From f16f6209402ab43846255aabbbce6e4dbfca6197 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 854ad49b6c..3ee310a9aa 100644
--- a/src/main/java/net/minecraft/server/EnumDirection.java
+++ b/src/main/java/net/minecraft/server/EnumDirection.java
@@ -85,6 +85,7 @@ public enum EnumDirection implements INamable {
         return this.i;
     }
 
+    public final EnumDirection.EnumAxisDirection getAxisDirection() { return c(); } // Paper - OBFHELPER
     public EnumDirection.EnumAxisDirection c() {
         return this.l;
     }
@@ -93,6 +94,7 @@ public enum EnumDirection implements INamable {
         return fromType1(this.h);
     }
 
+    public final EnumDirection rotateY() { return e(); } // Paper - OBFHELPER
     public EnumDirection e() {
         switch (this) {
         case NORTH:
@@ -272,6 +274,7 @@ public enum EnumDirection implements INamable {
             this.d = s;
         }
 
+        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 f52b9c6f0a..3adbfb8209 100644
--- a/src/main/java/net/minecraft/server/MathHelper.java
+++ b/src/main/java/net/minecraft/server/MathHelper.java
@@ -82,6 +82,7 @@ public class MathHelper {
         return f < f1 ? f1 : (f > f2 ? f2 : f);
     }
 
+    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) {
         return d0 < d1 ? d1 : (d0 > d2 ? d2 : d0);
     }
diff --git a/src/main/java/net/minecraft/server/PortalTravelAgent.java b/src/main/java/net/minecraft/server/PortalTravelAgent.java
index 7444f4621e..16ca3209cd 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 3faf74a22f..4e1f8c211d 100644
--- a/src/main/java/net/minecraft/server/ShapeDetector.java
+++ b/src/main/java/net/minecraft/server/ShapeDetector.java
@@ -140,6 +140,7 @@ public class ShapeDetector {
             return this.c;
         }
 
+        public final int getWidth() { return this.d(); } // Paper - OBFHELPER
         public int d() {
             return this.e;
         }
-- 
2.18.0