3d line between to nulls – REVISITED

[Todd Kopriva]

This thread has what I think that you’re looking for:
https://forums.creativecow.net/thread/2/986902

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Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
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[Tom Gomez]

That’s a super solution. But I’m hoping there’s a way to make something magic like that work in 3D…

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[Tom Gomez]

Here’s my solution…

Not elegant maybe, but works great. I’d love any feedback or enhancements.

This set of expressions will allow you to make a 3D line between any two 3d layers you stick it between. It will respond to depth of field, moving layers, etc. with no stacking issues and no need to use beam filter. The nice thing is that you can modify it so your line could have all kinds of effects or change shape, etc.

1) Stick a rectangular shape layer (with 3D checked and position dimensions separated) between any two 3D layers (that have position dimensions separated). The anchor of your shape layer should be (0,0,0).

2) Make the width of your rectangle exactly match the distance between those layers with this expression. (You need to apply this expression to JUST the width parameter of the rectangle.) I did it this way:

In a SLIDER:

point1=this_comp.layer(thisLayer, -1).position;
point2=this_comp.layer(thisLayer, 1).position;
length(point1, point2)

In my rectangle in the size parameter:

temp = effect(“Slider Control”)(“Slider”);
[temp[0], value[1]]

3) Put the shape exactly between the two layers in 3D space.

In X:
(thisComp.layer(thisLayer,-1).transform.xPosition+thisComp.layer(thisLayer, 1).transform.xPosition)/2

In Y:
(thisComp.layer(thisLayer,-1).transform.yPosition+thisComp.layer(thisLayer,1).transform.yPosition)/2

In Z:
(thisComp.layer(thisLayer,-1).transform.zPosition+thisComp.layer(thisLayer,1).transform.zPosition)/2

4) Orient the layer so it exactly connects the two other layers:

In ORIENTATION:

lookAt (thisComp.layer(thisLayer,-1).transform.position, thisComp.layer(thisLayer,1).transform.position)

Again, I’d love any suggestions. Thanks!

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[Tom Gomez]

PS. And change the line’s y rotation to 90.

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[Joao Peachtree]

Hi Tom!

I’m a newbie in expressions and I’m trying to do your 3D “rope”, but I get an error when i get to the XYZ positioning saying: “Class ‘Group’ has no property or method named ‘xPosition’”.
Any thoughts on how i could resolve this would be much appreciated!

Thanks a lot

[Tom Gomez]

Be sure to right click on your position transformation and tell it to “separate dimensions”… Then your x,y,z will turn into three separate values that the expression wants.

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[Joao Peachtree]

Thanks for the quick reply!
I did that before, sorry if I wasn’t clear. Do you have any other idea why it isn’t working?

The Slider and the Orientation expressions are working.
I’m running CS5

Thanks

[Tom Gomez]

I won’t be able to check into it for a few days… But I’d be happy to.

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[Tom Gomez]

Greetings Joao,

Sorry it took so long to get back to you. Hopefully this is still helpful. I’ve just revamped these expressions for a 3d line and maybe it will help.

First, create a shape rectangle layer, make it 3d, give it a fill, place it between any two 3d layers (so for example layer 1 is a 3d layer, layer would be this layer, and layer 3 would be another 3d layer).

Next, give it two expression sliders. Call the first one LINE LENGTH MODIFIER, the second LINE WIDTH. For now, give those the values 1 and 4 respectively.

Nexy, add these expressions:

To the rectangle’s size property:

x = (effect(“LINE LENGTH MODIFIER”)(“Slider”));
point1 = ((thisComp.layer(this_layer,-1).position)*x);
point2 = ((thisComp.layer(this_layer,1).position)*x);
y = (length(point1, point2))*(x);
w = effect(“LINE WIDTH”)(“Slider”);

[y, w]

To the position property of the layer:

a = thisComp.layer(this_layer,-1).transform.position[0];
b = thisComp.layer(this_layer,1).transform.position[0];
c = (a+b)/2;
d = thisComp.layer(this_layer,-1).transform.position[1];
e = thisComp.layer(this_layer,1).transform.position[1];
f = (a+b)/2;
g = thisComp.layer(this_layer,-1).transform.position[2];
h = thisComp.layer(this_layer,1).transform.position[2];
i = (a+b)/2;

[c, f, i]

On the layer’s orientation property:

lookAt (thisComp.layer(this_layer,-1).transform.position, thisComp.layer(this_layer,1).transform.position)

FINALLY, set the layer’s rotation to 90.

You can copy and paste the whole line layer between any two 3d layers and it will automatically adjust to the new layers.

Viola.

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[Garrett Eaton]

Great expression Tom; thanks! There’s just a couple typos in there that I fixed so people can just copy/paste:

a = thisComp.layer(this_layer,-1).transform.position[0];
b = thisComp.layer(this_layer,1).transform.position[0];
c = (a+b)/2;
d = thisComp.layer(this_layer,-1).transform.position[1];
e = thisComp.layer(this_layer,1).transform.position[1];
f = (d+e)/2;
g = thisComp.layer(this_layer,-1).transform.position[2];
h = thisComp.layer(this_layer,1).transform.position[2];
i = (g+h)/2;’>i = (g+h)/2;

[c, f, i]