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Thread: Simple vector math is not simple

  1. #1
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    Simple vector math is not simple

    Here is a simple node setup:
    Click image for larger version. 

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    I think the math behind the setup supposed to be A-B+B=A, but the result don't return A to me.
    What I did wrong?

  2. #2
    Aren't vectors normalized after each operation? I could be very wrong here. Been a while.
    What I mean is

    a = 1,1,1
    b = 1,0,0
    a + b = 1, 0.5, 0.5
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  3. #3
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    Quote Originally Posted by Bytehawk View Post
    Aren't vectors normalized after each operation? I could be very wrong here. Been a while.
    What I mean is

    a = 1,1,1
    b = 1,0,0
    a + b = 1, 0.5, 0.5
    Absolutely they are not.
    Your's 1,0.5,0.5 is not normalized.
    Normalized means sqrt(x^2 + y^2+z^2)=1
    sqrt(1^2+0.5^2+0.5^2) = 1.224745

    Mewnow, try Const > Vector instead to see what it'll give you, instead of MDD Cache..
    MDD Cache node is not part of LW 2019. I don't have it.
    So, contact author.
    Last edited by Sensei; 05-23-2019 at 05:42 AM.

  4. #4
    thanks for correcting me. I haven't done a lot of 3d stuff lately.
    www.bytehawk.net

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  5. #5
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    Maybe I didn't made it clearly, sorry.
    I want to find out the differences of 2 mdd caches, do some stuff, and add it back to the original one.
    Yes, I know I did the wrong thing about this. But how to make it right?

    @Sensei:
    Yes, I try to math vector nodes, A(1 1 1) and B(1 0 0), so A-B = 0 1 1, next A-B+B=1 1 1.
    And, I use DP Mdd Cache node, there is also MDD Displacement node in my LW11.6.3

    EDIT: Maybe I should attach a simple scene file, sorry.
    Here is my little scene file. math.zip
    Last edited by mewnow; 05-23-2019 at 07:15 AM. Reason: attach scene file

  6. #6
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    Quote Originally Posted by mewnow View Post
    @Sensei:
    Yes, I try to math vector nodes, A(1 1 1) and B(1 0 0), so A-B = 0 1 1, next A-B+B=1 1 1.
    And, I use DP Mdd Cache node, there is also MDD Displacement node in my LW11.6.3
    If it works with constant vectors, but not works with MDD cache, then problem is the most likely inside of MDD Cache...

    Did you try downloading the latest versions of DP Kit to check it? Maybe it has been fixed already.

  7. #7
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    Sensei: The native MDD Displacement node give me the same result, I have upload a simple scene file, maybe you have a look at it. Thanks.

  8. #8
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    What effect should I see?

    There is pulsing ball no matter if I plug MDD Displacement directly or through sub+add network with uvball_stage1.mdd.
    uvball_stage2.mdd it slightly moves in one direction.

    Show me some screen-shot..

    I tried ATM LW 2018.0.7.

    ps. I see one MDD Displacement uses uvball_stage1.mdd and other one uvball_stage2.mdd.
    Shouldn't we focus on A-B+B=A the first? And then go forward with 2 mdds files..
    Last edited by Sensei; 05-23-2019 at 07:44 AM.

  9. #9
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    Sorry, not clearly everytime.
    I want to find out the differences between stage1 and stage2(make some stuff with the differences), then add the differences back to stage1, so the finally result should be stage2.

    I find out the differences by stage2.mdd - stage1.mdd, this works fine. But I use a "Add" node to add it back to stage1, don't get the stage2.

    Edit: What screen-shot? Displacement node setup?
    Click image for larger version. 

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    Last edited by mewnow; 05-23-2019 at 07:57 AM.

  10. #10
    Goes bump in the night RebelHill's Avatar
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    Change your MDD nodes to match by coords, not by nodes.
    LSR Surface and Rendering Tuts.
    RHiggit Rigging and Animation Tools
    RHA Animation Tutorials
    RHR Rigging Tutorials
    RHN Nodal Tutorials
    YT Vids Tuts for all

  11. #11
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    @RebelHill:
    Yeah, it works.
    I would like to use DP MDD Cache, but it don't have a match by coordinates option, if this can be solved?

  12. #12
    Goes bump in the night RebelHill's Avatar
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    Dont think so... you tried turning on the world coord option. Doubt it makes a difference, but you never know.
    LSR Surface and Rendering Tuts.
    RHiggit Rigging and Animation Tools
    RHA Animation Tutorials
    RHR Rigging Tutorials
    RHN Nodal Tutorials
    YT Vids Tuts for all

  13. #13
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    I think I found a workaround,
    the issue is caused by the second evaluation of the same MDD Cache node,
    one for Adding and then for Subsracting,
    in this case the node editor seems to miss/decal point iteration (?),
    so if you use a different MDD Cache for Adding and Substracting
    using a copy of the node, this should work,
    note that it shouldn't use more memory,
    because it uses instance of the MDD file.

    Denis.

    'updated)
    ...To be clear, I noted this issue only in LW2015 and previous versions,
    where this tip may help,
    but no such issue in LW2018-2019,
    because there's no more iteration, we can now
    match the exact evaluated point.
    Last edited by dpont; 05-24-2019 at 03:08 AM.

  14. #14
    Angry Mac User Otterman's Avatar
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    ....and this is why I hate nodes and yet to embrace LW2019. Not one single Newtek tutorial to explain this sh*t!

  15. #15
    Goes bump in the night RebelHill's Avatar
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    Not sure why you think NT would have stuff explaining third party tools... but aside from that specific case, there's TONS of material covering nodes spread about, if not from NT, then from others.
    LSR Surface and Rendering Tuts.
    RHiggit Rigging and Animation Tools
    RHA Animation Tutorials
    RHR Rigging Tutorials
    RHN Nodal Tutorials
    YT Vids Tuts for all

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