# GPUParticleSystem updating position for new particles

**URL:** <https://forum.babylonjs.com/t/gpuparticlesystem-updating-position-for-new-particles/38266>\
**Category:** Questions\
**Created:** [February 15, 2023, 10:39pm UTC](https://forum.babylonjs.com/t/gpuparticlesystem-updating-position-for-new-particles/38266 "2023-02-15T22:39:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![webgrid](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/webgrid/32/24940_2.png) [@webgrid](https://forum.babylonjs.com/u/webgrid)\
**Post date:** [February 15, 2023, 10:39pm UTC](https://forum.babylonjs.com/t/gpuparticlesystem-updating-position-for-new-particles/38266/1 "2023-02-15T22:39:24Z")

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Can you change the `out.z` value for `BABYLON.CustomParticleEmitter` and `particlePositionGenerator` in `GPUParticleSystem` without resetting the particle system when the `activeParticleCount` is increased?

> **[Babylon.js Playground](https://playground.babylonjs.com/#8ZCSHL)**
>
> Babylon.js playground is a live editor for Babylon.js WebGL 3D scenes

Here I increase the activeParticleCount by 250ms intervals, and the particles are added but the I would like to change the out for the new particles foreach interval 🙂

Any suggestions ?

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**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\
**Post date:** [February 16, 2023, 10:25am UTC](https://forum.babylonjs.com/t/gpuparticlesystem-updating-position-for-new-particles/38266/2 "2023-02-16T10:25:26Z")

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Unfortunately, it is not possible to do it with the GPU particle system because the initial positions are generated at start and reused for new particles when other particles are dying.

That’s because everything is running on the GPU, and your `customEmitter.particlePositionGenerator` javascript function can’t be called on the GPU when new particles must be created.