451 lines
10 KiB
C++
451 lines
10 KiB
C++
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#include "Globals.h" // NOTE: MSVC stupidness requires this to be the same across all modules
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#include "Tracer.h"
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#include "World.h"
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#include "Entities/Entity.h"
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#ifndef _WIN32
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#include <stdlib.h>
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#endif
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const float FLOAT_EPSILON = 0.0001f; // TODO: Stash this in some header where it can be reused
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const std::array<const Vector3f, 6>& cTracer::m_NormalTable(void)
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{
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static std::array<const Vector3f, 6>* table =
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new std::array<const Vector3f, 6>
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{
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{
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Vector3f(-1, 0, 0), // 1: -x
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Vector3f( 0, 0, -1), // 2: -z
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Vector3f( 1, 0, 0), // 3: +x
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Vector3f( 0, 0, 1), // 4: +z
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Vector3f( 0, 1, 0), // 5: +y
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Vector3f( 0, -1, 0) // 6: -y
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}
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};
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return *table;
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};
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cTracer::cTracer(cWorld * a_World):
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m_World(a_World)
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{
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}
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cTracer::~cTracer()
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{
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}
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int cTracer::SigNum(float a_Num)
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{
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if (a_Num < 0.f)
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{
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return -1;
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}
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if (a_Num > 0.f)
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{
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return 1;
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}
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return 0;
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}
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void cTracer::SetValues(const Vector3f & a_Start, const Vector3f & a_Direction)
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{
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// Since this method should only be called by Trace, zero length vectors should already have been taken care of
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ASSERT(a_Direction.HasNonZeroLength());
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// calculate the direction of the ray (linear algebra)
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m_Dir = a_Direction;
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// decide which direction to start walking in
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m_Step.x = SigNum(m_Dir.x);
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m_Step.y = SigNum(m_Dir.y);
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m_Step.z = SigNum(m_Dir.z);
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// normalize the direction vector
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m_Dir.Normalize();
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// how far we must move in the ray direction before
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// we encounter a new voxel in x-direction
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// same but y-direction
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if (m_Dir.x != 0.f)
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{
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m_tDelta.x = 1 / std::abs(m_Dir.x);
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}
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else
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{
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m_tDelta.x = 0;
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}
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if (m_Dir.y != 0.f)
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{
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m_tDelta.y = 1 / std::abs(m_Dir.y);
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}
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else
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{
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m_tDelta.y = 0;
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}
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if (m_Dir.z != 0.f)
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{
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m_tDelta.z = 1 / std::abs(m_Dir.z);
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}
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else
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{
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m_tDelta.z = 0;
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}
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// start voxel coordinates
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m_Pos.x = static_cast<int>(floorf(a_Start.x));
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m_Pos.y = static_cast<int>(floorf(a_Start.y));
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m_Pos.z = static_cast<int>(floorf(a_Start.z));
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// calculate distance to first intersection in the voxel we start from
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if (m_Dir.x < 0)
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{
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m_tMax.x = (static_cast<float>(m_Pos.x) - a_Start.x) / m_Dir.x;
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}
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else
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{
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m_tMax.x = (static_cast<float>(m_Pos.x + 1) - a_Start.x) / m_Dir.x; // TODO: Possible division by zero
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}
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if (m_Dir.y < 0)
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{
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m_tMax.y = (static_cast<float>(m_Pos.y) - a_Start.y) / m_Dir.y;
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}
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else
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{
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m_tMax.y = (static_cast<float>(m_Pos.y + 1) - a_Start.y) / m_Dir.y; // TODO: Possible division by zero
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}
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if (m_Dir.z < 0)
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{
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m_tMax.z = (static_cast<float>(m_Pos.z) - a_Start.z) / m_Dir.z;
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}
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else
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{
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m_tMax.z = (static_cast<float>(m_Pos.z + 1) - a_Start.z) / m_Dir.z; // TODO: Possible division by zero
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}
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}
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bool cTracer::Trace(const Vector3f & a_Start, const Vector3f & a_Direction, int a_Distance, bool a_LineOfSight)
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{
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if (!a_Direction.HasNonZeroLength())
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{
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return false;
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}
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if ((a_Start.y < 0) || (a_Start.y >= cChunkDef::Height))
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{
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LOGD("%s: Start Y is outside the world (%.2f), not tracing.", __FUNCTION__, a_Start.y);
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return false;
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}
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SetValues(a_Start, a_Direction);
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Vector3f End = a_Start + (m_Dir * static_cast<float>(a_Distance));
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if (End.y < 0)
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{
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float dist = -a_Start.y / m_Dir.y; // No division by 0 possible
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End = a_Start + (m_Dir * dist);
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}
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// end voxel coordinates
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m_End1.x = static_cast<int>(floorf(End.x));
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m_End1.y = static_cast<int>(floorf(End.y));
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m_End1.z = static_cast<int>(floorf(End.z));
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// check if first is occupied
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if (m_Pos.Equals(m_End1))
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{
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return false;
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}
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bool reachedX = false, reachedY = false, reachedZ = false;
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int Iterations = 0;
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while (Iterations < a_Distance)
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{
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Iterations++;
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if ((m_tMax.x < m_tMax.y) && (m_tMax.x < m_tMax.z))
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{
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m_tMax.x += m_tDelta.x;
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m_Pos.x += m_Step.x;
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}
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else if (m_tMax.y < m_tMax.z)
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{
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m_tMax.y += m_tDelta.y;
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m_Pos.y += m_Step.y;
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}
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else
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{
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m_tMax.z += m_tDelta.z;
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m_Pos.z += m_Step.z;
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}
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if (m_Step.x > 0.0f)
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{
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if (m_Pos.x >= m_End1.x)
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{
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reachedX = true;
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}
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}
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else if (m_Pos.x <= m_End1.x)
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{
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reachedX = true;
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}
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if (m_Step.y > 0.0f)
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{
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if (m_Pos.y >= m_End1.y)
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{
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reachedY = true;
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}
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}
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else if (m_Pos.y <= m_End1.y)
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{
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reachedY = true;
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}
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if (m_Step.z > 0.0f)
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{
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if (m_Pos.z >= m_End1.z)
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{
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reachedZ = true;
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}
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}
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else if (m_Pos.z <= m_End1.z)
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{
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reachedZ = true;
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}
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if (reachedX && reachedY && reachedZ)
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{
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return false;
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}
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if ((m_Pos.y < 0) || (m_Pos.y >= cChunkDef::Height))
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{
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return false;
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}
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BLOCKTYPE BlockID = m_World->GetBlock(m_Pos);
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// Block is counted as a collision if we are not doing a line of sight and it is solid,
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// or if the block is not air and not water. That way mobs can still see underwater.
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if ((!a_LineOfSight && cBlockInfo::IsSolid(BlockID)) || (a_LineOfSight && (BlockID != E_BLOCK_AIR) && !IsBlockWater(BlockID)))
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{
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BlockHitPosition = m_Pos;
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int Normal = GetHitNormal(a_Start, End, m_Pos);
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if (Normal > 0)
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{
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HitNormal = m_NormalTable()[static_cast<size_t>(Normal - 1)];
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}
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return true;
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}
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}
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return false;
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}
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// return 1 = hit, other is not hit
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static int LinesCross(float x0, float y0, float x1, float y1, float x2, float y2, float x3, float y3)
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{
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// float linx, liny;
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float d = (x1 - x0) * (y3 - y2) - (y1 - y0) * (x3 - x2);
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if (std::abs(d) < 0.001)
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{
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return 0;
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}
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float AB = ((y0 - y2) * (x3 - x2) - (x0 - x2) * (y3 - y2)) / d;
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if ((AB >= 0.0) && (AB <= 1.0))
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{
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float CD = ((y0 - y2) * (x1 - x0) - (x0 - x2) * (y1 - y0)) / d;
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if ((CD >= 0.0) && (CD <= 1.0))
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{
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// linx = x0 + AB * (x1 - x0);
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// liny = y0 + AB * (y1 - y0);
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return 1;
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}
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}
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return 0;
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}
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// intersect3D_SegmentPlane(): intersect a segment and a plane
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// Input: a_Ray = a segment, and a_Plane = a plane = {Point V0; Vector n;}
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// Output: *I0 = the intersect point (when it exists)
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// Return: 0 = disjoint (no intersection)
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// 1 = intersection in the unique point *I0
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// 2 = the segment lies in the plane
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int cTracer::intersect3D_SegmentPlane(const Vector3f & a_Origin, const Vector3f & a_End, const Vector3f & a_PlanePos, const Vector3f & a_PlaneNormal)
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{
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Vector3f u = a_End - a_Origin; // a_Ray.P1 - S.P0;
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Vector3f w = a_Origin - a_PlanePos; // S.P0 - Pn.V0;
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float D = a_PlaneNormal.Dot(u); // dot(Pn.n, u);
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float N = -(a_PlaneNormal.Dot(w)); // -dot(a_Plane.n, w);
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if (std::abs(D) < FLOAT_EPSILON)
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{
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// segment is parallel to plane
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if (N == 0.0)
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{
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// segment lies in plane
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return 2;
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}
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return 0; // no intersection
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}
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// they are not parallel
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// compute intersect param
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float sI = N / D;
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if ((sI < 0) || (sI > 1))
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{
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return 0; // no intersection
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}
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// Vector3f I (a_Ray->GetOrigin() + sI * u);// S.P0 + sI * u; // compute segment intersect point
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RealHit = a_Origin + u * sI;
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return 1;
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}
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int cTracer::GetHitNormal(const Vector3f & a_Start, const Vector3f & a_End, const Vector3i & a_BlockPos)
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{
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Vector3i SmallBlockPos = a_BlockPos;
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BLOCKTYPE BlockID = static_cast<BLOCKTYPE>(m_World->GetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z));
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if ((BlockID == E_BLOCK_AIR) || IsBlockWater(BlockID))
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{
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return 0;
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}
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Vector3f BlockPos;
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BlockPos = Vector3f(SmallBlockPos);
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Vector3f Look = (a_End - a_Start);
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Look.Normalize();
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float dot = Look.Dot(Vector3f(-1, 0, 0)); // first face normal is x -1
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if (dot < 0)
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{
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int Lines = LinesCross(a_Start.x, a_Start.y, a_End.x, a_End.y, BlockPos.x, BlockPos.y, BlockPos.x, BlockPos.y + 1);
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if (Lines == 1)
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{
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Lines = LinesCross(a_Start.x, a_Start.z, a_End.x, a_End.z, BlockPos.x, BlockPos.z, BlockPos.x, BlockPos.z + 1);
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if (Lines == 1)
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{
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intersect3D_SegmentPlane(a_Start, a_End, BlockPos, Vector3f(-1, 0, 0));
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return 1;
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}
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}
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}
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dot = Look.Dot(Vector3f(0, 0, -1)); // second face normal is z -1
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if (dot < 0)
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{
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int Lines = LinesCross(a_Start.z, a_Start.y, a_End.z, a_End.y, BlockPos.z, BlockPos.y, BlockPos.z, BlockPos.y + 1);
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if (Lines == 1)
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{
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Lines = LinesCross(a_Start.z, a_Start.x, a_End.z, a_End.x, BlockPos.z, BlockPos.x, BlockPos.z, BlockPos.x + 1);
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if (Lines == 1)
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{
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intersect3D_SegmentPlane(a_Start, a_End, BlockPos, Vector3f(0, 0, -1));
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return 2;
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}
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}
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}
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dot = Look.Dot(Vector3f(1, 0, 0)); // third face normal is x 1
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if (dot < 0)
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{
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int Lines = LinesCross(a_Start.x, a_Start.y, a_End.x, a_End.y, BlockPos.x + 1, BlockPos.y, BlockPos.x + 1, BlockPos.y + 1);
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if (Lines == 1)
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{
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Lines = LinesCross(a_Start.x, a_Start.z, a_End.x, a_End.z, BlockPos.x + 1, BlockPos.z, BlockPos.x + 1, BlockPos.z + 1);
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if (Lines == 1)
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{
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intersect3D_SegmentPlane(a_Start, a_End, BlockPos + Vector3f(1, 0, 0), Vector3f(1, 0, 0));
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return 3;
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}
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}
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}
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dot = Look.Dot(Vector3f(0, 0, 1)); // fourth face normal is z 1
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if (dot < 0)
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{
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int Lines = LinesCross(a_Start.z, a_Start.y, a_End.z, a_End.y, BlockPos.z + 1, BlockPos.y, BlockPos.z + 1, BlockPos.y + 1);
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if (Lines == 1)
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{
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Lines = LinesCross(a_Start.z, a_Start.x, a_End.z, a_End.x, BlockPos.z + 1, BlockPos.x, BlockPos.z + 1, BlockPos.x + 1);
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if (Lines == 1)
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{
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intersect3D_SegmentPlane(a_Start, a_End, BlockPos + Vector3f(0, 0, 1), Vector3f(0, 0, 1));
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return 4;
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}
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}
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}
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dot = Look.Dot(Vector3f(0, 1, 0)); // fifth face normal is y 1
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if (dot < 0)
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{
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int Lines = LinesCross(a_Start.y, a_Start.x, a_End.y, a_End.x, BlockPos.y + 1, BlockPos.x, BlockPos.y + 1, BlockPos.x + 1);
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if (Lines == 1)
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{
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Lines = LinesCross(a_Start.y, a_Start.z, a_End.y, a_End.z, BlockPos.y + 1, BlockPos.z, BlockPos.y + 1, BlockPos.z + 1);
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if (Lines == 1)
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{
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intersect3D_SegmentPlane(a_Start, a_End, BlockPos + Vector3f(0, 1, 0), Vector3f(0, 1, 0));
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return 5;
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}
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}
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}
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dot = Look.Dot(Vector3f(0, -1, 0)); // sixth face normal is y -1
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if (dot < 0)
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{
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int Lines = LinesCross(a_Start.y, a_Start.x, a_End.y, a_End.x, BlockPos.y, BlockPos.x, BlockPos.y, BlockPos.x + 1);
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if (Lines == 1)
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{
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Lines = LinesCross(a_Start.y, a_Start.z, a_End.y, a_End.z, BlockPos.y, BlockPos.z, BlockPos.y, BlockPos.z + 1);
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if (Lines == 1)
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{
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intersect3D_SegmentPlane(a_Start, a_End, BlockPos, Vector3f(0, -1, 0));
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return 6;
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}
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}
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}
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return 0;
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}
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