296 lines
11 KiB
C++
296 lines
11 KiB
C++
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#include "Globals.h"
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#include "BlockInfo.h"
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#include "Blocks/BlockHandler.h"
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#include "Blocks/ChunkInterface.h"
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#include "Chunk.h"
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#include "ClientHandle.h"
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#include "Entities/FallingBlock.h"
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#include "LineBlockTracer.h"
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#include "Simulator/SandSimulator.h"
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namespace Explodinator
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{
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const auto StepUnit = 0.3f;
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const auto KnockbackFactor = 25U;
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const auto StepAttenuation = 0.225f;
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const auto TraceCubeSideLength = 16U;
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const auto BoundingBoxStepUnit = 0.5f;
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/** Converts an absolute floating-point Position into a Chunk-relative one. */
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static Vector3f AbsoluteToRelative(const Vector3f a_Position, const cChunkCoords a_ChunkPosition)
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{
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return { a_Position.x - a_ChunkPosition.m_ChunkX * cChunkDef::Width, a_Position.y, a_Position.z - a_ChunkPosition.m_ChunkZ * cChunkDef::Width };
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}
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/** Make a From Chunk-relative Position into a To Chunk-relative position. */
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static Vector3f RebaseRelativePosition(const cChunkCoords a_From, const cChunkCoords a_To, const Vector3f a_Position)
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{
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return
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{
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a_Position.x + (a_From.m_ChunkX - a_To.m_ChunkX) * cChunkDef::Width,
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a_Position.y,
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a_Position.z + (a_From.m_ChunkZ - a_To.m_ChunkZ) * cChunkDef::Width
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};
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}
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/** Calculates the approximate percentage of an Entity's bounding box that is exposed to an explosion centred at Position. */
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static float CalculateEntityExposure(cChunk & a_Chunk, const cEntity & a_Entity, const Vector3f a_Position, const float a_SquareRadius)
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{
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unsigned Unobstructed = 0, Total = 0;
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const auto Box = a_Entity.GetBoundingBox();
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for (float X = Box.GetMinX(); X < Box.GetMaxX(); X += BoundingBoxStepUnit)
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{
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for (float Y = Box.GetMinY(); Y < Box.GetMaxY(); Y += BoundingBoxStepUnit)
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{
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for (float Z = Box.GetMinZ(); Z < Box.GetMaxZ(); Z += BoundingBoxStepUnit)
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{
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const auto Destination = Vector3f(X, Y, Z);
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if ((Destination - a_Position).SqrLength() > a_SquareRadius)
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{
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// Don't bother with points outside our designated area-of-effect
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// This is, surprisingly, a massive amount of work saved (~3m to detonate a sphere of 37k TNT before, ~1m after):
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continue;
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}
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if (cLineBlockTracer::LineOfSightTrace(*a_Chunk.GetWorld(), a_Position, Destination, cLineBlockTracer::eLineOfSight::losAir))
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{
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Unobstructed++;
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}
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Total++;
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}
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}
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}
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return static_cast<float>(Unobstructed) / Total;
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}
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/** Applies distance-based damage and knockback to all entities within the explosion's effect range. */
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static void DamageEntities(cChunk & a_Chunk, const Vector3f a_Position, const unsigned a_Power)
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{
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const auto Radius = a_Power * 2.f;
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const auto SquareRadius = Radius * Radius;
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a_Chunk.GetWorld()->ForEachEntityInBox({ a_Position, Radius * 2 }, [&a_Chunk, a_Position, a_Power, Radius, SquareRadius](cEntity & Entity)
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{
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// Percentage of rays unobstructed.
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const auto Exposure = CalculateEntityExposure(a_Chunk, Entity, a_Position, SquareRadius);
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const auto Direction = Entity.GetPosition() - a_Position;
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const auto Impact = (1 - (static_cast<float>(Direction.Length()) / Radius)) * Exposure;
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// Don't apply damage to other TNT entities and falling blocks, they should be invincible:
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if (!Entity.IsTNT() && !Entity.IsFallingBlock())
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{
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const auto Damage = (Impact * Impact + Impact) * 7 * a_Power + 1;
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Entity.TakeDamage(dtExplosion, nullptr, FloorC(Damage), 0);
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}
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// Impact reduced by armour:
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const auto ReducedImpact = Impact - Impact * Entity.GetEnchantmentBlastKnockbackReduction(); // TODO: call is very expensive, should only apply to Pawns
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Entity.SetSpeed(Direction.NormalizeCopy() * KnockbackFactor * ReducedImpact);
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// Continue iteration:
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return false;
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});
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}
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/** Sets the block at the given position, updating surroundings. */
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static void DestroyBlock(cWorld & a_World, cChunk & a_Chunk, const Vector3i a_AbsolutePosition, const Vector3i a_RelativePosition, const BLOCKTYPE a_DestroyedBlock, const BLOCKTYPE a_NewBlock)
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{
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const auto DestroyedMeta = a_Chunk.GetMeta(a_RelativePosition);
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// SetBlock wakes up all simulators for the area, so that water and lava flows and sand falls into the blasted holes
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// It also is responsible for calling cBlockHandler::OnNeighborChanged to pop off blocks that fail CanBeAt
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// An explicit call to cBlockHandler::OnBroken handles the destruction of multiblock structures
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// References at (FS #391, GH #4418):
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a_Chunk.SetBlock(a_RelativePosition, a_NewBlock, 0);
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cChunkInterface Interface(a_World.GetChunkMap());
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cBlockInfo::GetHandler(a_DestroyedBlock)->OnBroken(Interface, a_World, a_AbsolutePosition, a_DestroyedBlock, DestroyedMeta);
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}
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/** Sets the block at the given Position to air, updates surroundings, and spawns pickups, fire, shrapnel according to Minecraft rules.
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OK, _mostly_ Minecraft rules. */
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static void DestroyBlock(cChunk & a_Chunk, const Vector3i a_Position, const unsigned a_Power, const bool a_Fiery)
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{
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const auto DestroyedBlock = a_Chunk.GetBlock(a_Position);
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if (DestroyedBlock == E_BLOCK_AIR)
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{
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// There's nothing left for us here, but a barren and empty land
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// Let's go.
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return;
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}
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auto & World = *a_Chunk.GetWorld();
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auto & Random = GetRandomProvider();
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const auto Absolute = cChunkDef::RelativeToAbsolute(a_Position, a_Chunk.GetPos());
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if (DestroyedBlock == E_BLOCK_TNT)
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{
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// Random fuse between 10 to 30 game ticks.
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const int FuseTime = Random.RandInt(10, 30);
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// Activate the TNT, with initial velocity and no fuse sound:
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World.SpawnPrimedTNT(Vector3d(0.5, 0, 0.5) + Absolute, FuseTime, 1, false);
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}
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else if (Random.RandBool(1.f / a_Power))
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{
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const auto DestroyedMeta = a_Chunk.GetMeta(a_Position);
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a_Chunk.GetWorld()->SpawnItemPickups(
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cBlockInfo::GetHandler(DestroyedBlock)->ConvertToPickups(DestroyedMeta, a_Chunk.GetBlockEntityRel(a_Position)),
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Absolute
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);
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}
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else if (a_Fiery && Random.RandBool(1.f / 3.f)) // 33% chance of starting fires if it can start fires
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{
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const auto Below = a_Position.addedY(-1);
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if ((Below.y >= 0) && cBlockInfo::FullyOccupiesVoxel(a_Chunk.GetBlock(Below)))
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{
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// Start a fire:
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DestroyBlock(World, a_Chunk, Absolute, a_Position, DestroyedBlock, E_BLOCK_FIRE);
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return;
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}
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}
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else if (const auto Shrapnel = World.GetTNTShrapnelLevel(); (Shrapnel > slNone) && Random.RandBool(0)) // 20% chance of flinging stuff around
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{
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// If the block is shrapnel-able, make a falling block entity out of it:
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if (
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((Shrapnel == slAll) && cBlockInfo::FullyOccupiesVoxel(DestroyedBlock)) ||
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((Shrapnel == slGravityAffectedOnly) && cSandSimulator::IsAllowedBlock(DestroyedBlock))
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)
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{
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const auto DestroyedMeta = a_Chunk.GetMeta(a_Position);
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auto FallingBlock = std::make_unique<cFallingBlock>(Vector3d(0.5, 0, 0.5) + Absolute, DestroyedBlock, DestroyedMeta);
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// TODO: correct velocity FallingBlock->SetSpeedY(40);
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FallingBlock->Initialize(std::move(FallingBlock), World);
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}
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}
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DestroyBlock(World, a_Chunk, Absolute, a_Position, DestroyedBlock, E_BLOCK_AIR);
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}
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/** Traces the path taken by one Explosion Lazor (tm) with given direction and intensity, that will destroy blocks until it is exhausted. */
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static void DestructionTrace(cChunk * a_Chunk, Vector3f a_Origin, const Vector3f a_Destination, const unsigned a_Power, const bool a_Fiery, float a_Intensity)
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{
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// The current position the ray is at.
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auto Checkpoint = a_Origin;
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// The total displacement the ray must travel.
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const auto TraceDisplacement = (a_Destination - a_Origin);
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// The displacement that they ray in one iteration step should travel.
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const auto Step = TraceDisplacement.NormalizeCopy() * StepUnit;
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// Loop until we've reached the prescribed destination:
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while (TraceDisplacement > (Checkpoint - a_Origin))
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{
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auto Position = Checkpoint.Floor();
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if (!cChunkDef::IsValidHeight(Position.y))
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{
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break;
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}
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const auto Neighbour = a_Chunk->GetRelNeighborChunkAdjustCoords(Position);
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if ((Neighbour == nullptr) || !Neighbour->IsValid())
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{
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break;
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}
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a_Intensity -= 0.3f * (0.3f + cBlockInfo::GetExplosionAbsorption(Neighbour->GetBlock(Position)));
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if (a_Intensity <= 0)
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{
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// The ray is exhausted:
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break;
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}
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DestroyBlock(*Neighbour, Position, a_Power, a_Fiery);
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// Adjust coordinates to be relative to the neighbour chunk:
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Checkpoint = RebaseRelativePosition(a_Chunk->GetPos(), Neighbour->GetPos(), Checkpoint);
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a_Origin = RebaseRelativePosition(a_Chunk->GetPos(), Neighbour->GetPos(), a_Origin);
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a_Chunk = Neighbour;
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// Increment the simulation, weaken the ray:
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Checkpoint += Step;
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a_Intensity -= StepAttenuation;
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}
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}
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/** Sends out Explosion Lazors (tm) originating from the given position that destroy blocks. */
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static void DamageBlocks(cChunk & a_Chunk, const Vector3f a_Position, const unsigned a_Power, const bool a_Fiery)
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{
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const auto Intensity = a_Power * (0.7f + GetRandomProvider().RandReal(0.6f));
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const auto ExplosionRadius = CeilC((Intensity / StepAttenuation) * StepUnit);
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// Oh boy... Better hope you have a hot cache, 'cos this little manoeuvre's gonna cost us 1352 raytraces in one tick...
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const int HalfSide = TraceCubeSideLength / 2;
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// The following loops implement the tracing algorithm described in http://minecraft.gamepedia.com/Explosion
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// Trace rays from the explosion centre to all points in a square of area TraceCubeSideLength * TraceCubeSideLength
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// in the YM and YP directions:
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for (int OffsetX = -HalfSide; OffsetX < HalfSide; OffsetX++)
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{
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for (int OffsetZ = -HalfSide; OffsetZ < HalfSide; OffsetZ++)
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{
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DestructionTrace(&a_Chunk, a_Position, a_Position + Vector3f(OffsetX, +ExplosionRadius, OffsetZ), a_Power, a_Fiery, Intensity);
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DestructionTrace(&a_Chunk, a_Position, a_Position + Vector3f(OffsetX, -ExplosionRadius, OffsetZ), a_Power, a_Fiery, Intensity);
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}
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}
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/*
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Trace rays from the centre to the sides of the explosion cube, being careful to avoid duplicates:
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Top view:
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______
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. | (dot to make style checker happy)
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| ______
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Side view:
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+ +
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|====== |
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| | |
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|====== |
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+ +
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*/
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for (int Offset = -HalfSide; Offset < HalfSide - 1; Offset++)
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{
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for (int OffsetY = -HalfSide + 1; OffsetY < HalfSide - 1; OffsetY++)
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{
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DestructionTrace(&a_Chunk, a_Position, a_Position + Vector3f(ExplosionRadius, OffsetY, Offset + 1), a_Power, a_Fiery, Intensity);
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DestructionTrace(&a_Chunk, a_Position, a_Position + Vector3f(-ExplosionRadius, OffsetY, Offset), a_Power, a_Fiery, Intensity);
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DestructionTrace(&a_Chunk, a_Position, a_Position + Vector3f(Offset, OffsetY, ExplosionRadius), a_Power, a_Fiery, Intensity);
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DestructionTrace(&a_Chunk, a_Position, a_Position + Vector3f(Offset + 1, OffsetY, -ExplosionRadius), a_Power, a_Fiery, Intensity);
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}
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}
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}
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/** Sends an explosion packet to all clients in the given chunk. */
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static void LagTheClient(cChunk & a_Chunk, const Vector3f a_Position, const unsigned a_Power)
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{
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for (const auto Client : a_Chunk.GetAllClients())
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{
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Client->SendExplosion(a_Position, a_Power);
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}
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}
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void Kaboom(cWorld & a_World, const Vector3f a_Position, const unsigned a_Power, const bool a_Fiery)
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{
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a_World.DoWithChunkAt(a_Position.Floor(), [a_Position, a_Power, a_Fiery](cChunk & a_Chunk)
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{
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LagTheClient(a_Chunk, a_Position, a_Power);
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DamageEntities(a_Chunk, a_Position, a_Power);
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DamageBlocks(a_Chunk, AbsoluteToRelative(a_Position, a_Chunk.GetPos()), a_Power, a_Fiery);
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return false;
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});
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}
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}
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