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6.5. Reflection in a Plane 129
zero length. In practice, a triangle where this happens can be ignored
because if one of its sides has zero length, it has zero area and will
therefor e not be visible in a rendered image.
• Return hit code as follows:
if
< −0.001 or > 1.001 or < −0.001 or > 1.001 miss polygon
if (
+ ) > 1.001 miss polygon beyond edge P
1
→ P
2
if ≥ 0.0005 and ≤ 0.9995
and
≥ 0.0005 and ≤ 0.9995
and
≤ 0.9995 inside polygon
else if
< 0.0005 { along edge P
0
→ P
1
if < 0.0005 at vertex P
0
else if > 0.9995 at vertex P
1
else on edge P
0
→ P
1
not near vertex
}
else if
< 0.0005 { along edge P
0
→ P
2
if < 0.0005 at vertex P
0
else if > 0.9995 at vertex P
2
else on ...