Fix #5231

Fix #5234
Fix #5237

src/Cameras/babylon.camera.ts

@@ -780,7 +780,7 @@
             if (!origin) {
                 origin = this.position;
             }
-            var forward = new Vector3(0, 0, 1);
+            var forward = this._scene.useRightHandedSystem ? new Vector3(0, 0, -1) : new Vector3(0, 0, 1);
             var forwardWorld = Vector3.TransformNormal(forward, transform);
 
             var direction = Vector3.Normalize(forwardWorld);

src/Cameras/babylon.targetCamera.ts

@@ -350,6 +350,7 @@
         }
 
         private _cachedRotationZ = 0;
+        private _cachedQuaternionRotationZ = 0;
         /** @hidden */
         public _getViewMatrix(): Matrix {
             if (this.lockedTarget) {
@@ -359,8 +360,11 @@
             // Compute
             this._updateCameraRotationMatrix();
 
-            // Apply the changed rotation to the upVector.
-            if (this._cachedRotationZ != this.rotation.z) {
+            // Apply the changed rotation to the upVector
+            if (this.rotationQuaternion && this._cachedQuaternionRotationZ != this.rotationQuaternion.z) {
+                this._rotateUpVectorWithCameraRotationMatrix();
+                this._cachedQuaternionRotationZ = this.rotationQuaternion.z;
+            } else if (this._cachedRotationZ != this.rotation.z) {
                 this._rotateUpVectorWithCameraRotationMatrix();
                 this._cachedRotationZ = this.rotation.z;
             }

src/Materials/babylon.shaderMaterial.ts

@@ -111,7 +111,7 @@
          * @returns a boolean specifying if alpha blending is needed
          */
         public needAlphaBlending(): boolean {
-            return (this.alpha < 1.0);
+            return (this.alpha < 1.0) || this._options.needAlphaBlending;
         }
 
         /**