From 7985be57aba821828054109936465be0cf84d8f1 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Sun, 30 Nov 2014 15:35:20 -0600
Subject: [PATCH] Translate the analog stick values of controllers with
 "square" analog stick planes (DS3, DS4, and others) to the circular plane
 that XInput programs expect

---
 .../binding/input/ControllerHandler.java      | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/app/src/main/java/com/limelight/binding/input/ControllerHandler.java b/app/src/main/java/com/limelight/binding/input/ControllerHandler.java
index c8a8052c..6d9a8396 100644
--- a/app/src/main/java/com/limelight/binding/input/ControllerHandler.java
+++ b/app/src/main/java/com/limelight/binding/input/ControllerHandler.java
@@ -421,12 +421,32 @@ public class ControllerHandler {
 		}
 	}
 
+    private void handleAnalogStickPlaneMapping(ControllerMapping mapping, Vector2d stickVector) {
+        if (!mapping.squareAnalogStick) {
+            // If the stick vector's magnitude exceeds 1.0 (1.1 to be safe), that means
+            // that the stick isn't behaving like a circular analog stick but like a square
+            if (stickVector.getMagnitude() > 1.1f) {
+                mapping.squareAnalogStick = true;
+                LimeLog.info("Switching to square analog stick mode");
+            }
+        }
+
+        if (mapping.squareAnalogStick) {
+            double xSquare = stickVector.getX();
+            double ySquare = stickVector.getY();
+            stickVector.setX((float)(xSquare * Math.sqrt(1.0 - 0.5*Math.abs(ySquare))));
+            stickVector.setY((float)(ySquare * Math.sqrt(1.0 - 0.5*Math.abs(xSquare))));
+        }
+    }
+
     private void handleAxisSet(ControllerMapping mapping, float lsX, float lsY, float rsX,
                                float rsY, float lt, float rt, float hatX, float hatY) {
 
         if (mapping.leftStickXAxis != -1 && mapping.leftStickYAxis != -1) {
             Vector2d leftStickVector = handleDeadZone(lsX, lsY, mapping.leftStickDeadzoneRadius);
 
+            handleAnalogStickPlaneMapping(mapping, leftStickVector);
+
             leftStickX = (short) (leftStickVector.getX() * 0x7FFE);
             leftStickY = (short) (-leftStickVector.getY() * 0x7FFE);
         }
@@ -434,6 +454,8 @@ public class ControllerHandler {
         if (mapping.rightStickXAxis != -1 && mapping.rightStickYAxis != -1) {
             Vector2d rightStickVector = handleDeadZone(rsX, rsY, mapping.rightStickDeadzoneRadius);
 
+            handleAnalogStickPlaneMapping(mapping, rightStickVector);
+
             rightStickX = (short) (rightStickVector.getX() * 0x7FFE);
             rightStickY = (short) (-rightStickVector.getY() * 0x7FFE);
         }
@@ -748,5 +770,9 @@ public class ControllerHandler {
         public boolean backIsStart;
         public boolean isRemote;
         public boolean hasJoystickAxes;
+
+        // XInput uses a rounded analog stick where (1.0, 1.0) -> (2^(1/2), 2^(1/2))
+        // Some controllers have square sticks which we will map onto the circular plane
+        public boolean squareAnalogStick;
 	}
 }