proto/mouse: don't depend on float difference

It underflowed cause of our high dt.

Also get the smallest difference over the screen, for HMD devices.

Allow for very low-sensitivity operation.

Issue: #523

2 files changed, 25 insertions, 47 deletions

diff --git a/proto-mouse/ftnoir_protocol_mouse.cpp b/proto-mouse/ftnoir_protocol_mouse.cpp
index 85b8cf1d..5e8a7bc1 100644
--- a/proto-mouse/ftnoir_protocol_mouse.cpp
+++ b/proto-mouse/ftnoir_protocol_mouse.cpp
@@ -30,22 +30,18 @@ void mouse::pose(const double *headpose)
     if (axis_x >= 0 && axis_x < 6)
     {
         mouse_x = get_value(headpose[axis_x] * invert[axis_x],
-                            last_pos_x,
-                            last_x,
-                            axis_x >= 3,
-                            static_cast<slider_value>(s.sensitivity_x));
+                            s.sensitivity_x(),
+                            axis_x >= 3);
     }
 
     if (axis_y >= 0 && axis_y < 6)
         mouse_y = get_value(headpose[axis_y] * invert[axis_y],
-                            last_pos_y,
-                            last_y,
-                            axis_y >= 3,
-                            static_cast<slider_value>(s.sensitivity_y));
+                            s.sensitivity_y(),
+                            axis_y >= 3);
 
     MOUSEINPUT mi;
-    mi.dx = mouse_x;
-    mi.dy = mouse_y;
+    mi.dx = get_delta(mouse_x, last_x);
+    mi.dy = get_delta(mouse_y, last_y);
     mi.mouseData = 0;
     mi.dwFlags = MOUSEEVENTF_MOVE | MOUSEEVENTF_MOVE_NOCOALESCE;
     mi.time = 0;
@@ -64,45 +60,28 @@ QString mouse::game_name()
     return "Mouse tracker";
 }
 
-double mouse::get_rotation(double val, double last_pos)
+int mouse::get_delta(int val, int prev)
 {
-    using std::fmod;
-    using std::fabs;
-    using std::copysign;
-    using std::min;
-
-    const double x_1 = val - last_pos;
-
-    if (x_1 > 180)
-        return 360 - x_1;
-    else if (x_1 < -180)
-        return 360 + x_1;
-    else
-        return x_1;
+    using std::abs;
+
+    const int a = abs(val - prev), b = abs(val + prev), c = abs(val);
+    if (c < a && c < b)
+        return val;
+    if (b < a && b < c)
+        return val + prev;
+    return val - prev;
 }
 
-int mouse::get_value(double val, double& last_pos, int& last_px, bool is_rotation, double sensitivity)
+int mouse::get_value(double val, double sensitivity, bool is_rotation)
 {
     static constexpr double c = 1e-1;
+    static constexpr double sgn[] = { 1e-2, 1 };
 
-    if (is_rotation)
-    {
-        const double rot_delta = get_rotation(val, last_pos);
-
-        last_pos = val;
-        last_px = int(rot_delta * c * sensitivity);
-    }
-    else
-    {
-        val -= last_pos;
-
-        last_pos = val;
-        last_px = int(val * c * sensitivity / 100 - last_px);
-    }
-
-    return last_px;
+    return iround(val * c * sensitivity * sgn[unsigned(is_rotation)]);
 }
 
+mouse::mouse() : last_x(0), last_y(0) {}
+
 bool mouse::correct()
 {
     return true;
diff --git a/proto-mouse/ftnoir_protocol_mouse.h b/proto-mouse/ftnoir_protocol_mouse.h
index e920c047..4f0bf5a7 100644
--- a/proto-mouse/ftnoir_protocol_mouse.h
+++ b/proto-mouse/ftnoir_protocol_mouse.h
@@ -20,24 +20,23 @@ struct settings : opts {
         opts("mouse-proto"),
         Mouse_X(b, "mouse-x", 0),
         Mouse_Y(b, "mouse-y", 0),
-        sensitivity_x(b, "mouse-sensitivity-x", slider_value(200, 100, 500)),
-        sensitivity_y(b, "mouse-sensitivity-y", slider_value(200, 100, 500))
+        sensitivity_x(b, "mouse-sensitivity-x", slider_value(200, 25, 500)),
+        sensitivity_y(b, "mouse-sensitivity-y", slider_value(200, 25, 500))
     {}
 };
 
 class mouse : public IProtocol
 {
 public:
-    mouse() : last_pos_x(0), last_pos_y(0), last_x(0), last_y(0) {}
+    mouse();
     bool correct() override;
     void pose( const double *headpose) override;
     QString game_name() override;
 
-    double last_pos_x, last_pos_y;
     int last_x, last_y;
 private:
-    static double get_rotation(double val, double last_val);
-    static int get_value(double val, double& last_pos, int& last_px, bool is_rotation, double sensitivity);
+    static int get_delta(int val, int prev);
+    static int get_value(double val, double sensitivity, bool is_rotation);
 
     struct settings s;
 };