SyncedTransform uses local scale

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1

Hi the DragControls component seems to be changing worldScale when using the MultiTouchDragHandler but the SyncedTransform is sending a local scale. As a result when I adjust the scale of an object the scale change wont propagate to other devices. Is this intended behaviour?

2

Hi Gilderko,

The behavior you’re observing where the DragControls component modifies the world scale while SyncedTransform uses the local scale is indeed significant in a networking context. In your case, if the DragControls is impacting the world scale and SyncedTransform is shipping local scale changes, this discrepancy would prevent correct scaling synchronization across multiple clients.

This behavior appears to be by design, as SyncedTransform is generally intended to manage only local transformations to maintain coherence across devices. However, if the scale should also sync across devices, adjustments would be necessary.

To resolve this, you’ll want to consider either:

  1. Modifying the SyncedTransform to include the world scale when broadcasting its state.
  2. Alternatively, ensure the DragControls processes scale in the same local reference frame if you want changes to be reflected correctly across clients.

You may also want to examine both components to identify where the synchronization processes diverge and check parameters that might assist in smoothing out this functionality.

For more details, you can refer to the Synced Transform documentation to understand how it handles data (see the documentation), and you may review the DragControls implementation as well (see the documentation).

If you have further information or code snippets, feel free to share them for more specific guidance!

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3

Hello,

SyncedTransform does currently not send any scale. This was - at the time - to keep messages smaller and has not been changed yet for backwards compatibility since it would require to update the binary layout (SyncTransform messages are sent using flatbuffers for performance reasons).

You need to add a custom component that syncs scale in that case.

import { Behaviour, syncField, Vec3 } from "@needle-tools/engine";

export class SyncScale extends Behaviour {

    @syncField(SyncScale.prototype.onRemoteScaleChanged)
    private lastScale!: Vec3;

    awake() {
        this.lastScale = { x: 0, y: 0, z: 0 };
    }

    update() {
        const scale = this.gameObject.scale; // alternatively this.gameObject.worldScale;
        if (!scale.equals(this.lastScale)) {
            this.lastScale.x = scale.x;
            this.lastScale.y = scale.y;
            this.lastScale.z = scale.z;
            this.lastScale = this.lastScale; // re-assign to trigger sync transform update
        }
    }

    private onRemoteScaleChanged(newScale: Vec3) {
        this.gameObject.scale.set(newScale.x, newScale.y, newScale.z);
    }

}
4

This is the SyncedTransform code there is scale in its Flatbuffer.

image
image2560×1279 156 KB

5

Looking into it

Edit: Thanks for the headsup, looks like scale was just not used by SyncedTransform, I should have checked again before replying. Will add this for the next alpha release

1 Like
6

Hi, just wanted to let you know that the latest alpha already has the changes if you want to try

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