120 > 0 exiting so we set tmax = 8/12

At left edge (Q-P)nL = (10,12)(-10,0) = -100 < 0 entering so we set tmin = 8/10

Because tmin > tmax then we don't draw a line.

From P. Asokarathinam -- see details 27.11.1996