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-rw-r--r--patches/server/1036-Actually-optimise-explosions.patch521
1 files changed, 521 insertions, 0 deletions
diff --git a/patches/server/1036-Actually-optimise-explosions.patch b/patches/server/1036-Actually-optimise-explosions.patch
new file mode 100644
index 0000000000..349e2e5f06
--- /dev/null
+++ b/patches/server/1036-Actually-optimise-explosions.patch
@@ -0,0 +1,521 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Spottedleaf <[email protected]>
+Date: Tue, 12 Sep 2023 06:50:16 -0700
+Subject: [PATCH] Actually optimise explosions
+
+The vast majority of blocks an explosion of power ~4 tries
+to destroy are duplicates. The core of the block destroying
+part of this patch is to cache the block state, resistance, and
+whether it should explode - as those will not change.
+
+The other part of this patch is to optimise the visibility
+percentage calculation. The new visibility calculation takes
+advantage of the block caching already done by the explosion logic.
+It continues to update the cache as the visibility calculation
+uses many rays which can overlap significantly.
+
+Effectively, the patch uses a lot of caching to eliminate
+redundant operations.
+
+Performance benchmarking explosions is challenging, as it varies
+depending on the power, the number of nearby entities, and the
+nearby terrain. This means that no benchmark can cover all the cases.
+I decided to test a giant block of TNT, as that's where the optimisations
+would be needed the most.
+
+I tested using a 50x10x50 block of TNT above ground
+and determined the following:
+
+Vanilla time per explosion: 2.27ms
+Lithium time per explosion: 1.07ms
+This patch time per explosion: 0.45ms
+
+The results indicate that this logic is 5 times faster than Vanilla
+and 2.3 times faster than Lithium.
+
+diff --git a/src/main/java/net/minecraft/world/level/Explosion.java b/src/main/java/net/minecraft/world/level/Explosion.java
+index 4d51baab29b1a913c3efef2cb4ab0cac6c8cf38a..1fa02130dcb65b3109fde0cb612b538b1c4cd4cb 100644
+--- a/src/main/java/net/minecraft/world/level/Explosion.java
++++ b/src/main/java/net/minecraft/world/level/Explosion.java
+@@ -111,6 +111,271 @@ public class Explosion {
+ this.yield = this.blockInteraction == Explosion.BlockInteraction.DESTROY_WITH_DECAY ? 1.0F / this.radius : 1.0F; // CraftBukkit
+ }
+
++ // Paper start - optimise collisions
++ private static final double[] CACHED_RAYS;
++ static {
++ final it.unimi.dsi.fastutil.doubles.DoubleArrayList rayCoords = new it.unimi.dsi.fastutil.doubles.DoubleArrayList();
++
++ for (int x = 0; x <= 15; ++x) {
++ for (int y = 0; y <= 15; ++y) {
++ for (int z = 0; z <= 15; ++z) {
++ if ((x == 0 || x == 15) || (y == 0 || y == 15) || (z == 0 || z == 15)) {
++ double xDir = (double)((float)x / 15.0F * 2.0F - 1.0F);
++ double yDir = (double)((float)y / 15.0F * 2.0F - 1.0F);
++ double zDir = (double)((float)z / 15.0F * 2.0F - 1.0F);
++
++ double mag = Math.sqrt(
++ xDir * xDir + yDir * yDir + zDir * zDir
++ );
++
++ rayCoords.add((xDir / mag) * (double)0.3F);
++ rayCoords.add((yDir / mag) * (double)0.3F);
++ rayCoords.add((zDir / mag) * (double)0.3F);
++ }
++ }
++ }
++ }
++
++ CACHED_RAYS = rayCoords.toDoubleArray();
++ }
++
++ private static final int CHUNK_CACHE_SHIFT = 2;
++ private static final int CHUNK_CACHE_MASK = (1 << CHUNK_CACHE_SHIFT) - 1;
++ private static final int CHUNK_CACHE_WIDTH = 1 << CHUNK_CACHE_SHIFT;
++
++ private static final int BLOCK_EXPLOSION_CACHE_SHIFT = 3;
++ private static final int BLOCK_EXPLOSION_CACHE_MASK = (1 << BLOCK_EXPLOSION_CACHE_SHIFT) - 1;
++ private static final int BLOCK_EXPLOSION_CACHE_WIDTH = 1 << BLOCK_EXPLOSION_CACHE_SHIFT;
++
++ // resistance = (res + 0.3F) * 0.3F;
++ // so for resistance = 0, we need res = -0.3F
++ private static final Float ZERO_RESISTANCE = Float.valueOf(-0.3f);
++ private it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap<ExplosionBlockCache> blockCache = null;
++
++ public static final class ExplosionBlockCache {
++
++ public final long key;
++ public final BlockPos immutablePos;
++ public final BlockState blockState;
++ public final FluidState fluidState;
++ public final float resistance;
++ public final boolean outOfWorld;
++ public Boolean shouldExplode; // null -> not called yet
++ public net.minecraft.world.phys.shapes.VoxelShape cachedCollisionShape;
++
++ public ExplosionBlockCache(long key, BlockPos immutablePos, BlockState blockState, FluidState fluidState, float resistance,
++ boolean outOfWorld) {
++ this.key = key;
++ this.immutablePos = immutablePos;
++ this.blockState = blockState;
++ this.fluidState = fluidState;
++ this.resistance = resistance;
++ this.outOfWorld = outOfWorld;
++ }
++ }
++
++ private long[] chunkPosCache = null;
++ private net.minecraft.world.level.chunk.LevelChunk[] chunkCache = null;
++
++ private ExplosionBlockCache getOrCacheExplosionBlock(final int x, final int y, final int z,
++ final long key, final boolean calculateResistance) {
++ ExplosionBlockCache ret = this.blockCache.get(key);
++ if (ret != null) {
++ return ret;
++ }
++
++ BlockPos pos = new BlockPos(x, y, z);
++
++ if (!this.level.isInWorldBounds(pos)) {
++ ret = new ExplosionBlockCache(key, pos, null, null, 0.0f, true);
++ } else {
++ net.minecraft.world.level.chunk.LevelChunk chunk;
++ long chunkKey = io.papermc.paper.util.CoordinateUtils.getChunkKey(x >> 4, z >> 4);
++ int chunkCacheKey = ((x >> 4) & CHUNK_CACHE_MASK) | (((z >> 4) << CHUNK_CACHE_SHIFT) & (CHUNK_CACHE_MASK << CHUNK_CACHE_SHIFT));
++ if (this.chunkPosCache[chunkCacheKey] == chunkKey) {
++ chunk = this.chunkCache[chunkCacheKey];
++ } else {
++ this.chunkPosCache[chunkCacheKey] = chunkKey;
++ this.chunkCache[chunkCacheKey] = chunk = this.level.getChunk(x >> 4, z >> 4);
++ }
++
++ BlockState blockState = chunk.getBlockStateFinal(x, y, z);
++ FluidState fluidState = blockState.getFluidState();
++
++ Optional<Float> resistance = !calculateResistance ? Optional.empty() : this.damageCalculator.getBlockExplosionResistance((Explosion)(Object)this, this.level, pos, blockState, fluidState);
++
++ ret = new ExplosionBlockCache(
++ key, pos, blockState, fluidState,
++ (resistance.orElse(ZERO_RESISTANCE).floatValue() + 0.3f) * 0.3f,
++ false
++ );
++ }
++
++ this.blockCache.put(key, ret);
++
++ return ret;
++ }
++
++ private boolean clipsAnything(final Vec3 from, final Vec3 to,
++ final io.papermc.paper.util.CollisionUtil.LazyEntityCollisionContext context,
++ final ExplosionBlockCache[] blockCache,
++ final BlockPos.MutableBlockPos currPos) {
++ // assume that context.delegated = false
++ final double adjX = io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON * (from.x - to.x);
++ final double adjY = io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON * (from.y - to.y);
++ final double adjZ = io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON * (from.z - to.z);
++
++ if (adjX == 0.0 && adjY == 0.0 && adjZ == 0.0) {
++ return false;
++ }
++
++ final double toXAdj = to.x - adjX;
++ final double toYAdj = to.y - adjY;
++ final double toZAdj = to.z - adjZ;
++ final double fromXAdj = from.x + adjX;
++ final double fromYAdj = from.y + adjY;
++ final double fromZAdj = from.z + adjZ;
++
++ int currX = Mth.floor(fromXAdj);
++ int currY = Mth.floor(fromYAdj);
++ int currZ = Mth.floor(fromZAdj);
++
++ final double diffX = toXAdj - fromXAdj;
++ final double diffY = toYAdj - fromYAdj;
++ final double diffZ = toZAdj - fromZAdj;
++
++ final double dxDouble = Math.signum(diffX);
++ final double dyDouble = Math.signum(diffY);
++ final double dzDouble = Math.signum(diffZ);
++
++ final int dx = (int)dxDouble;
++ final int dy = (int)dyDouble;
++ final int dz = (int)dzDouble;
++
++ final double normalizedDiffX = diffX == 0.0 ? Double.MAX_VALUE : dxDouble / diffX;
++ final double normalizedDiffY = diffY == 0.0 ? Double.MAX_VALUE : dyDouble / diffY;
++ final double normalizedDiffZ = diffZ == 0.0 ? Double.MAX_VALUE : dzDouble / diffZ;
++
++ double normalizedCurrX = normalizedDiffX * (diffX > 0.0 ? (1.0 - Mth.frac(fromXAdj)) : Mth.frac(fromXAdj));
++ double normalizedCurrY = normalizedDiffY * (diffY > 0.0 ? (1.0 - Mth.frac(fromYAdj)) : Mth.frac(fromYAdj));
++ double normalizedCurrZ = normalizedDiffZ * (diffZ > 0.0 ? (1.0 - Mth.frac(fromZAdj)) : Mth.frac(fromZAdj));
++
++ for (;;) {
++ currPos.set(currX, currY, currZ);
++
++ // ClipContext.Block.COLLIDER -> BlockBehaviour.BlockStateBase::getCollisionShape
++ // ClipContext.Fluid.NONE -> ignore fluids
++
++ // read block from cache
++ final long key = BlockPos.asLong(currX, currY, currZ);
++
++ final int cacheKey =
++ (currX & BLOCK_EXPLOSION_CACHE_MASK) |
++ (currY & BLOCK_EXPLOSION_CACHE_MASK) << (BLOCK_EXPLOSION_CACHE_SHIFT) |
++ (currZ & BLOCK_EXPLOSION_CACHE_MASK) << (BLOCK_EXPLOSION_CACHE_SHIFT + BLOCK_EXPLOSION_CACHE_SHIFT);
++ ExplosionBlockCache cachedBlock = blockCache[cacheKey];
++ if (cachedBlock == null || cachedBlock.key != key) {
++ blockCache[cacheKey] = cachedBlock = this.getOrCacheExplosionBlock(currX, currY, currZ, key, false);
++ }
++
++ final BlockState blockState = cachedBlock.blockState;
++ if (blockState != null && !blockState.emptyCollisionShape()) {
++ net.minecraft.world.phys.shapes.VoxelShape collision = cachedBlock.cachedCollisionShape;
++ if (collision == null) {
++ collision = blockState.getConstantCollisionShape();
++ if (collision == null) {
++ collision = blockState.getCollisionShape(this.level, currPos, context);
++ if (!context.isDelegated()) {
++ // if it was not delegated during this call, assume that for any future ones it will not be delegated
++ // again, and cache the result
++ cachedBlock.cachedCollisionShape = collision;
++ }
++ } else {
++ cachedBlock.cachedCollisionShape = collision;
++ }
++ }
++
++ if (!collision.isEmpty() && collision.clip(from, to, currPos) != null) {
++ return true;
++ }
++ }
++
++ if (normalizedCurrX > 1.0 && normalizedCurrY > 1.0 && normalizedCurrZ > 1.0) {
++ return false;
++ }
++
++ // inc the smallest normalized coordinate
++
++ if (normalizedCurrX < normalizedCurrY) {
++ if (normalizedCurrX < normalizedCurrZ) {
++ currX += dx;
++ normalizedCurrX += normalizedDiffX;
++ } else {
++ // x < y && x >= z <--> z < y && z <= x
++ currZ += dz;
++ normalizedCurrZ += normalizedDiffZ;
++ }
++ } else if (normalizedCurrY < normalizedCurrZ) {
++ // y <= x && y < z
++ currY += dy;
++ normalizedCurrY += normalizedDiffY;
++ } else {
++ // y <= x && z <= y <--> z <= y && z <= x
++ currZ += dz;
++ normalizedCurrZ += normalizedDiffZ;
++ }
++ }
++ }
++
++ private float getSeenFraction(final Vec3 source, final Entity target,
++ final ExplosionBlockCache[] blockCache,
++ final BlockPos.MutableBlockPos blockPos) {
++ final AABB boundingBox = target.getBoundingBox();
++ final double diffX = boundingBox.maxX - boundingBox.minX;
++ final double diffY = boundingBox.maxY - boundingBox.minY;
++ final double diffZ = boundingBox.maxZ - boundingBox.minZ;
++
++ final double incX = 1.0 / (diffX * 2.0 + 1.0);
++ final double incY = 1.0 / (diffY * 2.0 + 1.0);
++ final double incZ = 1.0 / (diffZ * 2.0 + 1.0);
++
++ if (incX < 0.0 || incY < 0.0 || incZ < 0.0) {
++ return 0.0f;
++ }
++
++ final double offX = (1.0 - Math.floor(1.0 / incX) * incX) * 0.5 + boundingBox.minX;
++ final double offY = boundingBox.minY;
++ final double offZ = (1.0 - Math.floor(1.0 / incZ) * incZ) * 0.5 + boundingBox.minZ;
++
++ final io.papermc.paper.util.CollisionUtil.LazyEntityCollisionContext context = new io.papermc.paper.util.CollisionUtil.LazyEntityCollisionContext(target);
++
++ int totalRays = 0;
++ int missedRays = 0;
++
++ for (double dx = 0.0; dx <= 1.0; dx += incX) {
++ final double fromX = Math.fma(dx, diffX, offX);
++ for (double dy = 0.0; dy <= 1.0; dy += incY) {
++ final double fromY = Math.fma(dy, diffY, offY);
++ for (double dz = 0.0; dz <= 1.0; dz += incZ) {
++ ++totalRays;
++
++ final Vec3 from = new Vec3(
++ fromX,
++ fromY,
++ Math.fma(dz, diffZ, offZ)
++ );
++
++ if (!this.clipsAnything(from, source, context, blockCache, blockPos)) {
++ ++missedRays;
++ }
++ }
++ }
++ }
++
++ return (float)missedRays / (float)totalRays;
++ }
++ // Paper end - optimise collisions
++
+ private ExplosionDamageCalculator makeDamageCalculator(@Nullable Entity entity) {
+ return (ExplosionDamageCalculator) (entity == null ? Explosion.EXPLOSION_DAMAGE_CALCULATOR : new EntityBasedExplosionDamageCalculator(entity));
+ }
+@@ -171,40 +436,88 @@ public class Explosion {
+ int i;
+ int j;
+
+- for (int k = 0; k < 16; ++k) {
+- for (i = 0; i < 16; ++i) {
+- for (j = 0; j < 16; ++j) {
+- if (k == 0 || k == 15 || i == 0 || i == 15 || j == 0 || j == 15) {
+- double d0 = (double) ((float) k / 15.0F * 2.0F - 1.0F);
+- double d1 = (double) ((float) i / 15.0F * 2.0F - 1.0F);
+- double d2 = (double) ((float) j / 15.0F * 2.0F - 1.0F);
+- double d3 = Math.sqrt(d0 * d0 + d1 * d1 + d2 * d2);
+-
+- d0 /= d3;
+- d1 /= d3;
+- d2 /= d3;
++ // Paper start - optimise explosions
++ this.blockCache = new it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap<>();
++
++ this.chunkPosCache = new long[CHUNK_CACHE_WIDTH * CHUNK_CACHE_WIDTH];
++ java.util.Arrays.fill(this.chunkPosCache, ChunkPos.INVALID_CHUNK_POS);
++
++ this.chunkCache = new net.minecraft.world.level.chunk.LevelChunk[CHUNK_CACHE_WIDTH * CHUNK_CACHE_WIDTH];
++
++ final ExplosionBlockCache[] blockCache = new ExplosionBlockCache[BLOCK_EXPLOSION_CACHE_WIDTH * BLOCK_EXPLOSION_CACHE_WIDTH * BLOCK_EXPLOSION_CACHE_WIDTH];
++ // use initial cache value that is most likely to be used: the source position
++ final ExplosionBlockCache initialCache;
++ {
++ final int blockX = Mth.floor(this.x);
++ final int blockY = Mth.floor(this.y);
++ final int blockZ = Mth.floor(this.z);
++
++ final long key = BlockPos.asLong(blockX, blockY, blockZ);
++
++ initialCache = this.getOrCacheExplosionBlock(blockX, blockY, blockZ, key, true);
++ }
++ // only ~1/3rd of the loop iterations in vanilla will result in a ray, as it is iterating the perimeter of
++ // a 16x16x16 cube
++ // we can cache the rays and their normals as well, so that we eliminate the excess iterations / checks and
++ // calculations in one go
++ // additional aggressive caching of block retrieval is very significant, as at low power (i.e tnt) most
++ // block retrievals are not unique
++ for (int ray = 0, len = CACHED_RAYS.length; ray < len;) {
++ {
++ {
++ {
++ ExplosionBlockCache cachedBlock = initialCache;
++
++ double d0 = CACHED_RAYS[ray];
++ double d1 = CACHED_RAYS[ray + 1];
++ double d2 = CACHED_RAYS[ray + 2];
++ ray += 3;
++ // Paper end - optimise explosions
+ float f = this.radius * (0.7F + this.level.random.nextFloat() * 0.6F);
+ double d4 = this.x;
+ double d5 = this.y;
+ double d6 = this.z;
+
+ for (float f1 = 0.3F; f > 0.0F; f -= 0.22500001F) {
+- BlockPos blockposition = BlockPos.containing(d4, d5, d6);
+- BlockState iblockdata = this.level.getBlockState(blockposition);
+- if (!iblockdata.isDestroyable()) continue; // Paper - Protect Bedrock and End Portal/Frames from being destroyed
+- FluidState fluid = iblockdata.getFluidState(); // Paper - Perf: Optimize call to getFluid for explosions
++ // Paper start - optimise explosions
++ final int blockX = Mth.floor(d4);
++ final int blockY = Mth.floor(d5);
++ final int blockZ = Mth.floor(d6);
++
++ final long key = BlockPos.asLong(blockX, blockY, blockZ);
++
++ if (cachedBlock.key != key) {
++ final int cacheKey =
++ (blockX & BLOCK_EXPLOSION_CACHE_MASK) |
++ (blockY & BLOCK_EXPLOSION_CACHE_MASK) << (BLOCK_EXPLOSION_CACHE_SHIFT) |
++ (blockZ & BLOCK_EXPLOSION_CACHE_MASK) << (BLOCK_EXPLOSION_CACHE_SHIFT + BLOCK_EXPLOSION_CACHE_SHIFT);
++ cachedBlock = blockCache[cacheKey];
++ if (cachedBlock == null || cachedBlock.key != key) {
++ blockCache[cacheKey] = cachedBlock = this.getOrCacheExplosionBlock(blockX, blockY, blockZ, key, true);
++ }
++ }
+
+- if (!this.level.isInWorldBounds(blockposition)) {
++ if (cachedBlock.outOfWorld) {
+ break;
+ }
+
+- Optional<Float> optional = this.damageCalculator.getBlockExplosionResistance(this, this.level, blockposition, iblockdata, fluid);
++ BlockPos blockposition = cachedBlock.immutablePos;
++ BlockState iblockdata = cachedBlock.blockState;
++ // Paper end - optimise explosions
+
+- if (optional.isPresent()) {
+- f -= ((Float) optional.get() + 0.3F) * 0.3F;
+- }
++ if (!iblockdata.isDestroyable()) continue; // Paper
++ // Paper - optimise explosions
+
+- if (f > 0.0F && this.damageCalculator.shouldBlockExplode(this, this.level, blockposition, iblockdata, f)) {
++ f -= cachedBlock.resistance; // Paper - optimise explosions
++
++ if (f > 0.0F && cachedBlock.shouldExplode == null) { // Paper - optimise explosions
++ // Paper start - optimise explosions
++ // note: we expect shouldBlockExplode to be pure with respect to power, as Vanilla currently is.
++ // basically, it is unused, which allows us to cache the result
++ final boolean shouldExplode = this.damageCalculator.shouldBlockExplode(this, this.level, cachedBlock.immutablePos, cachedBlock.blockState, f);
++ cachedBlock.shouldExplode = shouldExplode ? Boolean.TRUE : Boolean.FALSE;
++ if (shouldExplode && (this.fire || !cachedBlock.blockState.isAir())) {
++ // Paper end - optimise explosions
+ set.add(blockposition);
+ // Paper start - prevent headless pistons from forming
+ if (!io.papermc.paper.configuration.GlobalConfiguration.get().unsupportedSettings.allowHeadlessPistons && iblockdata.getBlock() == Blocks.MOVING_PISTON) {
+@@ -215,11 +528,12 @@ public class Explosion {
+ }
+ }
+ // Paper end - prevent headless pistons from forming
++ } // Paper - optimise explosions
+ }
+
+- d4 += d0 * 0.30000001192092896D;
+- d5 += d1 * 0.30000001192092896D;
+- d6 += d2 * 0.30000001192092896D;
++ d4 += d0; // Paper - optimise explosions
++ d5 += d1; // Paper - optimise explosions
++ d6 += d2; // Paper - optimise explosions
+ }
+ }
+ }
+@@ -239,6 +553,8 @@ public class Explosion {
+ Vec3 vec3d = new Vec3(this.x, this.y, this.z);
+ Iterator iterator = list.iterator();
+
++ final BlockPos.MutableBlockPos blockPos = new BlockPos.MutableBlockPos(); // Paper - optimise explosions
++
+ while (iterator.hasNext()) {
+ Entity entity = (Entity) iterator.next();
+
+@@ -275,11 +591,11 @@ public class Explosion {
+ for (EnderDragonPart entityComplexPart : ((EnderDragon) entity).subEntities) {
+ // Calculate damage separately for each EntityComplexPart
+ if (list.contains(entityComplexPart)) {
+- entityComplexPart.hurt(this.damageSource, this.damageCalculator.getEntityDamageAmount(this, entity));
++ entityComplexPart.hurt(this.damageSource, this.damageCalculator.getEntityDamageAmount(this, entityComplexPart, getSeenFraction(vec3d, entityComplexPart, blockCache, blockPos))); // Paper - actually optimise explosions and use the right entity to calculate the damage
+ }
+ }
+ } else {
+- entity.hurt(this.damageSource, this.damageCalculator.getEntityDamageAmount(this, entity));
++ entity.hurt(this.damageSource, this.damageCalculator.getEntityDamageAmount(this, entity, getSeenFraction(vec3d, entity, blockCache, blockPos))); // Paper - actually optimise explosions
+ }
+
+ CraftEventFactory.entityDamage = null;
+@@ -289,7 +605,7 @@ public class Explosion {
+ // CraftBukkit end
+ }
+
+- double d12 = (1.0D - d7) * this.getBlockDensity(vec3d, entity); // Paper - Optimize explosions
++ double d12 = (1.0D - d7) * this.getBlockDensity(vec3d, entity, blockCache, blockPos); // Paper - Optimize explosions
+ double d13;
+
+ if (entity instanceof LivingEntity) {
+@@ -318,6 +634,9 @@ public class Explosion {
+ }
+ }
+
++ this.blockCache = null; // Paper - optimise explosions
++ this.chunkPosCache = null; // Paper - optimise explosions
++ this.chunkCache = null; // Paper - optimise explosions
+ }
+
+ public void finalizeExplosion(boolean particles) {
+@@ -531,14 +850,14 @@ public class Explosion {
+ private BlockInteraction() {}
+ }
+ // Paper start - Optimize explosions
+- private float getBlockDensity(Vec3 vec3d, Entity entity) {
++ private float getBlockDensity(Vec3 vec3d, Entity entity, ExplosionBlockCache[] blockCache, BlockPos.MutableBlockPos blockPos) { // Paper - optimise explosions
+ if (!this.level.paperConfig().environment.optimizeExplosions) {
+- return getSeenPercent(vec3d, entity);
++ return this.getSeenFraction(vec3d, entity, blockCache, blockPos); // Paper - optimise explosions
+ }
+ CacheKey key = new CacheKey(this, entity.getBoundingBox());
+ Float blockDensity = this.level.explosionDensityCache.get(key);
+ if (blockDensity == null) {
+- blockDensity = getSeenPercent(vec3d, entity);
++ blockDensity = this.getSeenFraction(vec3d, entity, blockCache, blockPos); // Paper - optimise explosions;
+ this.level.explosionDensityCache.put(key, blockDensity);
+ }
+
+diff --git a/src/main/java/net/minecraft/world/level/ExplosionDamageCalculator.java b/src/main/java/net/minecraft/world/level/ExplosionDamageCalculator.java
+index 24dba1eb6f5dc71e5d1ce2d150930eaefc83f811..f529f5d0f28533ec89f3ee712e59745991d068ee 100644
+--- a/src/main/java/net/minecraft/world/level/ExplosionDamageCalculator.java
++++ b/src/main/java/net/minecraft/world/level/ExplosionDamageCalculator.java
+@@ -20,11 +20,17 @@ public class ExplosionDamageCalculator {
+ return true;
+ }
+
++ @io.papermc.paper.annotation.DoNotUse @Deprecated // Paper
+ public float getEntityDamageAmount(Explosion explosion, Entity entity) {
++ // Paper start - actually optimise explosions
++ return this.getEntityDamageAmount(explosion, entity, Explosion.getSeenPercent(explosion.center(), entity));
++ }
++ public float getEntityDamageAmount(Explosion explosion, Entity entity, double seenPercent) {
++ // Paper end - actually optimise explosions
+ float f = explosion.radius() * 2.0F;
+ Vec3 vec3 = explosion.center();
+ double d = Math.sqrt(entity.distanceToSqr(vec3)) / (double)f;
+- double e = (1.0D - d) * (double)Explosion.getSeenPercent(vec3, entity);
++ double e = (1.0D - d) * seenPercent; // Paper - actually optimise explosions
+ return (float)((e * e + e) / 2.0D * 7.0D * (double)f + 1.0D);
+ }
+ }