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Translation Limits

Jim Su

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Hello all,

I'm trying to create a cursor that is constraint inside a square. It's going to be used like a joystick pad as an animation tool.

The cursor will be constraint in -1>x<1 , -1>y<1, and z = 0.

In SoftImage, this was easy, just apply constraint limits.

In Houdini, if I lock the Z parameter, then the cursor can no longer be moved freely (only one axis at a time) by the mouse.

If I use the clamp expression, the value locks at 0.

I created a workaround solution: a secondary cursor uses the clamp expression referencing the primary cursor that the mouse moves.

Does anybody have any ideas for a direct solution?



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Hmm ... maybe something like this?

tx: clamp(cubic(),-1,1)

ty: clamp(cubic(),-1,1)

tz: clamp(cubic(),0,0)

You can still move the handle beyond the bounds but the underlying object should stay within the constraints. You can keyframe these channels and the cubic() will do the regular interpolation.

BTW, nice to see you around. :)

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Thanks Ed!!! It worked!

The problem with my expression was:

Cross_tx : clamp(ch("../Control_tx),-1,1)

Control_tx : cubic()

So I used your expression for the top parameter:

Cross_tx: ch("../Control_tx)

Control_tx: clamp(cubic(),0,0)

This is also good because the animator can now blow away the clamp or adjust it if they want to.



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