Is there any way to predict the relative position between two meshes?

Questions
1

In this example, Example of Camera | Babylon.js Playground (babylonjs.com) [Wrong example, what I need is position of mesh need to change]

The thing I need to achieve is for example, the start position of mesh A is (1, 0, 0), the position of B is (2, 1, 0), so there are some relative position between A and B, when A change its position, is it possible to know where B should be, if the relative position does not change?

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2

@pigga I have some trouble to understand what you are trying to achieve ?

The planes do not move in your example, nor loaded dynamically. More details would be great.

3

@bghgary might have an explanation :slight_smile: basically here the planes do not move at all only the camera is, so you do not need to predict anything, just use the same position for the second plane.

4

Ah, you’re right, should found some better playground examples, the thing I need to achieve is for example, the start position of mesh A is (1, 0, 0), the position of B is (2, 1, 0), so there are some relative position between A and B, when A change its position, is it possible to know where B should be, if the relative position does not change?

5

just do B.setParent(A) on start and they will move together

6

The problem I have now is these two mesh does not load at the same time, so I can’t just setParent, only when A stop moving, B will start to load (need to be put on the relative position of A)

7

so just use A.parent = B and set the relative position you need on A.

8

Could you explain more what do you mean that “set the relative position you need on A”, why use A.parent = B, should that be B.parent = A?

9

If you know the starting positions then I think you could subtract A’s starting position from B’s starting position to calculate what B’s local position should be.

b.parent = a;
b.position = bStartPosition.subtract(aStartPosition);
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10

@pigga the other approach you can take is if you know the required offset between A and B, you can just update the position of B in scene.onBeforeRenderObservable to be B.position = A.position + offset. And if you need to keep the relative position to A when B loads but is determined by the current position of A when B finishes loading, you can then determine in the callback of the loader offset = B.position - A.position and then use that value in scene.onBeforeRenderObservable.

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11

yup totally meant B.parent = A, my bad… it s friday :slight_smile:

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12

Hello @pigga just checking in, was your question answered?

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