PaperMC/paper-server/nms-patches/net/minecraft/world/level/Explosion.patch

--- a/net/minecraft/world/level/Explosion.java
+++ b/net/minecraft/world/level/Explosion.java
@@ -43,6 +43,14 @@
 import net.minecraft.world.phys.MovingObjectPosition;
 import net.minecraft.world.phys.Vec3D;
 
+// CraftBukkit start
+import net.minecraft.world.entity.item.EntityFallingBlock;
+import org.bukkit.craftbukkit.event.CraftEventFactory;
+import org.bukkit.event.entity.EntityExplodeEvent;
+import org.bukkit.Location;
+import org.bukkit.event.block.BlockExplodeEvent;
+// CraftBukkit end
+
 public class Explosion {
 
     private static final ExplosionDamageCalculator EXPLOSION_DAMAGE_CALCULATOR = new ExplosionDamageCalculator();
@@ -61,6 +69,7 @@
     private final ExplosionDamageCalculator damageCalculator;
     private final List<BlockPosition> toBlow;
     private final Map<EntityHuman, Vec3D> hitPlayers;
+    public boolean wasCanceled = false; // CraftBukkit - add field
 
     public Explosion(World world, @Nullable Entity entity, double d0, double d1, double d2, float f) {
         this(world, entity, d0, d1, d2, f, false, Explosion.Effect.DESTROY);
@@ -85,7 +94,7 @@
         this.hitPlayers = Maps.newHashMap();
         this.level = world;
         this.source = entity;
-        this.radius = f;
+        this.radius = (float) Math.max(f, 0.0); // CraftBukkit - clamp bad values
         this.x = d0;
         this.y = d1;
         this.z = d2;
@@ -135,6 +144,11 @@
     }
 
     public void a() {
+        // CraftBukkit start
+        if (this.radius < 0.1F) {
+            return;
+        }
+        // CraftBukkit end
         this.level.a(this.source, GameEvent.EXPLODE, new BlockPosition(this.x, this.y, this.z));
         Set<BlockPosition> set = Sets.newHashSet();
         boolean flag = true;
@@ -174,7 +188,7 @@
                                 f -= ((Float) optional.get() + 0.3F) * 0.3F;
                             }
 
-                            if (f > 0.0F && this.damageCalculator.a(this, this.level, blockposition, iblockdata, f)) {
+                            if (f > 0.0F && this.damageCalculator.a(this, this.level, blockposition, iblockdata, f) && blockposition.getY() < 256 && blockposition.getY() >= 0) { // CraftBukkit - don't wrap explosions
                                 set.add(blockposition);
                             }
 
@@ -218,7 +232,16 @@
                         double d12 = (double) a(vec3d, entity);
                         double d13 = (1.0D - d7) * d12;
 
-                        entity.damageEntity(this.b(), (float) ((int) ((d13 * d13 + d13) / 2.0D * 7.0D * (double) f2 + 1.0D)));
+                        // CraftBukkit start
+                        // entity.damageEntity(this.b(), (float) ((int) ((d13 * d13 + d13) / 2.0D * 7.0D * (double) f2 + 1.0D)));
+                        CraftEventFactory.entityDamage = source;
+                        entity.forceExplosionKnockback = false;
+                        boolean wasDamaged = entity.damageEntity(this.b(), (float) ((int) ((d13 * d13 + d13) / 2.0D * 7.0D * (double) f2 + 1.0D)));
+                        CraftEventFactory.entityDamage = null;
+                        if (!wasDamaged && !(entity instanceof EntityTNTPrimed || entity instanceof EntityFallingBlock) && !entity.forceExplosionKnockback) {
+                            continue;
+                        }
+                        // CraftBukkit end
                         double d14 = d13;
 
                         if (entity instanceof EntityLiving) {
@@ -260,6 +283,51 @@
 
             Collections.shuffle(this.toBlow, this.level.random);
             Iterator iterator = this.toBlow.iterator();
+            // CraftBukkit start
+            org.bukkit.World bworld = this.level.getWorld();
+            org.bukkit.entity.Entity explode = this.source == null ? null : this.source.getBukkitEntity();
+            Location location = new Location(bworld, this.x, this.y, this.z);
+
+            List<org.bukkit.block.Block> blockList = Lists.newArrayList();
+            for (int i1 = this.toBlow.size() - 1; i1 >= 0; i1--) {
+                BlockPosition cpos = (BlockPosition) this.toBlow.get(i1);
+                org.bukkit.block.Block bblock = bworld.getBlockAt(cpos.getX(), cpos.getY(), cpos.getZ());
+                if (!bblock.getType().isAir()) {
+                    blockList.add(bblock);
+                }
+            }
+
+            boolean cancelled;
+            List<org.bukkit.block.Block> bukkitBlocks;
+            float yield;
+
+            if (explode != null) {
+                EntityExplodeEvent event = new EntityExplodeEvent(explode, location, blockList, this.blockInteraction == Explosion.Effect.DESTROY ? 1.0F / this.radius : 1.0F);
+                this.level.getCraftServer().getPluginManager().callEvent(event);
+                cancelled = event.isCancelled();
+                bukkitBlocks = event.blockList();
+                yield = event.getYield();
+            } else {
+                BlockExplodeEvent event = new BlockExplodeEvent(location.getBlock(), blockList, this.blockInteraction == Explosion.Effect.DESTROY ? 1.0F / this.radius : 1.0F);
+                this.level.getCraftServer().getPluginManager().callEvent(event);
+                cancelled = event.isCancelled();
+                bukkitBlocks = event.blockList();
+                yield = event.getYield();
+            }
+
+            this.toBlow.clear();
+
+            for (org.bukkit.block.Block bblock : bukkitBlocks) {
+                BlockPosition coords = new BlockPosition(bblock.getX(), bblock.getY(), bblock.getZ());
+                toBlow.add(coords);
+            }
+
+            if (cancelled) {
+                this.wasCanceled = true;
+                return;
+            }
+            // CraftBukkit end
+            iterator = this.toBlow.iterator();
 
             while (iterator.hasNext()) {
                 BlockPosition blockposition = (BlockPosition) iterator.next();
@@ -274,8 +342,8 @@
                         TileEntity tileentity = iblockdata.isTileEntity() ? this.level.getTileEntity(blockposition) : null;
                         LootTableInfo.Builder loottableinfo_builder = (new LootTableInfo.Builder((WorldServer) this.level)).a(this.level.random).set(LootContextParameters.ORIGIN, Vec3D.a((BaseBlockPosition) blockposition)).set(LootContextParameters.TOOL, ItemStack.EMPTY).setOptional(LootContextParameters.BLOCK_ENTITY, tileentity).setOptional(LootContextParameters.THIS_ENTITY, this.source);
 
-                        if (this.blockInteraction == Explosion.Effect.DESTROY) {
-                            loottableinfo_builder.set(LootContextParameters.EXPLOSION_RADIUS, this.radius);
+                        if (this.blockInteraction == Explosion.Effect.DESTROY || yield < 1.0F) { // CraftBukkit - add yield
+                            loottableinfo_builder.set(LootContextParameters.EXPLOSION_RADIUS, 1.0F / yield); // CraftBukkit - add yield
                         }
 
                         iblockdata.a(loottableinfo_builder).forEach((itemstack) -> {
@@ -305,7 +373,11 @@
                 BlockPosition blockposition2 = (BlockPosition) iterator1.next();
 
                 if (this.random.nextInt(3) == 0 && this.level.getType(blockposition2).isAir() && this.level.getType(blockposition2.down()).i(this.level, blockposition2.down())) {
-                    this.level.setTypeUpdate(blockposition2, BlockFireAbstract.a((IBlockAccess) this.level, blockposition2));
+                    // CraftBukkit start - Ignition by explosion
+                    if (!org.bukkit.craftbukkit.event.CraftEventFactory.callBlockIgniteEvent(this.level, blockposition2.getX(), blockposition2.getY(), blockposition2.getZ(), this).isCancelled()) {
+                        this.level.setTypeUpdate(blockposition2, BlockFireAbstract.a((IBlockAccess) this.level, blockposition2));
+                    }
+                    // CraftBukkit end
                 }
             }
         }
@@ -313,6 +385,7 @@
     }
 
     private static void a(ObjectArrayList<Pair<ItemStack, BlockPosition>> objectarraylist, ItemStack itemstack, BlockPosition blockposition) {
+        if (itemstack.isEmpty()) return; // CraftBukkit - SPIGOT-5425
         int i = objectarraylist.size();
 
         for (int j = 0; j < i; ++j) {