ArcRotateCamera: Modify rotation logic to use invertRotation flag (#1…

…2762)

* Add logic to allow invertRotation to affect ArcRotateCamera

* Moved inverse calls to just one line

* lint/format fix

packages/dev/core/src/Cameras/arcRotateCamera.ts

@@ -911,6 +911,7 @@ export class ArcRotateCamera extends TargetCamera {
         this.inputs.checkInputs();
         // Inertia
         if (this.inertialAlphaOffset !== 0 || this.inertialBetaOffset !== 0 || this.inertialRadiusOffset !== 0) {
+            const directionModifier = this.invertRotation ? -1 : 1;
             let inertialAlphaOffset = this.inertialAlphaOffset;
             if (this.beta <= 0) {
                 inertialAlphaOffset *= -1;
@@ -921,9 +922,9 @@ export class ArcRotateCamera extends TargetCamera {
             if (this.parent && this.parent._getWorldMatrixDeterminant() < 0) {
                 inertialAlphaOffset *= -1;
             }
-            this.alpha += inertialAlphaOffset;
+            this.alpha += inertialAlphaOffset * directionModifier;
 
-            this.beta += this.inertialBetaOffset;
+            this.beta += this.inertialBetaOffset * directionModifier;
 
             this.radius -= this.inertialRadiusOffset;
             this.inertialAlphaOffset *= this.inertia;