From f5b6abfae1377905e6fc2c46e36dfe2279c48b2b Mon Sep 17 00:00:00 2001
From: Wesley Wolfe <weswolf@aol.com>
Date: Sat, 23 Jun 2012 08:31:01 -0500
Subject: [PATCH] Fix double overflow/underflow calculations with explosions.
 Fixes BUKKIT-1865

---
 .../java/net/minecraft/server/Explosion.java  | 27 ++++++++++++-------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/main/java/net/minecraft/server/Explosion.java b/src/main/java/net/minecraft/server/Explosion.java
index e4ba32070e..c1582f66bf 100644
--- a/src/main/java/net/minecraft/server/Explosion.java
+++ b/src/main/java/net/minecraft/server/Explosion.java
@@ -108,17 +108,26 @@ public class Explosion {
 
         for (int k2 = 0; k2 < list.size(); ++k2) {
             Entity entity = (Entity) list.get(k2);
-            double d7 = entity.f(this.posX, this.posY, this.posZ) / (double) this.size;
+            // CraftBukkit - start
+            d0 = entity.locX - this.posX;
+            d1 = entity.locY - this.posY;
+            d2 = entity.locZ - this.posZ;
+            double d8 = Math.sqrt(d0 * d0 + d1 * d1 + d2 * d2);
+
+            double d7 = d8 / this.size; // Don't call sub-method and sqrt again
 
             if (d7 <= 1.0D) {
-                d0 = entity.locX - this.posX;
-                d1 = entity.locY - this.posY;
-                d2 = entity.locZ - this.posZ;
-                double d8 = Math.sqrt(d0 * d0 + d1 * d1 + d2 * d2); // CraftBukkit
-
-                d0 /= d8;
-                d1 /= d8;
-                d2 /= d8;
+                // Moved calculations up
+                if (d8 != 0) {
+                    d0 /= d8;
+                    d1 /= d8;
+                    d2 /= d8;
+                } else { // Compensate for underflow
+                    d0 = 0d;
+                    d1 = 0d;
+                    d2 = 0d;
+                }
+                // CraftBukkit - end
                 double d9 = (double) this.world.a(vec3d, entity.boundingBox);
                 double d10 = (1.0D - d7) * d9;