possible fix for rare(ish) mouselook subpixel bug (#64)

Author: gmriggs

ACViewer/Extensions/MouseEx.cs

@@ -0,0 +1,28 @@
+using System.Runtime.InteropServices;
+using System.Windows;
+using System.Windows.Media;
+
+namespace ACViewer.Extensions
+{
+    public class MouseEx
+    {
+        public struct POINT
+        {
+            public int X;
+            public int Y;
+        }
+
+        [DllImport("user32.dll")]
+        public static extern bool GetCursorPos(out POINT lpPoint);
+
+        [DllImport("user32.dll")]
+        public static extern bool SetCursorPos(int X, int Y);
+
+        public static Point SetCursor(Visual visual, int x, int y)
+        {
+            var p = visual.PointToScreen(new Point(x, y));
+            SetCursorPos((int)p.X, (int)p.Y);
+            return p;
+        }
+    }
+}

ACViewer/Player.cs

@@ -147,6 +147,8 @@ public static bool GetKeyState(KeyboardState keyboardState, List<Keys> keys)
 
         private static readonly float MouseSpeedBase = 0.5f / 6.0f;
 
+        public System.Windows.Point LastSetPoint { get; set; }
+
         public void Update(GameTime time)
         {
             if (!FullSim)
@@ -283,8 +285,10 @@ public void Update(GameTime time)
             {
                 if (wasRightClick)
                 {
-                    var diffX = mouseState.X - Camera.centerX;
-                    var diffY = mouseState.Y - Camera.centerY;
+                    MouseEx.GetCursorPos(out var cursorPos);
+
+                    var diffX = cursorPos.X - (int)LastSetPoint.X;
+                    var diffY = cursorPos.Y - (int)LastSetPoint.Y;
 
                     if (ConfigManager.Config.Mouse.AltMethod)
                     {
@@ -324,7 +328,7 @@ public void Update(GameTime time)
                 }
 
                 if (!ConfigManager.Config.Mouse.AltMethod)
-                    Mouse.SetCursor(Camera.centerX, Camera.centerY);
+                    LastSetPoint = MouseEx.SetCursor(GameView.Instance, Camera.centerX, Camera.centerY);
             }
             else if (wasRightClick)
             {

ACViewer/Render/Camera.cs

@@ -11,6 +11,7 @@
 
 using ACViewer.Config;
 using ACViewer.Enum;
+using ACViewer.Extensions;
 using ACViewer.Render;
 using ACViewer.View;
 
@@ -273,6 +274,8 @@ public Matrix CreateProjection()
 
         public bool Locked { get; set; }
 
+        public System.Windows.Point LastSetPoint { get; set; }
+
         public void Update(GameTime gameTime)
         {
             if (Mouse == null || Locked) return;
@@ -314,8 +317,10 @@ public void Update(GameTime gameTime)
             {
                 if (PrevMouseState.RightButton == ButtonState.Pressed)
                 {
-                    var xDiff = mouseState.X - centerX;
-                    var yDiff = mouseState.Y - centerY;
+                    MouseEx.GetCursorPos(out var cursorPos);
+                    
+                    var xDiff = cursorPos.X - (int)LastSetPoint.X;
+                    var yDiff = cursorPos.Y - (int)LastSetPoint.Y;
 
                     if (ConfigManager.Config.Mouse.AltMethod)
                     {
@@ -345,7 +350,7 @@ public void Update(GameTime gameTime)
                 }
                 // there is a delay here, so Mouse.GetState() won't be immediately affected
                 if (!ConfigManager.Config.Mouse.AltMethod)
-                    Mouse.SetCursor(centerX, centerY);
+                    LastSetPoint = MouseEx.SetCursor(GameView.Instance, centerX, centerY);
             }
             else if (PrevMouseState.RightButton == ButtonState.Pressed)
             {