From 91c66cede1fe69afa655668cb7a6323884bea06f Mon Sep 17 00:00:00 2001
From: Zach Brown <zach.brown@destroystokyo.com>
Date: Tue, 31 Jul 2018 19:32:57 -0500
Subject: [PATCH] Make portal teleportation adjustment math more accurate


diff --git a/src/main/java/net/minecraft/server/EnumDirection.java b/src/main/java/net/minecraft/server/EnumDirection.java
index c0853f0fc..7aa940672 100644
--- a/src/main/java/net/minecraft/server/EnumDirection.java
+++ b/src/main/java/net/minecraft/server/EnumDirection.java
@@ -95,6 +95,7 @@ public enum EnumDirection implements INamable {
         return this.i;
     }
 
+    public final EnumDirection.EnumAxisDirection getAxisDirection() { return c(); } // Paper - OBFHELPER
     public EnumDirection.EnumAxisDirection c() {
         return this.l;
     }
@@ -103,6 +104,7 @@ public enum EnumDirection implements INamable {
         return fromType1(this.h);
     }
 
+    public final EnumDirection rotateY() { return e(); } // Paper - OBFHELPER
     public EnumDirection e() {
         switch(this) {
         case NORTH:
@@ -333,6 +335,7 @@ public enum EnumDirection implements INamable {
             this.d = s1;
         }
 
+        public final int getOffset() { return a(); } // Paper - OBFHELPER
         public int a() {
             return this.c;
         }
diff --git a/src/main/java/net/minecraft/server/MathHelper.java b/src/main/java/net/minecraft/server/MathHelper.java
index d53d0c242..49fba0979 100644
--- a/src/main/java/net/minecraft/server/MathHelper.java
+++ b/src/main/java/net/minecraft/server/MathHelper.java
@@ -83,6 +83,7 @@ public class MathHelper {
         }
     }
 
+    public static double clamp(double d0, double d1, double d2) { return a(d0, d1, d2); } // Paper - OBFHELPER
     public static double a(double d0, double d1, double d2) {
         if (d0 < d1) {
             return d1;
diff --git a/src/main/java/net/minecraft/server/PortalTravelAgent.java b/src/main/java/net/minecraft/server/PortalTravelAgent.java
index 7e858bab4..eba6eaf37 100644
--- a/src/main/java/net/minecraft/server/PortalTravelAgent.java
+++ b/src/main/java/net/minecraft/server/PortalTravelAgent.java
@@ -208,11 +208,27 @@ public class PortalTravelAgent {
                 ++d4;
             }
 
+            // Paper start - Prevent portal suffocation (and therefore getting teleported up in an attempt to avoid it)
+            // Based on work by CarpetMod - Licensed GPL-3.0
+            double offset = (1.0D - entity.getPortalOffset().x) * (double) shapedetector_shapedetectorcollection.getWidth() * (double) shapedetector_shapedetectorcollection.getFacing().rotateY().getAxisDirection().getOffset();
+            double adjustedRadius = 1.02 * entity.width / 2;
+            if (adjustedRadius >= shapedetector_shapedetectorcollection.getWidth() - adjustedRadius) {
+                // entity wider than portal, place it in the middle
+                adjustedRadius = (double) shapedetector_shapedetectorcollection.getWidth() / 2 - 0.001;
+            }
+
+            if (offset >= 0) {
+                offset = MathHelper.clamp(offset, adjustedRadius, (double) shapedetector_shapedetectorcollection.getWidth() - adjustedRadius);
+            } else {
+                offset = MathHelper.clamp(offset, (double) -shapedetector_shapedetectorcollection.getWidth() + adjustedRadius, -adjustedRadius);
+            }
+
             if (shapedetector_shapedetectorcollection.getFacing().k() == EnumDirection.EnumAxis.X) {
-                d3 = d4 + (1.0D - entity.getPortalOffset().x) * (double) shapedetector_shapedetectorcollection.d() * (double) shapedetector_shapedetectorcollection.getFacing().e().c().a();
+                d3 = d4 + offset;
             } else {
-                d2 = d4 + (1.0D - entity.getPortalOffset().x) * (double) shapedetector_shapedetectorcollection.d() * (double) shapedetector_shapedetectorcollection.getFacing().e().c().a();
+                d2 = d4 + offset;
             }
+            // Paper end
 
             float f1 = 0.0F;
             float f2 = 0.0F;
diff --git a/src/main/java/net/minecraft/server/ShapeDetector.java b/src/main/java/net/minecraft/server/ShapeDetector.java
index 0c9910d9a..446cdb86d 100644
--- a/src/main/java/net/minecraft/server/ShapeDetector.java
+++ b/src/main/java/net/minecraft/server/ShapeDetector.java
@@ -143,6 +143,7 @@ public class ShapeDetector {
             return this.c;
         }
 
+        public final int getWidth() { return this.d(); } // Paper - OBFHELPER
         public int d() {
             return this.e;
         }
-- 
2.20.0