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Thread: Expressions constantly failing

  1. #1
    eye kan kode gud jrandom's Avatar
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    Expressions constantly failing

    I create a Master Channel, set a keyframe value for it, then link up an object or camera's position to it. Moving the MC keyframe value alters the linked channel as expected.

    Now, if I select anything else or close/reopen the graph editor and alter the MC's value, the other items that use the MC channel in their expressions fail to change, even though they have the little dot indicating they're hooked up to the expression, and double-clicking on the expression itself brings up those very same channels.

    Does anyone know why this basic expression functionality would fail like this?

  2. #2
    Code Muppet evenflcw's Avatar
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    Could we have a look at the expressions that are supposedly faulty or the scene (or part of) even!?

    Personally I prefer entering expressions via Motion Options. It's more flexible (Before/After IK flag and if your using Motion Mixer you can arrange the evaluation order). That will obviously only work for motion channels though... .

  3. #3
    eye kan kode gud jrandom's Avatar
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    I've attached a screenshot showing the three camera channels that show up when I double-click the "Camera Zoom Factor" expression (showing they are linked to it), along with the master channel used in the expression itself. The master channel currently has a value of 3.2, but altering this value does not alter the zoom factor for the cameras.

    (I'm attempting to set up a stereographic rig and need to be able to tie things together via expressions. I'm having this same problem with my interocular distance expression.)
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  4. #4
    Code Muppet evenflcw's Avatar
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    Spaces. You shouldn't have unnecessary spaces in names in equations and expression/code syntax. Which is why you should avoid them anywhere in a 3d program where you might need to reference by name at times.

    It seems you have to recreate the MasterChannel from scratch meerly renaming didnt work form me. So just recreate, and don't use spaces.

  5. #5
    eye kan kode gud jrandom's Avatar
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    No spaces, got it!

    (You'd think I'd know these things, being a professional programmer and all... .NET must have rotted my brain )

  6. #6
    eye kan kode gud jrandom's Avatar
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    So I tried again (starting from scratch) without spaces and it still didn't work. Altering the value in one channel has no effect on another channel using an expression containing the first channel.

    (See [Camera_Preview.ZoomFactor] for an example. I've grouped the channels I'm using under the name Camera_Control -- altering the value of MC.CC_Field_of_View should effect the camera's zoom factor but it doesn't.)
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    Last edited by jrandom; 02-27-2010 at 11:03 PM.

  7. #7
    Goes bump in the night RebelHill's Avatar
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    Theres no issue with the expressions on that scene posted. If you put both the MCUtilzoomfactor, and MCccfieldofview channels u have into the graphs channel list, select to view just the mMCccFOV channel, select the keyframe at 0 in the graph, shift+select the MCutilZF channel, push "a" to fit the view in the graph, click in the open graph space, and as u drag up n down, ull see the dotted graph line for the UtilZF, moving... showing that the expression works, and is applied correctly.

    So whilst ur affecting a channel uve setup to take the zoomfactor input, and it works, its not actually connected to the cameras zoom factor channel envelope, camera_preview.zoomfactor.

    Either hook the mcUtilZF to it, or hook the expression driving the utilZF directly to it.
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  8. #8
    eye kan kode gud jrandom's Avatar
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    Quote Originally Posted by RebelHill View Post
    Theres no issue with the expressions on that scene posted. If you put both the MCUtilzoomfactor, and MCccfieldofview channels u have into the graphs channel list, select to view just the mMCccFOV channel, select the keyframe at 0 in the graph, shift+select the MCutilZF channel, push "a" to fit the view in the graph, click in the open graph space, and as u drag up n down, ull see the dotted graph line for the UtilZF, moving... showing that the expression works, and is applied correctly.
    Now this is bizarre because when I do what you describe above, it still does not work -- the dotted graph line stays where it is. Why would this behave differently on your machine? What could have gone wrong with mine?

    So whilst ur affecting a channel uve setup to take the zoomfactor input, and it works, its not actually connected to the cameras zoom factor channel envelope, camera_preview.zoomfactor.
    Camera_Preview.ZoomFactor is linked to the expression e_Zoom_Factor (which links up to the rest which you verified as working correctly on your machine).

    It's good to know I structured it right. Now the question is, why does it not work on my particular system?

    I'm running Lightwave 9.6 on Mac OS X 10.6.2.

  9. #9
    eye kan kode gud jrandom's Avatar
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    AH! This is interesting: turns out that yes, it is working, but none of my windows are being updated in realtime. I have to select another object and suddenly it kicks in.

    Expressions used to update my viewports and graph editor window instantly. Did I accidentally shut something off?

  10. #10
    TD/Animator lino.grandi's Avatar
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    Didn't see your scene...but I wonder if you have Auto Key turned off.

    If is off, you don't get RT update of expressions effects.

  11. #11
    eye kan kode gud jrandom's Avatar
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    Quote Originally Posted by lino.grandi View Post
    Didn't see your scene...but I wonder if you have Auto Key turned off.

    If is off, you don't get RT update of expressions effects.
    Autokey is on. If I go to the graph editor options and check "lazy update" then after I move the value (releasing the mouse button) and then move the mouse again the viewports will suddenly update. Leaving lazy updating off requires me to select a different object in layout before the display will update.

    It appears that if I have an expression tied to, say, the position of an object and I move that object, then I get realtime updates in the viewports but this doesn't seem to happen if I'm dragging the value of a key for a master channel up/down.

    Would this be considered a bug in Lightwave 9.6 for Mac?

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