Add angle snapping to better support circular analog sticks

custom/mupen64plus-core/plugin/emulate_game_controller_via_libretro.c

@@ -32,6 +32,10 @@
 
 #define ROUND(x)    floor((x) + 0.5)
 
+#ifndef  M_PI
+#define  M_PI  3.1415926535897932384626433
+#endif
+
 /* snprintf not available in MSVC 2010 and earlier */
 #include "api/msvc_compat.h"
 
@@ -42,6 +46,9 @@ extern int pad_pak_types[4];
 extern int pad_present[4];
 extern int astick_deadzone;
 extern int astick_sensitivity;
+extern int astick_snap_active;
+extern int astick_snap_max_angle;
+extern int astick_snap_min_displacement_percent;
 extern int r_cbutton;
 extern int l_cbutton;
 extern int d_cbutton;
@@ -277,10 +284,9 @@ EXPORT void CALL inputControllerCommand(int Control, unsigned char *Command)
 #define CSTICK_UP 0x800
 #define CSTICK_DOWN 0x400
 
-
 static void inputGetKeys_reuse(int16_t analogX, int16_t analogY, int Control, BUTTONS* Keys)
 {
-   double radius, angle;
+   double radius, angle, circular_degrees, difference, nearest_45;
    //  Keys->Value |= input_cb(Control, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_XX)    ? 0x4000 : 0; // Mempak switch
    //  Keys->Value |= input_cb(Control, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_XX)    ? 0x8000 : 0; // Rumblepak switch
 
@@ -295,6 +301,17 @@ static void inputGetKeys_reuse(int16_t analogX, int16_t analogY, int Control, BU
    {
       // Re-scale analog stick range to negate deadzone (makes slow movements possible)
       radius = (radius - astick_deadzone)*((float)ASTICK_MAX/(ASTICK_MAX - astick_deadzone));
+
+      // Angle Snapping for beter support of circular design controllers
+      if (astick_snap_active) {
+         circular_degrees = (int)(ROUND(angle * (180.0/M_PI)));
+         nearest_45 = round(circular_degrees / 45.0) * 45.0;
+         difference = fabs(circular_degrees - nearest_45);
+         if (difference <= astick_snap_max_angle && (100*(radius / ASTICK_MAX)) >= astick_snap_min_displacement_percent) {
+            angle = nearest_45 * (M_PI / 180.0);
+         }
+      }
+
       // N64 Analog stick range is from -80 to 80
       radius *= 80.0 / ASTICK_MAX * (astick_sensitivity / 100.0);
       // Convert back to cartesian coordinates

libretro/libretro.c

@@ -118,6 +118,9 @@ cothread_t retro_thread;
 
 int astick_deadzone;
 int astick_sensitivity;
+int astick_snap_active;
+int astick_snap_max_angle;
+int astick_snap_min_displacement_percent;
 int r_cbutton;
 int l_cbutton;
 int d_cbutton;
@@ -1384,6 +1387,33 @@ static void update_variables(bool startup)
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
           astick_sensitivity = atoi(var.value);
 
+      var.key = CORE_NAME "-astick-snap-angle-active";
+      var.value = NULL;
+
+      if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+      {
+         if (!strcmp(var.value, "enabled"))
+            astick_snap_active = 1;
+         else if (!strcmp(var.value, "disabled"))
+            astick_snap_active = 0;
+      }
+
+      var.key = CORE_NAME "-astick-snap-max-angle";
+      var.value = NULL;
+
+      if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+      {
+         astick_snap_max_angle = (int)(atoi(var.value));
+      }
+
+      var.key = CORE_NAME "-astick-snap-min-displacement-percent";
+      var.value = NULL;
+
+      if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+      {
+         astick_snap_min_displacement_percent = (int)(atoi(var.value));
+      }
+
        var.key = CORE_NAME "-CountPerOp";
        var.value = NULL;
        if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)

libretro/libretro_core_options.h

@@ -1580,6 +1580,80 @@ struct retro_core_option_v2_definition option_defs_us[] = {
         },
         "100"
     },
+    {
+        CORE_NAME "-astick-snap-angle-active",
+        "Snap Analog Stick Angle to Cardinal Directions",
+        NULL,
+        "Should the analog stick snap to a cardinal direction to better support circular design controllers",
+        NULL,
+        "input",
+        {
+            {"enabled", NULL},
+            {"disabled", NULL},
+            { NULL, NULL },
+        },
+        "disabled"
+    },
+    {
+        CORE_NAME "-astick-snap-max-angle",
+        "Maximum Snap Angle",
+        NULL,
+        "Up to what angle difference should the controller snap to the next cardinal direction. Example: Set to 5 will snap values from 85 to 95 degrees to 90",
+        NULL,
+        "input",
+        {
+            {"1", NULL},
+            {"2", NULL},
+            {"3", NULL},
+            {"4", NULL},
+            {"5", NULL},
+            {"6", NULL},
+            {"7", NULL},
+            {"8", NULL},
+            {"9", NULL},
+            {"10", NULL},
+            {"11", NULL},
+            {"12", NULL},
+            {"13", NULL},
+            {"14", NULL},
+            {"15", NULL},
+            {"16", NULL},
+            {"17", NULL},
+            {"18", NULL},
+            {"19", NULL},
+            {"20", NULL},
+            {"21", NULL},
+            { NULL, NULL },
+        },
+        "15"
+    },
+    {
+        CORE_NAME "-astick-snap-min-displacement-percent",
+        "Which percentage of displacement causes snap to activate",
+        NULL,
+        "To closely emulate the behaviour of classic, notched controllers, angle snapping \
+        can be activated only when the analog stick is displaced far enough from the center position, zero means always, even on slow movement",
+        NULL,
+        "input",
+        {
+            {"0", NULL},
+            {"10", NULL},
+            {"20", NULL},
+            {"30", NULL},
+            {"40", NULL},
+            {"50", NULL},
+            {"60", NULL},
+            {"65", NULL},
+            {"70", NULL},
+            {"75", NULL},
+            {"80", NULL},
+            {"85", NULL},
+            {"90", NULL},
+            {"95", NULL},
+            { NULL, NULL },
+        },
+        "70"
+    },
     {
         CORE_NAME "-r-cbutton",
         "Right C Button",