Fix for #2327 Mouse pointer moves to centre of canvas on click in OpenGL3 with Swing

[terranprog]

Modify FlyByCamera to only hide the mouse cursor when the user actually rotates the camera, rather than when the user first presses the left mouse button. When the mouse is clicked, instead of immediately hiding the cursor, a flag (hideCursorOnNextRotate) is set. If and when a rotate is detected, the flag is checked and if true the cursor is hidden and the flag is cleared.

[capdevon]

I tested the behavior of FlyByCamera with LWJGL2 and LWJGL3 in combination with Swing. In both cases, setting flyCam.setDragToRotate(true) repositions the mouse pointer to the center of the Canvas after the left mouse button is released to enable camera rotation. This behavior does not occur in typical applications that do not use Swing, where the mouse pointer returns to its last position at the time of the click.

While this isn’t overly inconvenient and you can get used to it, it’s worth noting that FlyByCamera is built into the SimpleApplication class by default and is likely used by thousands of applications. Changing its behavior could introduce more problems than benefits without extensive testing. FlyByCamera was probably not designed specifically for use with Swing, but rather for simple JME applications.

If your goal is to develop an editor with Java Swing + JME, I recommend creating a custom EditorCamera by duplicating the FlyByCamera code and adapting it to your specific needs. JME is designed to be customizable in almost all of its components.

[codex128]

If these changes introduce functionally different behaviors (particularly on glfw applications), I'd suggest adding an option to disable or enable the changes, with it disabled by default.

Also, I don't foresee there being any problems, but it would be good to make sure nothing unexpected happens when using glfw with any opengl versions along with these changes.

[codex128]

Change to } else { (one line)

[codex128]

This could be changed to

if (!canRotate) {
    return;
} else if (hideCursorOnNextRotate) {
    inputManager.setCursorVisible(false);
    hideCursorOnNextRotate = false;
}