Uploaded image for project: 'Minecraft: Java Edition'
  1. Minecraft: Java Edition
  2. MC-868

Detector Rail switches junction before Minecart passes detector (happens only with minecarts of certain speed)


    • Icon: Bug Bug
    • Resolution: Unresolved
    • None
    • Minecraft 1.4.2, Minecraft 1.4.5, Minecraft 1.4.6, Minecraft 1.4.7, Snapshot 13w05b, Snapshot 13w09a, Snapshot 13w09b, Minecraft 1.5, Snapshot 13w11a, Minecraft 1.5.1, Minecraft 1.5.2, Snapshot 13w18c, Snapshot 13w19a, Minecraft 1.6.2, Minecraft 1.6.4, Minecraft 13w38b, Minecraft 13w38c, Minecraft 13w39a, Minecraft 1.7.1, Minecraft 1.7.2, Minecraft 13w47e, Minecraft 13w48a, Minecraft 13w48b, Minecraft 1.7.3, Minecraft 1.7.4, Minecraft 14w02c, Minecraft 14w03b, Minecraft 14w04a, Minecraft 14w04b, Minecraft 14w05b, Minecraft 14w06a, Minecraft 14w06b, Minecraft 1.7.5, Minecraft 14w11b, Minecraft 1.7.9, Minecraft 14w17a, Minecraft 14w18a, Minecraft 14w20a, Minecraft 14w20b, Minecraft 14w21b, Minecraft 1.7.10, Minecraft 14w27b, Minecraft 14w30b, Minecraft 14w30c, Minecraft 14w32a, Minecraft 14w32b, Minecraft 14w32c, Minecraft 14w32d, Minecraft 14w33a, Minecraft 1.8, Minecraft 1.8.1-pre2, Minecraft 1.8.1-pre3, Minecraft 1.8.1, Minecraft 1.8.3, Minecraft 1.8.4, Minecraft 1.8.5, Minecraft 1.8.7, Minecraft 1.8.8, Minecraft 15w35e, Minecraft 15w44b, Minecraft 1.8.9, Minecraft 15w51b, Minecraft 16w02a, Minecraft 1.9 Pre-Release 1, Minecraft 1.9, Minecraft 1.9.1 Pre-Release 3, Minecraft 1.9.2, Minecraft 1.9.3 Pre-Release 3, Minecraft 1.9.4, Minecraft 16w20a, Minecraft 16w21a, Minecraft 16w21b, Minecraft 1.10 Pre-Release 1, Minecraft 1.10 Pre-Release 2, Minecraft 1.10, Minecraft 1.10.1, Minecraft 1.10.2, Minecraft 16w32a, Minecraft 16w32b, Minecraft 16w33a, Minecraft 16w35a, Minecraft 16w40a, Minecraft 16w41a, Minecraft 16w44a, Minecraft 1.11 Pre-Release 1, Minecraft 1.11.2, Minecraft 17w06a, Minecraft 1.12.1, Minecraft 18w50a, Minecraft 1.14 Pre-Release 1, Minecraft 1.14 Pre-Release 5, Minecraft 1.14.1, Minecraft 1.14.2 Pre-Release 1, Minecraft 1.14.2 Pre-Release 2, Minecraft 1.14.2 Pre-Release 3, Minecraft 1.14.2, Minecraft 1.14.3 Pre-Release 2, Minecraft 1.14.3 Pre-Release 3, Minecraft 1.14.4 Pre-Release 3, 1.14.4, 19w35a, 1.15.2, 20w07a, 20w14a, 1.16 Pre-release 2, 1.16 Pre-release 5, 1.16 Release Candidate 1, 1.16, 1.16.1, 20w28a, 20w29a, 20w30a, 1.16.2 Pre-release 1, 1.16.2 Pre-release 2, 1.16.2 Pre-release 3, 1.16.2 Release Candidate 1, 1.16.2 Release Candidate 2, 1.16.2, 1.16.3 Release Candidate 1, 1.16.3, 1.16.4 Pre-release 1, 1.16.4 Pre-release 2, 1.16.4 Release Candidate 1, 1.16.4, 20w45a, 20w46a, 20w48a, 20w49a, 20w51a, 21w03a, 1.16.5, 21w05a, 21w05b, 21w06a, 21w07a, 21w08b, 21w10a, 21w11a, 21w13a, 21w14a, 21w20a, 1.17, 1.17.1, 21w39a, 21w42a, 1.18 Pre-release 5, 1.18, 1.18.1, 22w03a, 22w06a, 22w14a, 22w18a, 1.19.1 Pre-release 5, 1.19.2, 1.19.3, 23w03a, 23w04a, 23w05a, 23w06a, 1.19.4, 1.20.1, 1.20.2 Pre-release 2, 23w51b
    • Confirmed
    • Minecart
    • Normal
    • Platform

      If you have a detector rail it can affect rails directly connected to it. A powered rail for example is powered and a curved rail can change orientation. Imagine now to have a t-junction setup like in

      The detector rail is on the left and passing it will cause the curved rail to change orientation. We start our cart not from the detector, but from where the rail is bend to. After starting the cart it goes into the bend and before leaving it, the detector will react. This causes a flicker in which the cart and the rail change orientation several times to then finally settle in the right-side position as in
      This basically means the detector rail caused a change of orientation for the bend rail before the minecart was even standing on it.

      I assume that the signaling goes by this: If the cart, would in a next step touch the detector rail, it fires. Since the rail is then bending in another direction there is an update as the minecart will now not go over the rail, causing another oriantation change. This then causes the detector to fire again going back to the situation in the beginning. The reason why this does not cause an endless loop is that each action takes one tick. Depending on the speed of the cart you will see a longer or shorter flicker then.

      What I expected was that the cart will go to the left, not the right as it actually did.

      Code analysis by pr0cess can be found in this comment.


      • Fixed in 16w02a? Using the setup described in start.png, the minecart sometimes "bounces" off the rail and goes backwards.
      • Half-fixed for 1.9.1-pre3.
        • Slow-moving minecarts will go the correct way, while fast moving minecarts will bounce back?!


      • Confirmed for 1.9-pre1. It seems to be affected by the speed of the minecart as well. Fast and slow minecarts don't trigger it, but minecarts with a medium-ish speed do.

        1. 1.gif
          652 kB
        2. 2.gif
          1.09 MB
        3. 2014-05-22_16.27.18.png
          1.25 MB
        4. 2014-05-22_17.27.55.png
          952 kB
        5. Alternative Cycle.png
          Alternative Cycle.png
          113 kB
        6. Alternative Setup.png
          Alternative Setup.png
          376 kB
        7. end.png
          152 kB
        8. javaw 2015-07-22 15-19-39-14.jpg
          javaw 2015-07-22 15-19-39-14.jpg
          494 kB
        9. MC-868-world.7z
          16 kB
        10. start.png
          83 kB

            Unassigned Unassigned
            markderickson [Mod] markderickson
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