Source Code for Module MeatEngine.RayTrace.triangle

 1  import MeatEngine.Math.vector 
 2  import intersect 
 3   
 4  EPSILON=0.000001 
 5   
 6  """ 
 7  from "Fast, Minimum Storage Ray/Triangle Intersection" by Moller and 
 8  Trumbore 
 9  """ 
10   
11   
12 -def intersectRayTriangle(orig, dir, 
13                           v0, v1, v2, 
14                           cullBackface=False): 
15      """ 
16      intersectTriangle takes 5 points (origin, direction, and three 
17      vertices) and returns a distance and a u,v 
18      """ 
19   
20      edge1=v1.sub(v0) 
21      edge2=v2.sub(v0) 
22   
23      pVec = dir.cross(edge2) 
24      det = edge1.dot(pVec) 
25   
26      if cullBackface: 
27          if det<EPSILON: 
28              # backfacing, return None 
29              return None 
30   
31          tVec=orig.sub(v0) 
32          u=tVec.dot(pVec) 
33          if (u < 0 or u > det): 
34              return None 
35   
36          qVec=tVec.cross(edge1) 
37   
38          v=dir.dot(qVec) 
39          if (v < 0 or v > det): 
40              return None 
41   
42          t=edge2.dot(qVec) 
43          invDet=1.0/det 
44   
45          t *= invDet 
46          u *= invDet 
47          v *= invDet 
48      else: 
49          #not culling 
50   
51          if (det > -EPSILON and det < EPSILON): 
52              # edge-on 
53              return None 
54   
55          invDet= 1.0/det 
56          tVec=orig.sub(v0) 
57   
58          u=tVec.dot(pVec)*invDet 
59          if (u<0.0 or u>1.0): 
60              return None 
61   
62          qVec=tVec.cross(edge1) 
63   
64          v=dir.dot(qVec)*invDet 
65   
66          if (v<0.0 or v>1.0): 
67              return None 
68   
69          t=edge2.dot(qVec)*invDet 
70   
71      if u+v>1: 
72          return None 
73   
74      pos=v0.add(edge1.mul(u).add(edge2.mul(v))) 
75       
76      return intersect.Intersection(t, 
77                                    pos, 
78                                    (u,v), 
79                                    edge1.cross(edge2)) 
80