Problem 1776

Created attachment 353 [details]
Left: OpenGL image (no problem), Center: RayTracer (with problem), Right RayTracer (no problem)

When creating a G4ExtrudedSolid with a particular set of points, the created shape appears fine in regular visualization (such as OpenGL), but is wrong in tracking (it has an unphysical extension in one area, shown in the attached RayTracer image).

We see this with the simplest form of G4ExtrudedSolid, just a simple polygon that is extruded in Z with no variation of scale and no x and y offset,
so just a straight extrusion in Z.

If one modifies this set of points by simply cutting off the first point from the list and instead appending this as the last point (which should make the same solid), the bug vanishes. That is, it visualizes fine in RayTracer.

I attach the OpenGL image and the two RayTracer images, one with the bug, the other without (caused by moving the first point of the list to the last point).

The list of points follows:
186 points. Unit in our test was mm.

6.8 -17.9
6.0 -18.3
5.6 -18.5
4.8 -18.8
4.3 -18.9
3.4 -19.0
1.9 -19.1
1.2 -19.0
-3.5 -18.3
-4.1 -18.2
-4.8 -18.0
-5.6 -17.6
-6.9 -16.9
-7.5 -16.5
-9.1 -15.3
-10.3 -14.1
-10.9 -13.5
-11.5 -12.8
-11.7 -12.3
-12.1 -11.6
-12.4 -11.0
-12.6 -10.2
-12.8 -9.6
-12.9 -9.0
-13.0 -8.1
-13.1 -6.8
-13.2 -6.0
-13.6 -5.2
-14.3 -4.7
-15.8 -4.6
-16.4 -4.5
-17.2 -4.3
-18.0 -4.0
-18.8 -3.6
-19.3 -3.3
-20.0 -2.8
-20.3 -2.6
-21.0 -2.0
-21.2 -1.6
-21.7 -1.1
-22.1 -0.4
-22.6 0.4
-23.0 1.2
-23.3 1.9
-23.7 3.1
-23.9 3.9
-24.1 4.7
-24.1 6.1
-23.9 7.2
-23.7 8.0
-23.0 10.2
-22.6 11.2
-22.6 11.3
-22.1 12.0
-21.7 12.7
-21.2 13.4
-20.8 13.9
-20.2 14.4
-19.6 15.0
-18.8 15.5
-16.8 16.8
-16.0 17.2
-13.8 18.1
-12.3 18.5
-11.8 18.6
-11.0 18.6
-10.3 18.6
-9.8 18.5
-8.7 18.2
-6.3 17.2
-5.5 16.9
-0.3 16.1
0.5 15.9
1.3 15.6
4.3 14.3
6.6 13.1
9.4 11.3
11.4 9.7
15.3 6.3
17.2 4.8
20.4 2.7
21.7 1.3
22.3 0.4
22.8 -1.0
22.9 -1.4
22.8 -3.8
22.6 -4.5
22.3 -5.3
22.2 -5.4
21.6 -6.3
21.4 -6.6
20.7 -7.3
14.7 -12.2