MC中的爆炸其實挺科學的，在空中爆炸衝擊波傳得遠，破壞範圍比較大；在地面爆炸破壞範圍小但是破壞深度較深
不科學的地方是它的爆炸範圍是正方體，只不過一般範圍小到看不出是正方體。至於爲什麼MOD裏的核彈爆炸範圍是球體，那是別人重新實現了爆炸函數把範圍改掉了…
類名net.minecraft.world.World
/**
* Creates an explosion. Args: entity, x, y, z, strength
*/
public Explosion createExplosion(Entity entityIn, double x, double y, double z, float strength, boolean isSmoking)
{
return this.newExplosion(entityIn, x, y, z, strength, false, isSmoking);
}
/**
* returns a new explosion. Does initiation (at time of writing Explosion is not finished)
*/
// isFlaming影響是否着火，isSmoking影響是否生成粒子和破壞方塊
public Explosion newExplosion(Entity entityIn, double x, double y, double z, float strength, boolean isFlaming, boolean isSmoking)
{
Explosion explosion = new Explosion(this, entityIn, x, y, z, strength, isFlaming, isSmoking);
if (net.minecraftforge.event.ForgeEventFactory.onExplosionStart(this, explosion)) return explosion;
// 第一階段，計算被破壞的方塊，傷害實體
explosion.doExplosionA();
// 第二階段，破壞方塊，生成粒子效果和掉落物
explosion.doExplosionB(true);
return explosion;
}類名net.minecraft.world.Explosion
public Explosion(World worldIn, Entity p_i45754_2_, double p_i45754_3_, double p_i45754_5_, double p_i45754_7_, float size, boolean p_i45754_10_, boolean p_i45754_11_)
{
this.explosionRNG = new Random();
this.affectedBlockPositions = Lists.<BlockPos>newArrayList();
this.playerKnockbackMap = Maps.<EntityPlayer, Vec3>newHashMap();
this.worldObj = worldIn;
this.exploder = p_i45754_2_;
// 就是上面的strength
this.explosionSize = size;
this.explosionX = p_i45754_3_;
this.explosionY = p_i45754_5_;
this.explosionZ = p_i45754_7_;
this.isFlaming = p_i45754_10_;
this.isSmoking = p_i45754_11_;
this.position = new Vec3(explosionX, explosionY, explosionZ);
}
/**
* Does the first part of the explosion (destroy blocks)
*/
public void doExplosionA()
{
Set<BlockPos> blocksToDestroy = Sets.<BlockPos>newHashSet();
// 遍歷16*16*16正方體邊界上各點，從中心向邊界連線，計算是否破壞連線上的方塊
// 由於這裏正方體尺寸寫死了，如果爆炸範圍太大邊界就會有些方塊沒有遍歷到
for (int x = 0; x < 16; ++x)
{
for (int y = 0; y < 16; ++y)
{
for (int z = 0; z < 16; ++z)
{
// 在邊界
if (x == 0 || x == 15 || y == 0 || y == 15 || z == 0 || z == 15)
{
// 這裏只有-1或1兩個取值
double xStep = (double)((float)x / 15.0F * 2.0F - 1.0F);
double yStep = (double)((float)y / 15.0F * 2.0F - 1.0F);
double zStep = (double)((float)z / 15.0F * 2.0F - 1.0F);
// 歸一化
double step = Math.sqrt(xStep * xStep + yStep * yStep + zStep * zStep);
xStep = xStep / step;
yStep = yStep / step;
zStep = zStep / step;
// 當前爆炸強度，隨着距離和經過的方塊衰減
float strength = this.explosionSize * (0.7F + this.worldObj.rand.nextFloat() * 0.6F);
double blockX = this.explosionX;
double blockY = this.explosionY;
double blockZ = this.explosionZ;
for (; strength > 0.0F; strength -= 0.22500001F)
{
BlockPos blockPos = new BlockPos(blockX, blockY, blockZ);
IBlockState block = this.worldObj.getBlockState(blockPos);
// 爆炸強度衰減
if (block.getBlock().getMaterial() != Material.air)
{
float resistance = this.exploder != null ? this.exploder.getExplosionResistance(this, this.worldObj, blockPos, block) : block.getBlock().getExplosionResistance(worldObj, blockPos, (Entity)null, this);
strength -= (resistance + 0.3F) * 0.3F;
}
// 把這個方塊加入準備破壞的方塊
if (strength > 0.0F && (this.exploder == null || this.exploder.verifyExplosion(this, this.worldObj, blockPos, block, strength)))
{
blocksToDestroy.add(blockPos);
}
blockX += xStep * 0.30000001192092896D;
blockY += yStep * 0.30000001192092896D;
blockZ += zStep * 0.30000001192092896D;
}
}
}
}
}
// 把set轉爲array
this.affectedBlockPositions.addAll(blocksToDestroy);
// 接下來傷害實體
// 取包圍盒內的實體
float explosionSize = this.explosionSize * 2.0F;
int minX = MathHelper.floor_double(this.explosionX - (double)explosionSize - 1.0D);
int maxX = MathHelper.floor_double(this.explosionX + (double)explosionSize + 1.0D);
int minY = MathHelper.floor_double(this.explosionY - (double)explosionSize - 1.0D);
int maxY = MathHelper.floor_double(this.explosionY + (double)explosionSize + 1.0D);
int minZ = MathHelper.floor_double(this.explosionZ - (double)explosionSize - 1.0D);
int maxZ = MathHelper.floor_double(this.explosionZ + (double)explosionSize + 1.0D);
List<Entity> entityList = this.worldObj.getEntitiesWithinAABBExcludingEntity(this.exploder, new AxisAlignedBB((double)minX, (double)minY, (double)minZ, (double)maxX, (double)maxY, (double)maxZ));
net.minecraftforge.event.ForgeEventFactory.onExplosionDetonate(this.worldObj, this, entityList, explosionSize);
Vec3 vec3 = new Vec3(this.explosionX, this.explosionY, this.explosionZ);
for (int i = 0; i < entityList.size(); ++i)
{
Entity entity = (Entity)entityList.get(i);
// 實體不免疫爆炸
if (!entity.isImmuneToExplosions())
{
// 用來判斷是否在爆炸範圍內的距離
double _dist = entity.getDistance(this.explosionX, this.explosionY, this.explosionZ) / (double)explosionSize;
if (_dist <= 1.0D)
{
// 用來計算擊退方向的距離
double xDist = entity.posX - this.explosionX;
double yDist = entity.posY + (double)entity.getEyeHeight() - this.explosionY;
double zDist = entity.posZ - this.explosionZ;
double dist = (double)MathHelper.sqrt_double(xDist * xDist + yDist * yDist + zDist * zDist);
if (dist != 0.0D) // 這句基本沒用，只是防止除數爲0吧
{
// 歸一化
xDist = xDist / dist;
yDist = yDist / dist;
zDist = zDist / dist;
// 從爆炸中心到實體邊界上各點連線，中間沒有方塊擋住的比例，即實體受到爆炸影響的比例
double strengthScale = (double)this.worldObj.getBlockDensity(vec3, entity.getEntityBoundingBox());
double strength = (1.0D - _dist) * strengthScale;
// 傷害實體
entity.attackEntityFrom(DamageSource.setExplosionSource(this), (float)((int)((strength * strength + strength) / 2.0D * 8.0D * (double)explosionSize + 1.0D)));
// 擊退，附魔爆炸保護會減少擊退
double motionScale = EnchantmentProtection.func_92092_a(entity, strength);
entity.motionX += xDist * motionScale;
entity.motionY += yDist * motionScale;
entity.motionZ += zDist * motionScale;
// 記錄玩家擊退
if (entity instanceof EntityPlayer && !((EntityPlayer)entity).capabilities.disableDamage)
{
this.playerKnockbackMap.put((EntityPlayer)entity, new Vec3(xDist * strength, yDist * strength, zDist * strength));
}
}
}
}
}
}
/**
* Does the second part of the explosion (sound, particles, drop spawn)
*/
public void doExplosionB(boolean spawnParticles)
{
// 播放爆炸音效
this.worldObj.playSoundEffect(this.explosionX, this.explosionY, this.explosionZ, "random.explode", 4.0F, (1.0F + (this.worldObj.rand.nextFloat() - this.worldObj.rand.nextFloat()) * 0.2F) * 0.7F);
// 生成大爆炸粒子效果
if (this.explosionSize >= 2.0F && this.isSmoking)
{
this.worldObj.spawnParticle(EnumParticleTypes.EXPLOSION_HUGE, this.explosionX, this.explosionY, this.explosionZ, 1.0D, 0.0D, 0.0D, new int[0]);
}
else
{
this.worldObj.spawnParticle(EnumParticleTypes.EXPLOSION_LARGE, this.explosionX, this.explosionY, this.explosionZ, 1.0D, 0.0D, 0.0D, new int[0]);
}
// 破壞方塊
if (this.isSmoking)
{
// 遍歷被破壞的方塊
for (BlockPos blockpos : this.affectedBlockPositions)
{
Block block = this.worldObj.getBlockState(blockpos).getBlock();
// 生成爆炸和煙粒子效果
if (spawnParticles)
{
double x = (double)((float)blockpos.getX() + this.worldObj.rand.nextFloat());
double y = (double)((float)blockpos.getY() + this.worldObj.rand.nextFloat());
double z = (double)((float)blockpos.getZ() + this.worldObj.rand.nextFloat());
double xDist = x - this.explosionX;
double yDist = y - this.explosionY;
double zDist = z - this.explosionZ;
double dist = (double)MathHelper.sqrt_double(xDist * xDist + yDist * yDist + zDist * zDist);
// 歸一化
xDist = xDist / dist;
yDist = yDist / dist;
zDist = zDist / dist;
double distScale = 0.5D / (dist / (double)this.explosionSize + 0.1D);
distScale = distScale * (double)(this.worldObj.rand.nextFloat() * this.worldObj.rand.nextFloat() + 0.3F);
xDist = xDist * distScale;
yDist = yDist * distScale;
zDist = zDist * distScale;
this.worldObj.spawnParticle(EnumParticleTypes.EXPLOSION_NORMAL, (x + this.explosionX ) / 2.0D, (y + this.explosionY) / 2.0D, (z + this.explosionZ) / 2.0D, xDist, yDist, zDist, new int[0]);
this.worldObj.spawnParticle(EnumParticleTypes.SMOKE_NORMAL, x, y, z, xDist, yDist, zDist, new int[0]);
}
// 破壞方塊
if (block.getMaterial() != Material.air)
{
if (block.canDropFromExplosion(this))
{
block.dropBlockAsItemWithChance(this.worldObj, blockpos, this.worldObj.getBlockState(blockpos), 1.0F / this.explosionSize, 0);
}
block.onBlockExploded(this.worldObj, blockpos, this);
}
}
}
// 着火
if (this.isFlaming)
{
for (BlockPos blockpos1 : this.affectedBlockPositions)
{
if ( this.worldObj.getBlockState(blockpos1).getBlock().getMaterial() == Material.air
&& this.worldObj.getBlockState(blockpos1.down()).getBlock().isFullBlock()
&& this.explosionRNG.nextInt(3) == 0)
{
this.worldObj.setBlockState(blockpos1, Blocks.fire.getDefaultState());
}
}
}
}這個函數用來計算實體暴露給爆炸中心的比例，代表受到爆炸的影響
類名net.minecraft.world.World
/**
* Gets the percentage of real blocks within within a bounding box, along a specified vector.
*/
public float getBlockDensity(Vec3 vec, AxisAlignedBB bb)
{
double xStep = 1.0D / ((bb.maxX - bb.minX) * 2.0D + 1.0D);
double yStep = 1.0D / ((bb.maxY - bb.minY) * 2.0D + 1.0D);
double zStep = 1.0D / ((bb.maxZ - bb.minZ) * 2.0D + 1.0D);
double xOffset = (1.0D - Math.floor(1.0D / xStep) * xStep) / 2.0D;
double zOffset = (1.0D - Math.floor(1.0D / zStep) * zStep) / 2.0D;
if (xStep >= 0.0D && yStep >= 0.0D && zStep >= 0.0D)
{
int noBlockLines = 0;
int totalLines = 0;
// xt、yt、zt爲插值參數
for (float xt = 0.0F; xt <= 1.0F; xt = (float)((double)xt + xStep))
{
for (float yt = 0.0F; yt <= 1.0F; yt = (float)((double)yt + yStep))
{
for (float zt = 0.0F; zt <= 1.0F; zt = (float)((double)zt + zStep))
{
double x = bb.minX + (bb.maxX - bb.minX) * (double)xt;
double y = bb.minY + (bb.maxY - bb.minY) * (double)yt;
double z = bb.minZ + (bb.maxZ - bb.minZ) * (double)zt;
// 爆炸中心到包圍盒上這個點之間沒有方塊。rayTraceBlocks在我之前的博文逆向過了
if (this.rayTraceBlocks(new Vec3(x + xOffset, y, z + zOffset), vec) == null)
{
++noBlockLines;
}
++totalLines;
}
}
}
return (float)noBlockLines / (float)totalLines;
}
else
{
return 0.0F;
}
}