Rename mediasource to source

[voretournament/voretournament.git] / misc / mediasource / netradiant-src / regression_tests / q3map2 / disappearing_sliver2 / README.txt

diff --git a/misc/mediasource/netradiant-src/regression_tests/q3map2/disappearing_sliver2/README.txt b/misc/mediasource/netradiant-src/regression_tests/q3map2/disappearing_sliver2/README.txt
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-DESCRIPTION OF PROBLEM:
-=======================
-
-The example map, maps/disappearing_sliver2.map, contains an example of this
-bug.  The triangle sliver surface in the middle of the room is not rendered
-in the final BSP.
-
-To trigger the bug, compile the map; you don't need -vis or -light.  Only
--bsp (the first q3map2 stage) is necessary to trigger the bug.  The only
-entities in the map are a light and a info_player_deathmatch, so the map will
-compile for any Q3 mod.
-
-
-SOLUTION TO PROBLEM:
-====================
-
-It was discovered that BaseWindingForPlane() in polylib.c did some sloppy
-mathematics with significant loss of precision.  Those problems have been
-addressed in commits to revisions 371 and 377.
-
-
-POSSIBLE SIDE EFFECTS:
-======================
-
-Great care was taken to preserve the exact behavior of the original
-BaseWindingForPlane() function except for the loss of precision.  Therefore
-no negative side effects should be seen.  In fact performance may be
-increased.
-
-
-IN-DEPTH DISCUSSION:
-====================
-
-Turns out that the problem is very similar to the original disappearing_sliver
-regression test.  You should read that README.txt to familiarize yourself
-with the situation.
-
-The thing we need to look at is side 0 of brush 0, if you applied
-winding_logging.patch from disappearing_sliver regression test:
-
-  In ParseRawBrush() for brush 0
-      Side 0:
-          (6784.000000 16241.000000 -1722.000000)
-          (6144.000000 16083.000000 -1443.000000)
-          (6144.000000 16122.000000 -1424.000000)
-
-That is the exact plane defninition of our problem sliver, and in fact those
-are also the correct points for the actual vertices of the triangle.
-
-Now the results of the winding for this surface after all the clipping takes
-place:
-
-  (6784.12500000 16241.02343750 -1722.06250000)
-  (6144.00000000 16082.99218750 -1443.00781250)
-  (6144.00000000 16122.00000000 -1424.00390625)
-
-As you can see, 6784.12500000 is more than epsilon distance (0.1) away from
-the correct point.  This is a big problem.
-
-After we apply the fix committed in revision 371, the result after clipping
-is this:
-
-  (6784.06250000 16241.01171875 -1722.03515625)
-  (6144.00000000 16082.99609375 -1443.00781250)
-  (6144.00000000 16122.00000000 -1424.00585938)
-
-As you can see, all points but one have an increase in accuracy.  This is
-still not accurate enough in my opinion, but is a step in the right direction.
-
-After the fix committed in revision 377, which is a further attempt to address
-BaseWindingForPlane(), we get the following accuracy:
-
-  (6784.00000000 16241.00000000 -1722.00000000)
-  (6144.00000000 16083.00000000 -1443.00000000)
-  (6144.00000000 16122.00000000 -1424.00000000)
-
-It's just a fluke for this particular case, but obviouly revision 377 looks
-favorably upon this regression test, because there is zero percent error.
-
-
-MORE NOTES:
-===========
-
-I attempted to improve upon revision 371 by streamlining the code in
-BaseWindingForPlane() some more.  Those attempts were committed as revision
-375.  After revision 375:
-
-  (6784.09375000 16241.01757812 -1722.04687500)
-  (6144.00000000 16082.99414062 -1443.00390625)
-  (6144.00000000 16122.00000000 -1424.00097656)
-
-Revision 375 has since been reverted (undone) because of the loss in
-accuracy.  Revision 377 is a fix for those failed attempts.