#71 Missed volume when raytracing BOTs

Raytrace (49)

When shooting a ray along the surface of a BOT which has stair step type
features, the first step may or may not be processed correctly, depending
on alignment. The riser to the next step (i.e., vertical section) incorrectly
acts as an exit when in fact the ray is leaving the first surface encountered
and entering the riser section.

A fictitious exit appears when the first concave corner is struck.

An example test case illustrating this problem is available from brlcad.


  • Sean Morrison

    Sean Morrison - 2010-01-27
    • milestone: 386421 --> other bug / workaround
    • assigned_to: nobody --> indianlarry
    • status: open --> closed-fixed
  • Sean Morrison

    Sean Morrison - 2010-01-27

    A fix for this issue was just made to BRL-CAD today that addresses this bug. If we don't run into any issues through our testing, this should get included in the upcoming 7.16.6 release (independent testing appreciated).

    The issue (as has been discussed extensively since the reporting) was due to the ray grazing the edge of a surface and getting incorrect in/out segments (technically it was getting in+in+out+out and 'presumably' performing invalid shifts resulting in in+out and in+out, missing the desired inner section.

    This change will definitely need more testing to make sure other BoT mesh ray tracing is not affected, but the problem should now be fixed.


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