From 8dbb03114dd9628303b6be691142a0517f7b688f Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Thu, 16 Oct 2014 21:16:12 -0700
Subject: [PATCH] Improve axis scaling algorithm to fix cardinal direction
 issues

---
 .../nvstream/input/ControllerPacket.java      | 82 +++++++++----------
 .../src/com/limelight/utils/Vector2d.java     | 47 +++++++++++
 2 files changed, 85 insertions(+), 44 deletions(-)
 create mode 100644 moonlight-common/src/com/limelight/utils/Vector2d.java

diff --git a/moonlight-common/src/com/limelight/nvstream/input/ControllerPacket.java b/moonlight-common/src/com/limelight/nvstream/input/ControllerPacket.java
index fc3078cc..f1ca1d13 100644
--- a/moonlight-common/src/com/limelight/nvstream/input/ControllerPacket.java
+++ b/moonlight-common/src/com/limelight/nvstream/input/ControllerPacket.java
@@ -3,6 +3,8 @@ package com.limelight.nvstream.input;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
+import com.limelight.utils.Vector2d;
+
 public class ControllerPacket extends InputPacket {
 		public static final byte[] HEADER =
 			{
@@ -47,11 +49,7 @@ public class ControllerPacket extends InputPacket {
 				InputPacket.HEADER_LENGTH;
 		
 		// This is the highest value that is read as zero on the PC
-		public static final short ABS_LS_OFFSET = 7000;
-		public static final short ABS_RS_OFFSET = 7000;
-		
-		public static final double ABS_LS_SCALE_FACTOR = 1 - (ABS_LS_OFFSET / 32768.0);
-		public static final double ABS_RS_SCALE_FACTOR = 1 - (ABS_RS_OFFSET / 32768.0);
+		public static final short MIN_MAGNITUDE = 7000;
 		
 		// Set this flag if you want ControllerPacket to handle scaling for you
 		// Note: You MUST properly handle deadzones to use this flag
@@ -74,51 +72,47 @@ public class ControllerPacket extends InputPacket {
 			this.buttonFlags = buttonFlags;
 			this.leftTrigger = leftTrigger;
 			this.rightTrigger = rightTrigger;
-			this.leftStickX = scaleLeftStickAxis(leftStickX);
-			this.leftStickY = scaleLeftStickAxis(leftStickY);
-			this.rightStickX = scaleRightStickAxis(rightStickX);
-			this.rightStickY = scaleRightStickAxis(rightStickY);
+			
+			Vector2d leftStick = handleDeadZone(leftStickX, leftStickY);
+			this.leftStickX = (short) leftStick.getX();
+			this.leftStickY = (short) leftStick.getY();
+			
+			Vector2d rightStick = handleDeadZone(rightStickX, rightStickY);
+			this.rightStickX = (short) rightStick.getX();
+			this.rightStickY = (short) rightStick.getY();
 		}
 		
-		private static short scaleAxis(int axisValue, short offset, double factor) {
-			// Exit quit if it's zero
-			if (axisValue == 0) {
-				return 0;
-			}
-			
-			// Remember the sign and remove it from the value
-			int sign = axisValue < 0 ? -1 : 1;
-			axisValue = Math.abs(axisValue);
-			
-			// Scale the initial value
-			axisValue = (int)(axisValue * factor);
-			
-			// Add the offset
-			axisValue += offset;
-			
-			// Correct the value if it's over the limit
-			if (axisValue > 32767) {
-				axisValue = 32767;
-			}
-			
-			// Restore sign and return
-			return (short)(sign * axisValue);
-		}
+		private static Vector2d inputVector = new Vector2d();
+		private static Vector2d normalizedInputVector = new Vector2d();
 		
-		private static short scaleLeftStickAxis(short axisValue) {
+		// This function is NOT THREAD SAFE!
+		private static Vector2d handleDeadZone(short x, short y) {
+			// Get out fast if we're in the dead zone
+			if (x == 0 && y == 0) {
+				return Vector2d.ZERO;
+			}
+			
+			// Reinitialize our cached Vector2d object
+			inputVector.initialize(x, y);
+			
 			if (enableAxisScaling) {
-				axisValue = scaleAxis(axisValue, ABS_LS_OFFSET, ABS_LS_SCALE_FACTOR);
+				// Remember our original magnitude for scaling later
+				double magnitude = inputVector.getMagnitude();
+				
+				// Scale to hit a minimum magnitude
+				inputVector.getNormalized(normalizedInputVector);
+				
+				normalizedInputVector.setX(normalizedInputVector.getX() * MIN_MAGNITUDE);
+				normalizedInputVector.setY(normalizedInputVector.getY() * MIN_MAGNITUDE);
+				
+				// Now scale the rest of the way
+				normalizedInputVector.scalarMultiply((32766.0 / MIN_MAGNITUDE) / (32768.0 / magnitude));
+				
+				return normalizedInputVector;
 			}
-			
-			return axisValue;
-		}
-		
-		private static short scaleRightStickAxis(short axisValue) {
-			if (enableAxisScaling) {
-				axisValue = scaleAxis(axisValue, ABS_RS_OFFSET, ABS_RS_SCALE_FACTOR);
+			else {
+				return inputVector;
 			}
-			
-			return axisValue;
 		}
 
 		@Override
diff --git a/moonlight-common/src/com/limelight/utils/Vector2d.java b/moonlight-common/src/com/limelight/utils/Vector2d.java
new file mode 100644
index 00000000..d01b78ba
--- /dev/null
+++ b/moonlight-common/src/com/limelight/utils/Vector2d.java
@@ -0,0 +1,47 @@
+package com.limelight.utils;
+
+public class Vector2d {
+	private float x;
+	private float y;
+	private double magnitude;
+	
+	public static final Vector2d ZERO = new Vector2d();
+	
+	public Vector2d() {
+		initialize(0, 0);
+	}
+	
+	public void initialize(float x, float y) {
+		this.x = x;
+		this.y = y;
+		this.magnitude = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
+	}
+	
+	public double getMagnitude() {
+		return magnitude;
+	}
+	
+	public void getNormalized(Vector2d vector) {
+		vector.initialize((float)(x / magnitude), (float)(y / magnitude));
+	}
+	
+	public void scalarMultiply(double factor) {
+		initialize((float)(x * factor), (float)(y * factor));
+	}
+	
+	public void setX(float x) {
+		initialize(x, this.y);
+	}
+	
+	public void setY(float y) {
+		initialize(this.x, y);
+	}
+	
+	public float getX() {
+		return x;
+	}
+	
+	public float getY() {
+		return y;
+	}
+}