ArcRotateCamera setPosition behavior different in 2.3

[satguru]

Any reason why this check for equal position was added in 2.3

https://github.com/BabylonJS/Babylon.js/blob/master/src/Cameras/babylon.arcRotateCamera.ts#L492

This changes the behavior subtly

In 2.2 if I wanted to change the target but keep the same position I would save the current position, change the target and do setPosition() using the saved current position.

This would have resulted in the alpha, beta ,radius being re-calculated based on the new target while keeping the same position.

In 2.3 because of the above check all this is bypassed.

 

 

[GameMonetize]

Hum I did not think about this case.

I updated the code to be more convenient:

        public rebuildAnglesAndRadius() {
            var radiusv3 = this.position.subtract(this._getTargetPosition());
            this.radius = radiusv3.length();

            // Alpha
            this.alpha = Math.acos(radiusv3.x / Math.sqrt(Math.pow(radiusv3.x, 2) + Math.pow(radiusv3.z, 2)));

            if (radiusv3.z < 0) {
                this.alpha = 2 * Math.PI - this.alpha;
            }

            // Beta
            this.beta = Math.acos(radiusv3.y / this.radius);

            this._checkLimits();
        }

        public setPosition(position: Vector3): void {
            if (this.position.equals(position)) {
                return;
            }
            this.rebuildAnglesAndRadius();
        }

        public setTarget(target: Vector3): void {
            if (this.target.equals(target)) {
                return;
            }
            this.rebuildAnglesAndRadius();
        }

Now you can just set the target and this should be enough

[satguru]

maybe setPosition()

        public setPosition(position: Vector3): void {
            if (this.position.equals(position)) {
                return;
            }
            this.position = position;
            this.rebuildAnglesAndRadius();
        }

Also if you change setTarget() won't that break other people existing code?

[GameMonetize]

Nope  (Do you feel how sure I am? :))

 

Changes are done btw

[satguru]

5 hours ago, Deltakosh said:

Nope  (Do you feel how sure I am? :))

 

I will trust you on this 

Thanks for the change. Much conveneint for me now.

[satguru]

Maybe I was too trusting 

Looks like the new setTarget() breaks the SceneLoader.load().

Now when a scene is loaded the arc camera does not move to the target. 

See

https://github.com/BabylonJS/Babylon.js/blob/master/src/Cameras/babylon.camera.ts#L693

 

[GameMonetize]

I do not reproduce. Do you have a sample scene?

[satguru]

see attached html.

It uses babylonjs 2.4

it has a simple scene with ground, box and sphere.

The camera targets sphere's position

It has 2 buttons  "save" and "load" - "save" serializes, "load" loads the serialized data.

To test,

• open the file in browser,
• click save then
• click load.

Notice the camera position has changed

Now comment out the following line 

https://github.com/BabylonJS/Babylon.js/blob/master/src/Cameras/babylon.arcRotateCamera.ts#L526

and try again.

behaves as expected the second time.

index.html

[GameMonetize]

Do you have a way to reproduce it on the playground

[satguru]

@Deltakosh

hard to do this on playground

tried anyway. see

http://www.babylonjs-playground.com/#1LQGCI

behaves weird - after load the arc camera turns into a free camera !!

[GameMonetize]

This is an awful bug...I'll fix it soon

[GameMonetize]

Fixed: https://github.com/BabylonJS/Babylon.js/commit/ada2eb7f678c664ac28638b5a2b15f1775aa0aa9

[satguru]

@Deltakosh

Much better now

Now that , that problem is fixed , you can see the the original problem.

I modified the PG demo slightly.

It was hard to see the issue in the original demo, because the camera radius was very large.

So I changed the radius from 50 to 5.

http://www.babylonjs-playground.com/#1LQGCI#1

You can clearly see the problem now, when you do "save" and then "load"

[GameMonetize]

Working on it:)

[GameMonetize]

Fixed

[satguru]

Great! Thanks