Algorithm 3.

Capturing needle penetration of penrose drain

1:	procedure captureNeedlePenetration
2:	set toggle = 0 at start of simulation
3:	if toggle == 0 then
4:	for each surface triangle of penrose drain do
5:	find vector w0 = x0 − xa
6:	if |w0| > DT then
7:	continue to next triangle (broad phase elimination)
8:	end if
9:	find outward normal n̂ of the triangle
10:	find projected penetration point P = xa + (w0.n̂)n̂
11:	if P lies outside the triangle then
12:	continue to next triangle
13:	end if
14:	compute vectors w and w1
15:	if w.w1 < 0 then
16:	set toggle = 1
17:	identify triangle
18:	initiate penetration
19:	end if
20:	end for
21:	end if
22:	if toggle == 1 then
23:	compute vectors w w1 and w2 in identified triangle
21:	if w1.w2 ≤ 0 then
25:	set toggle = 0
26:	confirm penetration
27:	end if
28:	if w.w1 ≥ 0 and w1.w2 ≥ 0 then
29:	set toggle = 0
30:	no penetration
31:	end if
32:	end if
33:	end procedure