Mouse Warp events are not filtered out from mouse velocity calculations

[madmiraal]

Godot version

3.4.2, 3.5.beta and master 57a057f

System information

Ubuntu 21.10 but confirmed on macOS too

Issue description

When the mouse is warped the instantaneous change in position is not being filtered out for mouse velocity (speed in 3.x) calculations.

On the linuxbsd platform, there is code that is supposed to filter these events, but it doesn't appear to be working:

godot/platform/linuxbsd/display_server_x11.cpp

Lines 3533 to 3556 in 6a3ff8f

	case MotionNotify: {
	// The X11 API requires filtering one-by-one through the motion
	// notify events, in order to figure out which event is the one
	// generated by warping the mouse pointer.
	while (true) {
	if (mouse_mode == MOUSE_MODE_CAPTURED && event.xmotion.x == windows[MAIN_WINDOW_ID].size.width / 2 && event.xmotion.y == windows[MAIN_WINDOW_ID].size.height / 2) {
	//this is likely the warp event since it was warped here
	center = Vector2(event.xmotion.x, event.xmotion.y);
	break;
	}
	if (event_index + 1 < events.size()) {
	const XEvent &next_event = events[event_index + 1];
	if (next_event.type == MotionNotify) {
	++event_index;
	event = next_event;
	} else {
	break;
	}
	} else {
	break;
	}
	}

This is an old issue: see #8414, which was closed even though the issue was still happening. It also happens when the mouse enters the window (the difference between the exit and enter positions are added to the velocity calculation).

Note: #56754 (and it's 3.x version #56755) makes #8414 (MOUSE_MODE_CAPTURED) and the mouse entering the window problem less noticeable, but it's still very noticeable when using Input.warp_mouse_position().

Steps to reproduce

Use Input.warp_mouse_position(), and check Input.get_last_mouse_velocity() (Input.get_last_mouse_speed() on 3.x).

Minimal reproduction project

3.x: MouseWarpSpeed-3.x.zip
4.0: MouseWarpVelocity-4.0.zip

Note: On 4.0, without #56548, #53894 requires the window to be moved, or unfocused and focused again for InputEventMouseMotion events to be received.