fix jittering when moving the camera around in map editor mode.

This is related to a494a3f411 and should hopefully
fix the last issues with this for good.
Seems fine with SDL versions from 2022 and 2023 on windows;
untested on linux.

(The second window->handleInput() that got removed broke the sing circle
if it was there. It was previously added as a mitigation and is no longer
needed.)

BBGE/Core.cpp

@@ -961,17 +961,18 @@ void Core::resetTimer()
 
 void Core::setMousePosition(const Vector &p)
 {
-	float px = p.x + virtualOffX;
-	float py = p.y;
+	int ix, iy;
+	virtualCoordsToPixelPos(ix, iy, p);
 
 	SDL_Event ev = { sdlUserMouseEventID };
+	ev.motion.x = ix;
+	ev.motion.y = iy;
+	ev.motion.xrel = 0;
+	ev.motion.yrel = 0;
 	ev.motion.state = 0;
 	SDL_PushEvent(&ev);
 
-	window->warpMouse(
-		px * (float(width)/float(virtualWidth)),
-		py * (float(height)/float(virtualHeight))
-	);
+	window->warpMouse(ix, iy);
 
 	ev.motion.state = 1;
 	SDL_PushEvent(&ev);
@@ -1243,12 +1244,12 @@ void Core::setMouseConstraintCircle(const Vector& pos, float circle)
 
 
 
-int Core::getVirtualOffX()
+int Core::getVirtualOffX() const
 {
 	return virtualOffX;
 }
 
-int Core::getVirtualOffY()
+int Core::getVirtualOffY() const
 {
 	return virtualOffY;
 }
@@ -1275,12 +1276,39 @@ bool Core::doMouseConstraint()
 	return false;
 }
 
+Vector Core::pixelPosToVirtualCoords(int x, int y) const
+{
+	const float mx = float(virtualWidth)/float(getWindowWidth());
+	const float my = float(virtualHeight)/float(getWindowHeight());
+
+	return Vector(
+		(x * mx) - getVirtualOffX(),
+		 y * my
+	);
+}
+
+void Core::virtualCoordsToPixelPos(int& x, int& y, const Vector& p)
+{
+	const float px = p.x + getVirtualOffX();
+	const float py = p.y;
+	x = px * (float(getWindowWidth())/float(virtualWidth));
+	y = py * (float(getWindowHeight())/float(virtualHeight));
+}
+
 void Core::onEvent(const SDL_Event& event)
 {
 	const bool focus = window->hasFocus();
 	if(event.type == sdlUserMouseEventID)
 	{
-		mouse._enableMotionEvents = event.motion.state;
+		mouse._enableMotionEvents = !!event.motion.state;
+		if(event.motion.state) // If 1, the generated mouse move is done and the rest is true mouse events
+		{
+			// We just set the position, so lets make sure that this mouse move isn't picked up
+			// as a relative change, ie. there was no actual user mouse move.
+			// There may be regular mouse move events after this one, which will be picked up normally.
+			mouse.lastPosition = pixelPosToVirtualCoords(event.motion.x, event.motion.y);
+			goto motion; // All the needed data are there, use this like a regular motion event
+		}
 		return;
 	}
 
@@ -1320,17 +1348,16 @@ void Core::onEvent(const SDL_Event& event)
 		}
 		break;
 
+		// This event is also sent when SDL sets the mouse position!
+		// Since there's no way to distinguish the generated event from a true "user moved the mouse" event,
+		// sdlUserMouseEventID (above) is used to guard a generated motion event.
 		case SDL_MOUSEMOTION:
 		{
-			if (focus)
+			if (focus && mouse._enableMotionEvents)
 			{
-				const float mx = float(virtualWidth)/float(getWindowWidth());
-				const float my = float(virtualHeight)/float(getWindowHeight());
-
-				mouse.position.x = ((event.motion.x) * mx) - getVirtualOffX();
-				mouse.position.y = event.motion.y * my;
-				if(mouse._enableMotionEvents)
-					mouse._wasMoved = true;
+motion:
+				mouse.position = pixelPosToVirtualCoords(event.motion.x, event.motion.y);
+				mouse._wasMoved = true;
 			}
 		}
 		break;
@@ -1434,10 +1461,7 @@ void Core::pollEvents(float dt)
 	if(mouse._wasMoved)
 	{
 		if(doMouseConstraint())
-		{
 			setMousePosition(mouse.position);
-			window->handleInput();
-		}
 		mouse.change = mouse.position - mouse.lastPosition;
 	}
 

BBGE/Core.h

@@ -233,6 +233,8 @@ public:
 	// state functions
 
 	void setMousePosition(const Vector &p);
+	Vector pixelPosToVirtualCoords(int x, int y) const;
+	void virtualCoordsToPixelPos(int& x, int& y, const Vector& p);
 
 	void setFullscreen(bool full);
 
@@ -384,8 +386,8 @@ public:
 	int getDisplayIndex();
 	int getRefreshRate();
 
-	int getVirtualOffX();
-	int getVirtualOffY();
+	int getVirtualOffX() const;
+	int getVirtualOffY() const;
 
 	void centerMouse();