ArcRotateCamera move camera with target

christopheC · December 15, 2020, 12:38pm

Hi everyone!

I’m trying to do something which I thought would be simple but that I’m surprisingly struggling with…
I’m animating an arcRotateCamera target with CreateAndStartAnimation.

The target moves as expected but I would like to “lock” the alpha, beta and radius of my camera or link it to the target so that when the target moves, the camera moves in parrallel.
I made a playground based on the ArcRotateCamera to test it out.
https://playground.babylonjs.com/#SRZRWV#404
When you press the space bar, the camera target will move towards the blue plane but the camera is not moving which currently makes sense.
I tried animating the alpha, beta, radius but that doesn’t seem to work. I tried to parent the camera to the target but Babylon doesn’t like it which also makes sense.

Let me know if you can think about anything else.

Thanks in advance for your help!

Chris

Gijs · December 15, 2020, 4:58pm

Hi Chris,

Animating “_target” instead of “target” works in the PG, maybe it would work in your project as well:

“target” is a setter, and it calls this function:

github.com

BabylonJS/Babylon.js/blob/master/src/Cameras/arcRotateCamera.ts#L1030


    this.rebuildAnglesAndRadius();
}

/**
 * Defines the target the camera should look at.
 * This will automatically adapt alpha beta and radius to fit within the new target.
 * @param target Defines the new target as a Vector or a mesh
 * @param toBoundingCenter In case of a mesh target, defines whether to target the mesh position or its bounding information center
 * @param allowSamePosition If false, prevents reapplying the new computed position if it is identical to the current one (optim)
 */
public setTarget(target: AbstractMesh | Vector3, toBoundingCenter = false, allowSamePosition = false): void {
    if ((<any>target).getBoundingInfo) {
        if (toBoundingCenter) {
            this._targetBoundingCenter = (<any>target).getBoundingInfo().boundingBox.centerWorld.clone();
        } else {
            this._targetBoundingCenter = null;
        }
        (<AbstractMesh>target).computeWorldMatrix();
        this._targetHost = <AbstractMesh>target;
        this._target = this._getTargetPosition();

I don’t know if there’s a proper way to do this.

christopheC · December 15, 2020, 5:02pm

Well that was even easier than I thought Thanks so much for your help.

Thanks so much for your help!

Chris

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ArcRotateCamera move camera with target

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