if you notice I have camera.speed = 0.3 , which works with keyboard arrow keys, but not with those GUI buttons, when you hover on button camera speed is different, may @Evgeni_Popov has some idea, since he helped me with inputs for this snippet.
@sebavan, @Cedric thanks I just figured what I was doing wrong, I just had to properly scale, I was doing this ( see .scale(0.1)) camera.cameraDirection.addInPlace(camera.getDirection(BABYLON.Vector3.Forward()).scale(0.1));
which I had to scale like below ( see .scale(0.03)) to match with my camera.speed = 0.3; camera.cameraDirection.addInPlace(camera.getDirection(BABYLON.Vector3.Forward()).scale(0.03));