Inconsistent animation duration with mesh.getAbsolutePosition()

Bugs
#1

I am trying to animate a mesh from its current position to a target position over the period of several dozen seconds. I have been using mesh.getAbsolutePosition() in order to get the starting position for the animation keys, but the duration/speed of the animation is accelerated considerably when doing this, and I’ve been unable to decipher why?

PG: https://playground.babylonjs.com/#X6RG4E#5

If instead, I just use the (in this case) knwon starting position of new Vector(0,0,0) then the duration of the animation is correct.

Any assistance would be most welcome.

Thanks

#2

Just noticed that the animation duration defaults to 1 second when using getAbsolutePosition()

#3

Just to clear up a misunderstanding engine.getFps() refers to the rendering frame rate used by Babylon.js and this is not the same as the animation frame rate which you fix for yourself.

frames per second - number , the number of animation frames per second (independent of the scene rendering frames per second)

from The Animation Method | Babylon.js Documentation

So if you have 100 animation frames that you want to render of 6 seconds the frame rate is 100 / 6

and the frame count goes from 0 to 100.

The other point is about using absolutePosition.
This PG uses the position of the sphere and as it has a parent it is the position of the sphere relative to its parent (see line 31) https://playground.babylonjs.com/#X6RG4E#7

This PG uses absolutePosition https://playground.babylonjs.com/#X6RG4E#8

See how the sphere jumps. In

let sphereMove = new BABYLON.Animation("sphereMove",
      "position",
      FRAME_RATE,
      BABYLON.Animation.ANIMATIONTYPE_VECTOR3,
      BABYLON.Animation.ANIMATIONLOOPMODE_CONSTANT);

Your start point is the absolutePosition of the sphere but it is the sphere’s position not absolutePosition that is being updated within the animation.

As far I I know there is not a parameteryou can add for absolutePosition in BABYLON.Animation

1 Like
#4

Thank you for the great clarification John