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cuberite-2a/src/Tracer.cpp

451 lines
9.7 KiB
C++

#include "Globals.h" // NOTE: MSVC stupidness requires this to be the same across all modules
#include "Tracer.h"
#include "World.h"
#include "Entities/Entity.h"
#ifndef _WIN32
#include <stdlib.h>
#endif
const float FLOAT_EPSILON = 0.0001f; // TODO: Stash this in some header where it can be reused
const std::array<const Vector3f, 6>& cTracer::m_NormalTable(void)
{
static std::array<const Vector3f, 6>* table =
new std::array<const Vector3f, 6>
{
{
Vector3f(-1, 0, 0), // 1: -x
Vector3f( 0, 0, -1), // 2: -z
Vector3f( 1, 0, 0), // 3: +x
Vector3f( 0, 0, 1), // 4: +z
Vector3f( 0, 1, 0), // 5: +y
Vector3f( 0, -1, 0) // 6: -y
}
};
return *table;
};
cTracer::cTracer(cWorld * a_World):
m_World(a_World)
{
}
cTracer::~cTracer()
{
}
int cTracer::SigNum(float a_Num)
{
if (a_Num < 0.f)
{
return -1;
}
if (a_Num > 0.f)
{
return 1;
}
return 0;
}
void cTracer::SetValues(const Vector3f & a_Start, const Vector3f & a_Direction)
{
// Since this method should only be called by Trace, zero length vectors should already have been taken care of
ASSERT(a_Direction.HasNonZeroLength());
// calculate the direction of the ray (linear algebra)
dir = a_Direction;
// decide which direction to start walking in
step.x = SigNum(dir.x);
step.y = SigNum(dir.y);
step.z = SigNum(dir.z);
// normalize the direction vector
dir.Normalize();
// how far we must move in the ray direction before
// we encounter a new voxel in x-direction
// same but y-direction
if (dir.x != 0.f)
{
tDelta.x = 1 / std::abs(dir.x);
}
else
{
tDelta.x = 0;
}
if (dir.y != 0.f)
{
tDelta.y = 1 / std::abs(dir.y);
}
else
{
tDelta.y = 0;
}
if (dir.z != 0.f)
{
tDelta.z = 1 / std::abs(dir.z);
}
else
{
tDelta.z = 0;
}
// start voxel coordinates
pos.x = static_cast<int>(floorf(a_Start.x));
pos.y = static_cast<int>(floorf(a_Start.y));
pos.z = static_cast<int>(floorf(a_Start.z));
// calculate distance to first intersection in the voxel we start from
if (dir.x < 0)
{
tMax.x = (static_cast<float>(pos.x) - a_Start.x) / dir.x;
}
else
{
tMax.x = (static_cast<float>(pos.x + 1) - a_Start.x) / dir.x; // TODO: Possible division by zero
}
if (dir.y < 0)
{
tMax.y = (static_cast<float>(pos.y) - a_Start.y) / dir.y;
}
else
{
tMax.y = (static_cast<float>(pos.y + 1) - a_Start.y) / dir.y; // TODO: Possible division by zero
}
if (dir.z < 0)
{
tMax.z = (static_cast<float>(pos.z) - a_Start.z) / dir.z;
}
else
{
tMax.z = (static_cast<float>(pos.z + 1) - a_Start.z) / dir.z; // TODO: Possible division by zero
}
}
bool cTracer::Trace(const Vector3f & a_Start, const Vector3f & a_Direction, int a_Distance, bool a_LineOfSight)
{
if (!a_Direction.HasNonZeroLength())
{
return false;
}
if ((a_Start.y < 0) || (a_Start.y >= cChunkDef::Height))
{
LOGD("%s: Start Y is outside the world (%.2f), not tracing.", __FUNCTION__, a_Start.y);
return false;
}
SetValues(a_Start, a_Direction);
Vector3f End = a_Start + (dir * static_cast<float>(a_Distance));
if (End.y < 0)
{
float dist = -a_Start.y / dir.y; // No division by 0 possible
End = a_Start + (dir * dist);
}
// end voxel coordinates
end1.x = static_cast<int>(floorf(End.x));
end1.y = static_cast<int>(floorf(End.y));
end1.z = static_cast<int>(floorf(End.z));
// check if first is occupied
if (pos.Equals(end1))
{
return false;
}
bool reachedX = false, reachedY = false, reachedZ = false;
int Iterations = 0;
while (Iterations < a_Distance)
{
Iterations++;
if ((tMax.x < tMax.y) && (tMax.x < tMax.z))
{
tMax.x += tDelta.x;
pos.x += step.x;
}
else if (tMax.y < tMax.z)
{
tMax.y += tDelta.y;
pos.y += step.y;
}
else
{
tMax.z += tDelta.z;
pos.z += step.z;
}
if (step.x > 0.0f)
{
if (pos.x >= end1.x)
{
reachedX = true;
}
}
else if (pos.x <= end1.x)
{
reachedX = true;
}
if (step.y > 0.0f)
{
if (pos.y >= end1.y)
{
reachedY = true;
}
}
else if (pos.y <= end1.y)
{
reachedY = true;
}
if (step.z > 0.0f)
{
if (pos.z >= end1.z)
{
reachedZ = true;
}
}
else if (pos.z <= end1.z)
{
reachedZ = true;
}
if (reachedX && reachedY && reachedZ)
{
return false;
}
if ((pos.y < 0) || (pos.y >= cChunkDef::Height))
{
return false;
}
BLOCKTYPE BlockID = m_World->GetBlock(pos.x, pos.y, pos.z);
// Block is counted as a collision if we are not doing a line of sight and it is solid,
// or if the block is not air and not water. That way mobs can still see underwater.
if ((!a_LineOfSight && cBlockInfo::IsSolid(BlockID)) || (a_LineOfSight && (BlockID != E_BLOCK_AIR) && !IsBlockWater(BlockID)))
{
BlockHitPosition = pos;
int Normal = GetHitNormal(a_Start, End, pos);
if (Normal > 0)
{
HitNormal = m_NormalTable()[Normal - 1];
}
return true;
}
}
return false;
}
// return 1 = hit, other is not hit
static int LinesCross(float x0, float y0, float x1, float y1, float x2, float y2, float x3, float y3)
{
// float linx, liny;
float d = (x1 - x0) * (y3 - y2) - (y1 - y0) * (x3 - x2);
if (std::abs(d) < 0.001)
{
return 0;
}
float AB = ((y0 - y2) * (x3 - x2) - (x0 - x2) * (y3 - y2)) / d;
if ((AB >= 0.0) && (AB <= 1.0))
{
float CD = ((y0 - y2) * (x1 - x0) - (x0 - x2) * (y1 - y0)) / d;
if ((CD >= 0.0) && (CD <= 1.0))
{
// linx = x0 + AB * (x1 - x0);
// liny = y0 + AB * (y1 - y0);
return 1;
}
}
return 0;
}
// intersect3D_SegmentPlane(): intersect a segment and a plane
// Input: a_Ray = a segment, and a_Plane = a plane = {Point V0; Vector n;}
// Output: *I0 = the intersect point (when it exists)
// Return: 0 = disjoint (no intersection)
// 1 = intersection in the unique point *I0
// 2 = the segment lies in the plane
int cTracer::intersect3D_SegmentPlane(const Vector3f & a_Origin, const Vector3f & a_End, const Vector3f & a_PlanePos, const Vector3f & a_PlaneNormal)
{
Vector3f u = a_End - a_Origin; // a_Ray.P1 - S.P0;
Vector3f w = a_Origin - a_PlanePos; // S.P0 - Pn.V0;
float D = a_PlaneNormal.Dot(u); // dot(Pn.n, u);
float N = -(a_PlaneNormal.Dot(w)); // -dot(a_Plane.n, w);
if (std::abs(D) < FLOAT_EPSILON)
{
// segment is parallel to plane
if (N == 0.0)
{
// segment lies in plane
return 2;
}
return 0; // no intersection
}
// they are not parallel
// compute intersect param
float sI = N / D;
if ((sI < 0) || (sI > 1))
{
return 0; // no intersection
}
// Vector3f I (a_Ray->GetOrigin() + sI * u);// S.P0 + sI * u; // compute segment intersect point
RealHit = a_Origin + u * sI;
return 1;
}
int cTracer::GetHitNormal(const Vector3f & start, const Vector3f & end, const Vector3i & a_BlockPos)
{
Vector3i SmallBlockPos = a_BlockPos;
char BlockID = m_World->GetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z);
if ((BlockID == E_BLOCK_AIR) || IsBlockWater(BlockID))
{
return 0;
}
Vector3f BlockPos;
BlockPos = Vector3f(SmallBlockPos);
Vector3f Look = (end - start);
Look.Normalize();
float dot = Look.Dot(Vector3f(-1, 0, 0)); // first face normal is x -1
if (dot < 0)
{
int Lines = LinesCross(start.x, start.y, end.x, end.y, BlockPos.x, BlockPos.y, BlockPos.x, BlockPos.y + 1);
if (Lines == 1)
{
Lines = LinesCross(start.x, start.z, end.x, end.z, BlockPos.x, BlockPos.z, BlockPos.x, BlockPos.z + 1);
if (Lines == 1)
{
intersect3D_SegmentPlane(start, end, BlockPos, Vector3f(-1, 0, 0));
return 1;
}
}
}
dot = Look.Dot(Vector3f(0, 0, -1)); // second face normal is z -1
if (dot < 0)
{
int Lines = LinesCross(start.z, start.y, end.z, end.y, BlockPos.z, BlockPos.y, BlockPos.z, BlockPos.y + 1);
if (Lines == 1)
{
Lines = LinesCross(start.z, start.x, end.z, end.x, BlockPos.z, BlockPos.x, BlockPos.z, BlockPos.x + 1);
if (Lines == 1)
{
intersect3D_SegmentPlane(start, end, BlockPos, Vector3f(0, 0, -1));
return 2;
}
}
}
dot = Look.Dot(Vector3f(1, 0, 0)); // third face normal is x 1
if (dot < 0)
{
int Lines = LinesCross(start.x, start.y, end.x, end.y, BlockPos.x + 1, BlockPos.y, BlockPos.x + 1, BlockPos.y + 1);
if (Lines == 1)
{
Lines = LinesCross(start.x, start.z, end.x, end.z, BlockPos.x + 1, BlockPos.z, BlockPos.x + 1, BlockPos.z + 1);
if (Lines == 1)
{
intersect3D_SegmentPlane(start, end, BlockPos + Vector3f(1, 0, 0), Vector3f(1, 0, 0));
return 3;
}
}
}
dot = Look.Dot(Vector3f(0, 0, 1)); // fourth face normal is z 1
if (dot < 0)
{
int Lines = LinesCross(start.z, start.y, end.z, end.y, BlockPos.z + 1, BlockPos.y, BlockPos.z + 1, BlockPos.y + 1);
if (Lines == 1)
{
Lines = LinesCross(start.z, start.x, end.z, end.x, BlockPos.z + 1, BlockPos.x, BlockPos.z + 1, BlockPos.x + 1);
if (Lines == 1)
{
intersect3D_SegmentPlane(start, end, BlockPos + Vector3f(0, 0, 1), Vector3f(0, 0, 1));
return 4;
}
}
}
dot = Look.Dot(Vector3f(0, 1, 0)); // fifth face normal is y 1
if (dot < 0)
{
int Lines = LinesCross(start.y, start.x, end.y, end.x, BlockPos.y + 1, BlockPos.x, BlockPos.y + 1, BlockPos.x + 1);
if (Lines == 1)
{
Lines = LinesCross(start.y, start.z, end.y, end.z, BlockPos.y + 1, BlockPos.z, BlockPos.y + 1, BlockPos.z + 1);
if (Lines == 1)
{
intersect3D_SegmentPlane(start, end, BlockPos + Vector3f(0, 1, 0), Vector3f(0, 1, 0));
return 5;
}
}
}
dot = Look.Dot(Vector3f(0, -1, 0)); // sixth face normal is y -1
if (dot < 0)
{
int Lines = LinesCross(start.y, start.x, end.y, end.x, BlockPos.y, BlockPos.x, BlockPos.y, BlockPos.x + 1);
if (Lines == 1)
{
Lines = LinesCross(start.y, start.z, end.y, end.z, BlockPos.y, BlockPos.z, BlockPos.y, BlockPos.z + 1);
if (Lines == 1)
{
intersect3D_SegmentPlane(start, end, BlockPos, Vector3f(0, -1, 0));
return 6;
}
}
}
return 0;
}