413 lines
8.8 KiB
C++
413 lines
8.8 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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cTracer::cTracer(cWorld * a_World)
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: m_World(a_World)
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{
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m_NormalTable[0].Set(-1, 0, 0);
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m_NormalTable[1].Set( 0, 0, -1);
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m_NormalTable[2].Set( 1, 0, 0);
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m_NormalTable[3].Set( 0, 0, 1);
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m_NormalTable[4].Set( 0, 1, 0);
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m_NormalTable[5].Set( 0, -1, 0);
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}
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cTracer::~cTracer()
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{
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}
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float cTracer::SigNum( float a_Num)
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{
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if (a_Num < 0.f) return -1.f;
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if (a_Num > 0.f) return 1.f;
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return 0.f;
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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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// calculate the direction of the ray (linear algebra)
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dir = a_Direction;
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// decide which direction to start walking in
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step.x = (int) SigNum(dir.x);
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step.y = (int) SigNum(dir.y);
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step.z = (int) SigNum(dir.z);
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// normalize the direction vector
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if (dir.SqrLength() > 0.f) 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 (dir.x != 0.f)
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{
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tDelta.x = 1 / fabs(dir.x);
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}
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else
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{
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tDelta.x = 0;
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}
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if (dir.y != 0.f)
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{
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tDelta.y = 1 / fabs(dir.y);
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}
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else
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{
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tDelta.y = 0;
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}
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if (dir.z != 0.f)
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{
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tDelta.z = 1 / fabs(dir.z);
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}
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else
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{
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tDelta.z = 0;
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}
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// start voxel coordinates
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pos.x = (int)floorf(a_Start.x);
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pos.y = (int)floorf(a_Start.y);
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pos.z = (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 (dir.x < 0)
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{
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tMax.x = ((float)pos.x - a_Start.x) / dir.x;
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}
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else
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{
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tMax.x = (((float)pos.x + 1) - a_Start.x) / dir.x;
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}
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if (dir.y < 0)
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{
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tMax.y = ((float)pos.y - a_Start.y) / dir.y;
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}
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else
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{
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tMax.y = (((float)pos.y + 1) - a_Start.y) / dir.y;
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}
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if (dir.z < 0)
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{
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tMax.z = ((float)pos.z - a_Start.z) / dir.z;
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}
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else
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{
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tMax.z = (((float)pos.z + 1) - a_Start.z) / dir.z;
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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_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 + (dir * (float)a_Distance);
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if (End.y < 0)
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{
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float dist = -a_Start.y / dir.y;
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End = a_Start + (dir * dist);
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}
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// end voxel coordinates
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end1.x = (int)floorf(End.x);
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end1.y = (int)floorf(End.y);
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end1.z = (int)floorf(End.z);
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// check if first is occupied
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if (pos.Equals(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 ((tMax.x < tMax.y) && (tMax.x < tMax.z))
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{
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tMax.x += tDelta.x;
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pos.x += step.x;
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}
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else if (tMax.y < tMax.z)
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{
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tMax.y += tDelta.y;
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pos.y += step.y;
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}
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else
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{
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tMax.z += tDelta.z;
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pos.z += step.z;
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}
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if (step.x > 0.0f)
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{
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if (pos.x >= 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 (pos.x <= end1.x)
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{
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reachedX = true;
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}
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if (step.y > 0.0f)
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{
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if (pos.y >= 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 (pos.y <= end1.y)
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{
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reachedY = true;
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}
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if (step.z > 0.0f)
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{
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if (pos.z >= 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 (pos.z <= 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 ((pos.y < 0) || (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(pos.x, pos.y, pos.z);
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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 = pos;
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int Normal = GetHitNormal(a_Start, End, pos);
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if (Normal > 0)
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{
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HitNormal = m_NormalTable[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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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 (abs(d)<0.001) {return 0;}
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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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const float EPSILON = 0.0001f;
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if (fabs(D) < EPSILON)
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{
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// segment is parallel to plane
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if (N == 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 & start, const Vector3f & end, const Vector3i & a_BlockPos)
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{
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Vector3i SmallBlockPos = a_BlockPos;
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char BlockID = 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 = (end - 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( start.x, start.y, end.x, 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( start.x, start.z, end.x, 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( start, 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( start.z, start.y, end.z, 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( start.z, start.x, end.z, 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( start, 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( start.x, start.y, end.x, 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( start.x, start.z, end.x, 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( start, 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( start.z, start.y, end.z, 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( start.z, start.x, end.z, 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( start, 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( start.y, start.x, end.y, 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( start.y, start.z, end.y, 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( start, 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( start.y, start.x, end.y, 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( start.y, start.z, end.y, 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( start, 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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