/* EQ2Emulator: Everquest II Server Emulator Copyright (C) 2007 EQ2EMulator Development Team (http://www.eq2emulator.net) This file is part of EQ2Emulator. EQ2Emulator is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. EQ2Emulator is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with EQ2Emulator. If not, see . */ #include "SPGrid.h" #include "../../common/Log.h" SPGrid::SPGrid(string file, int32 cellSize) { m_ZoneFile = file; m_CellSize = cellSize; m_MinX = 0; m_MinZ = 0; m_MaxX = 0; m_MaxZ = 0; m_NumCellsX = 0; m_NumCellsZ = 0; m_NumFaceCellsX = 0; m_NumFaceCellsZ = 0; } SPGrid::~SPGrid() { vector::iterator CellItr; map >::iterator MapItr; vector::iterator FaceItr; map deadPtrs; // Loop through the vector of cells for (CellItr = m_FaceCells.begin(); CellItr != m_FaceCells.end(); CellItr++) { // Loop through the map of vertices on this cell for (MapItr = (*CellItr).FaceList.begin(); MapItr != (*CellItr).FaceList.end(); MapItr++) { // Loop through the vector of faces in the map and delete the pointers for (FaceItr = (*MapItr).second.begin(); FaceItr != (*MapItr).second.end(); FaceItr++) { if(deadPtrs.count((*FaceItr)) == 0) { deadPtrs.insert(make_pair((*FaceItr), true)); safe_delete((*FaceItr)); } } } } } bool SPGrid::Init() { // Make sure we have a zone file if (m_ZoneFile.empty()) { LogWrite(ZONE__ERROR, 0, "SPGrid", "SPGrid::Init() m_ZoneFile is empty."); return false; } // Make sure we have a cell size if (m_CellSize == 0) m_CellSize = CELLSIZEDEFAULT; // Open the map file for this zone string filePath = "Maps/" + m_ZoneFile + ".EQ2Map"; FILE* file = fopen(filePath.c_str(), "rb"); if (file == nullptr) { LogWrite(ZONE__WARNING, 0, "SPGrid", "SPGrid::Init() unable to open the map file for %s. (zoneserver will continue to run fine without it)", m_ZoneFile.c_str()); return false; } // Read the string for the zone file name this was created for int8 strSize; char name[256]; fread(&strSize, sizeof(int8), 1, file); LogWrite(ZONE__DEBUG, 0, "SPGrid", "strSize = %u", strSize); size_t len = fread(&name, sizeof(char), strSize, file); name[len] = '\0'; LogWrite(ZONE__DEBUG, 0, "SPGrid", "name = %s", name); string fileName(name); std::size_t found = fileName.find(m_ZoneFile); // Make sure file contents are for the correct zone if (found == std::string::npos) { fclose(file); LogWrite(ZONE__ERROR, 0, "SPGrid", "SPGrid::Init() map contents (%s) do not match its name (%s).", &name, m_ZoneFile.c_str()); return false; } // Read the min bounds fread(&m_MinX, sizeof(float), 1, file); fread(&m_MinZ, sizeof(float), 1, file); LogWrite(ZONE__DEBUG, 0, "SPGrid", "minx = %f, minz = %f", m_MinX, m_MinZ); // Read the max bounds fread(&m_MaxX, sizeof(float), 1, file); fread(&m_MaxZ, sizeof(float), 1, file); LogWrite(ZONE__DEBUG, 0, "SPGrid", "maxx = %f, maxz = %f", m_MaxX, m_MaxZ); // Calculate how many cells we need // in both the X and Z direction float width = m_MaxX - m_MinX; float height = m_MaxZ - m_MinZ; m_NumCellsX = ceil(width / m_CellSize); m_NumCellsZ = ceil(height / m_CellSize); LogWrite(ZONE__DEBUG, 0, "SPGrid", "CellSize = %u, x cells = %u, z cells = %u", m_CellSize, m_NumCellsX, m_NumCellsZ); // Allocate all the cells m_Cells.resize(m_NumCellsZ * m_NumCellsX); m_NumFaceCellsX = ceil(width / FACECELLSIZEDEFAULT); m_NumFaceCellsZ = ceil(height / FACECELLSIZEDEFAULT); m_FaceCells.resize(m_NumFaceCellsX * m_NumFaceCellsZ); // Read the number of grids int32 NumGrids; fread(&NumGrids, sizeof(int32), 1, file); LogWrite(ZONE__DEBUG, 0, "SPGrid", "NumGrids = %u", NumGrids); // Loop through the grids loading the face list for (int32 i = 0; i < NumGrids; i++) { // Read the grid id int32 GridID; fread(&GridID, sizeof(int32), 1, file); LogWrite(ZONE__DEBUG, 0, "SPGrid", "GridID = %u", GridID); // Read the number of vertices int32 NumFaces; fread(&NumFaces, sizeof(int32), 1, file); LogWrite(ZONE__DEBUG, 0, "SPGrid", "NumFaces = %u", NumFaces); // Loop through the vertices list reading // 3 at a time to creat a triangle (face) for (int32 y = 0; y < NumFaces; ) { // Each vertex need an x,y,z coordinate and // we will be reading 3 to create the face float x1, x2, x3; float y1, y2, y3; float z1, z2, z3; // Read the first vertex fread(&x1, sizeof(float), 1, file); fread(&y1, sizeof(float), 1, file); fread(&z1, sizeof(float), 1, file); y++; // Read the second vertex fread(&x2, sizeof(float), 1, file); fread(&y2, sizeof(float), 1, file); fread(&z2, sizeof(float), 1, file); y++; // Read the third (final) vertex fread(&x3, sizeof(float), 1, file); fread(&y3, sizeof(float), 1, file); fread(&z3, sizeof(float), 1, file); y++; // Create the face and add it to the grid Face* face = new Face; face->Vertex1[0] = x1; face->Vertex1[1] = y1; face->Vertex1[2] = z1; face->Vertex2[0] = x2; face->Vertex2[1] = y2; face->Vertex2[2] = z2; face->Vertex3[0] = x3; face->Vertex3[1] = y3; face->Vertex3[2] = z3; AddFace(face, GridID); } } fclose(file); /*map >::iterator itr; vector::iterator itr2; for (int32 i = 0; i < m_Cells.size(); i++) { Cell& cell = m_Cells[i]; for (itr = cell.FaceList.begin(); itr != cell.FaceList.end(); itr++) { float min_x = 0.0f; float min_y = 0.0f; float min_z = 0.0f; float max_x = 0.0f; float max_y = 0.0f; float max_z = 0.0f; for (itr2 = (*itr).second.begin(); itr2 != (*itr).second.end(); itr2++) { Face* face = (*itr2); if (min_x == 0.0f || face->Vertex1[0] < min_x) min_x = face->Vertex1[0]; if (face->Vertex2[0] < min_x) min_x = face->Vertex2[0]; if (face->Vertex3[0] < min_x) min_x = face->Vertex3[0]; if (min_y == 0.0f || face->Vertex1[1] < min_y) min_y = face->Vertex1[1]; if (face->Vertex2[1] < min_y) min_y = face->Vertex2[1]; if (face->Vertex3[1] < min_y) min_y = face->Vertex3[1]; if (min_z == 0.0f || face->Vertex1[2] < min_z) min_z = face->Vertex1[2]; if (face->Vertex2[2] < min_z) min_z = face->Vertex2[2]; if (face->Vertex3[2] < min_z) min_z = face->Vertex3[2]; // Max bounds if (max_x == 0.0f || face->Vertex1[0] > max_x) max_x = face->Vertex1[0]; if (face->Vertex2[0] > max_x) max_x = face->Vertex2[0]; if (face->Vertex3[0] > max_x) max_x = face->Vertex3[0]; if (max_y == 0.0f || face->Vertex1[1] > max_y) max_y = face->Vertex1[1]; if (face->Vertex2[1] > max_y) max_y = face->Vertex2[1]; if (face->Vertex3[1] > max_y) max_y = face->Vertex3[1]; if (max_z == 0.0f || face->Vertex1[2] > max_z) max_z = face->Vertex1[2]; if (face->Vertex2[2] > max_z) max_z = face->Vertex2[2]; if (face->Vertex3[2] > max_z) max_z = face->Vertex3[2]; } GridBounds* bounds = new GridBounds; bounds->MinBounds[0] = min_x; bounds->MinBounds[1] = min_y; bounds->MinBounds[2] = min_z; bounds->MaxBounds[0] = max_x; bounds->MaxBounds[1] = max_y; bounds->MaxBounds[2] = max_z; cell.GridBounds[(*itr).first] = bounds; } }*/ return true; } Cell* SPGrid::GetCell(int32 x, int32 z) { if (x >= m_NumCellsX) x = m_NumCellsX - 1; if (z >= m_NumCellsZ) z = m_NumCellsZ - 1; return &m_Cells[z * m_NumCellsX + x]; } Cell* SPGrid::GetCell(float x, float z) { // As cell grid coordinates are all positive we need to // modify the coordinates by subtracting the min bounds float newX = x - m_MinX; float newZ = z - m_MinZ; // Get the cell coordinates by doing int division // with the modified coordinates and the cell size int32 CellX = (int32)(newX / m_CellSize); int32 CellZ = (int32)(newZ / m_CellSize); return GetCell(CellX, CellZ); } FaceCell* SPGrid::GetFaceCell(int32 x, int32 z) { if (x >= m_NumFaceCellsX) x = m_NumFaceCellsX - 1; if (z >= m_NumFaceCellsZ) z = m_NumFaceCellsZ - 1; return &m_FaceCells[z * m_NumFaceCellsX + x]; } FaceCell* SPGrid::GetFaceCell(float x, float z) { // As cell grid coordinates are all positive we need to // modify the coordinates by subtracting the min bounds float newX = x - m_MinX; float newZ = z - m_MinZ; // Get the cell coordinates by doing int division // with the modified coordinates and the cell size int32 CellX = (int32)(newX / FACECELLSIZEDEFAULT); int32 CellZ = (int32)(newZ / FACECELLSIZEDEFAULT); return GetFaceCell(CellX, CellZ); } void SPGrid::AddFace(Face* face, int32 grid) { // As each face has three vertices we will need to check the cell // for all of them and add the face to each cell that it is within face->grid_id = grid; // Get the cell at the first vertex position (X and Z, Y is vertical in EQ2) // as this is the first check we will add it to this cell and compare it // to the other two cells we get for the other two verticies FaceCell* cell = GetFaceCell(face->Vertex1[0], face->Vertex1[2]); cell->FaceList[grid].push_back(face); // Get the cells for the other two verticies and compare FaceCell* cell2 = GetFaceCell(face->Vertex2[0], face->Vertex2[2]); FaceCell* cell3 = GetFaceCell(face->Vertex3[0], face->Vertex3[2]); // If cell 2 is not the same cell as the original cell then add the face to cell2 if (cell2 != cell) cell2->FaceList[grid].push_back(face); // If cell 3 is not the same as the original cell AND not the same as cell 2 then add the face to cell 3 if (cell3 != cell && cell3 != cell2) cell3->FaceList[grid].push_back(face); } float rayIntersectsTriangle(float *p, float *d, float *v0, float *v1, float *v2); int32 SPGrid::GetGridID(Spawn * spawn) { FaceCell* cell = GetFaceCell(spawn->GetX(), spawn->GetZ()); /*if (cell->GridBounds.size() == 1) return cell->FaceList.begin()->first;*/ // Create the starting point for the trace float point[3]; point[0] = spawn->GetX(); point[1] = spawn->GetY() + 3.0f; // Small bump to make sure we are above ground when we do the trace point[2] = spawn->GetZ(); // Create the direction for the trace, as we want what // is below it will just be -1 in the y direction float direction[3]; direction[0] = 0.0f; direction[1] = -1.0f; direction[2] = 0.0f; float MinDistance = 0.0f; int32 Grid = 0; /*map::iterator itr; for (itr = cell->GridBounds.begin(); itr != cell->GridBounds.end(); itr++) { GridBounds* bounds = (*itr).second; if (point[0] >= bounds->MinBounds[0] && point[1] >= bounds->MinBounds[1] && point[2] >= bounds->MinBounds[2] && point[0] <= bounds->MaxBounds[0] && point[1] <= bounds->MaxBounds[1] && point[2] <= bounds->MaxBounds[2]) { vector::iterator itr2; for (itr2 = cell->FaceList[(*itr).first].begin(); itr2 != cell->FaceList[(*itr).first].end(); itr2++) { Face* face = *itr2; float distance; if ((distance = rayIntersectsTriangle(point, direction, face->Vertex1, face->Vertex2, face->Vertex3)) != 0) { if (MinDistance == 0.0f || distance < MinDistance) { MinDistance = distance; Grid = (*itr).first; } } } } }*/ map >::iterator mapitr; for (mapitr = cell->FaceList.begin(); mapitr != cell->FaceList.end(); mapitr++) { vector::iterator itr; for (itr = (*mapitr).second.begin(); itr != (*mapitr).second.end(); itr++) { Face* face = *itr; float distance; if ((distance = rayIntersectsTriangle(point, direction, face->Vertex1, face->Vertex2, face->Vertex3)) != 0) { if (MinDistance == 0.0f || distance < MinDistance) { MinDistance = distance; Grid = (*mapitr).first; } } } } return Grid; } int32 SPGrid::GetGridIDByLocation(float x, float y, float z) { FaceCell* cell = GetFaceCell(x, z); /*if (cell->GridBounds.size() == 1) return cell->FaceList.begin()->first;*/ // Create the starting point for the trace float point[3]; point[0] = x; point[1] = y + 3.0f; // Small bump to make sure we are above ground when we do the trace point[2] = z; // Create the direction for the trace, as we want what // is below it will just be -1 in the y direction float direction[3]; direction[0] = 0.0f; direction[1] = -1.0f; direction[2] = 0.0f; float MinDistance = 0.0f; int32 Grid = 0; /*map::iterator itr; for (itr = cell->GridBounds.begin(); itr != cell->GridBounds.end(); itr++) { GridBounds* bounds = (*itr).second; if (point[0] >= bounds->MinBounds[0] && point[1] >= bounds->MinBounds[1] && point[2] >= bounds->MinBounds[2] && point[0] <= bounds->MaxBounds[0] && point[1] <= bounds->MaxBounds[1] && point[2] <= bounds->MaxBounds[2]) { vector::iterator itr2; for (itr2 = cell->FaceList[(*itr).first].begin(); itr2 != cell->FaceList[(*itr).first].end(); itr2++) { Face* face = *itr2; float distance; if ((distance = rayIntersectsTriangle(point, direction, face->Vertex1, face->Vertex2, face->Vertex3)) != 0) { if (MinDistance == 0.0f || distance < MinDistance) { MinDistance = distance; Grid = (*itr).first; } } } } }*/ map >::iterator mapitr; for (mapitr = cell->FaceList.begin(); mapitr != cell->FaceList.end(); mapitr++) { vector::iterator itr; for (itr = (*mapitr).second.begin(); itr != (*mapitr).second.end(); itr++) { Face* face = *itr; float distance; if ((distance = rayIntersectsTriangle(point, direction, face->Vertex1, face->Vertex2, face->Vertex3)) != 0) { if (MinDistance == 0.0f || distance < MinDistance) { MinDistance = distance; Grid = (*mapitr).first; } } } } return Grid; } float SPGrid::GetBestY(float x, float y, float z) { float temp_y = 0; float best_y = 999999.0f; FaceCell* startCell = GetFaceCell(x, z); float tmpY = y + 0.5f; float point[3]; point[0] = x; point[1] = tmpY; // Small bump to make sure we are above ground when we do the trace point[2] = z; float MinDistance = 0.0f; // Create the direction for the trace, as we want what // is below it will just be -1 in the y direction float direction[3]; direction[0] = 0.0f; direction[1] = -1.0f; direction[2] = 0.0f; Face* lastFace = 0; int32 Grid = 0; float BestZ = -999999.0f; map >::iterator mapitr; for (mapitr = startCell->FaceList.begin(); mapitr != startCell->FaceList.end(); mapitr++) { vector::iterator itr; for (itr = (*mapitr).second.begin(); itr != (*mapitr).second.end(); itr++) { Face* face = *itr; float distance; if ((distance = rayIntersectsTriangle(point, direction, face->Vertex1, face->Vertex2, face->Vertex3)) != 0) { if (MinDistance == 0.0f || distance < MinDistance) { BestZ = face->Vertex2[1]; MinDistance = distance; lastFace = face; Grid = (*mapitr).first; } } } } printf("GridID: %i, BestZ: %f yIn:% f\n", Grid, BestZ, y); float endY = 999999.0f; if (lastFace) { /* for (int i = 0; i < 3; i++) { for (int z = 0; z < 3; z++) { if (i == 0) printf("Face%i-%i: %f\n", i, z, lastFace->Vertex1[z]); else if (i == 1) printf("Face%i-%i: %f\n", i, z, lastFace->Vertex2[z]); else if (i == 2) printf("Face%i-%i: %f\n", i, z, lastFace->Vertex3[z]); } }*/ endY = lastFace->Vertex2[1]; } return endY; } Face* SPGrid::GetClosestFace(float x, float y, float z) { float temp_y = 0; float best_y = 999999.0f; FaceCell* startCell = GetFaceCell(x, z); float tmpY = y + 0.5f; float point[3]; point[0] = x; point[1] = tmpY; // Small bump to make sure we are above ground when we do the trace point[2] = z; float MinDistance = 0.0f; // Create the direction for the trace, as we want what // is below it will just be -1 in the y direction float direction[3]; direction[0] = 0.0f; direction[1] = -1.0f; direction[2] = 0.0f; Face* lastFace = 0; int32 Grid = 0; float BestZ = -999999.0f; map >::iterator mapitr; for (mapitr = startCell->FaceList.begin(); mapitr != startCell->FaceList.end(); mapitr++) { vector::iterator itr; for (itr = (*mapitr).second.begin(); itr != (*mapitr).second.end(); itr++) { Face* face = *itr; float distance; if ((distance = rayIntersectsTriangle(point, direction, face->Vertex1, face->Vertex2, face->Vertex3)) != 0) { if (MinDistance == 0.0f || distance < MinDistance) { BestZ = face->Vertex2[1]; MinDistance = distance; lastFace = face; Grid = (*mapitr).first; } } } } return lastFace; } Face* SPGrid::FindPath(float x, float y, float z, float targX, float targY, float targZ, bool forceEndCell) { float MinDistance = 0.0f; float MinDistanceEnd = 999999.0f; // Create the starting point for the trace float point[3]; point[0] = x; point[1] = y + 1.0f; // Small bump to make sure we are above ground when we do the trace point[2] = z; float pointEnd[3]; pointEnd[0] = targX; pointEnd[1] = y + 1.0f; // Small bump to make sure we are above ground when we do the trace pointEnd[2] = targZ; // Create the direction for the trace, as we want what // is below it will just be -1 in the y direction float direction[3]; if (!forceEndCell) { if (targX > x) direction[0] = -0.5f; else direction[0] = 0.5f; } else { if (targX > x) direction[0] = 1.0f; else// if (targZ < z) direction[0] = -1.0f; } //if (targY < y) direction[1] = -1.0f; //else // direction[1] = .5f; //direction[1] = -1.0f; if (forceEndCell) { if (targZ > z) direction[2] = -0.5f; else direction[2] = 0.5f; } else { if (targZ > z) direction[2] = 1.0f; else// if ( targX < x ) direction[2] = -1.0f; } FaceCell* startCell = GetFaceCell(x, z); FaceCell* endCell = GetFaceCell(x, z); Face* startFace = GetClosestFace(x, y, z); if (startFace == NULL) return 0; //float tmpDistance = rayIntersectsTriangle(pointEnd, direction, startFace->Vertex1, startFace->Vertex2, startFace->Vertex3); //if (tmpDistance != 0.0f && tmpDistance < 15.0f) // return 0; Face* nextFace = 0; Face* endFace = GetClosestFace(targX, targY, targZ); float distBetweenEachOther = 999999.0f; map >::iterator mapitr; if (endFace != NULL && startCell->FaceList.count(endFace->grid_id)) mapitr = startCell->FaceList.find(endFace->grid_id); else if (startFace != NULL) mapitr = startCell->FaceList.find(startFace->grid_id); else return 0; //FILE* pFile; //pFile = fopen("vertices.txt", "a+"); char msg[256]; //_snprintf(msg, 256, "%f %f %f - %f %f %f\n", x,y,z,targX,targY,targZ); //fwrite(msg, 1, strnlen(msg, 256), pFile); for (; mapitr != startCell->FaceList.end(); mapitr++) { vector::iterator itr; for (itr = (*mapitr).second.begin(); itr != (*mapitr).second.end(); itr++) { Face* face = *itr; float distance; float distanceend; distance = rayIntersectsTriangle(point, direction, face->Vertex1, face->Vertex2, face->Vertex3); //distanceend = rayIntersectsTriangle(pointEnd, direction, face->Vertex1, face->Vertex2, face->Vertex3); float tmpx1 = face->Vertex1[0] - pointEnd[0]; float tmpy1 = face->Vertex1[1] - pointEnd[1]; float tmpz1 = face->Vertex1[2] - pointEnd[2]; float tmpDistBetweenEachOther = sqrt(tmpx1 * tmpx1 + tmpy1 * tmpy1 + tmpz1 * tmpz1); snprintf(msg, 256, "%f (%f): Face: %f %f %f\n", tmpDistBetweenEachOther, distance, face->Vertex1[0], face->Vertex1[1], face->Vertex1[2]); if (face == startFace) { printf("Hit Start Cell..%s\n",msg); break; } else if (face == endFace) { printf("Hit End Cell..%s\n",msg); //continue; } //fwrite(msg, 1, strnlen(msg,256), pFile); //printf("%f: Face: %f %f %f... distance: %f..\n", tmpDistBetweenEachOther, face->Vertex1[0], face->Vertex1[1], face->Vertex1[2],distance); if (distance > 0.0f && ((MinDistance == 0.0f || distance < MinDistance) || (tmpDistBetweenEachOther < distBetweenEachOther))) { printf("%f (%f): !HIT! Face: %f %f %f\n", tmpDistBetweenEachOther, distance, face->Vertex1[0], face->Vertex1[1], face->Vertex1[2]); distBetweenEachOther = tmpDistBetweenEachOther; nextFace = face; MinDistance = distance; } } } /* fwrite("\n", sizeof(char), 1, pFile); if (forceEndCell) fwrite("Y", sizeof(char), 1, pFile); fwrite("\n\n", sizeof(char), 2, pFile); fclose(pFile);*/ Face* anotherAttempt = 0; if (!forceEndCell) { printf("ForceEndCellSet:\n"); anotherAttempt = FindPath(x, y, z, targX, targY, targZ, true); } if (!nextFace) { if (anotherAttempt) nextFace = anotherAttempt; else nextFace = endFace; /*if (!forceEndCell) return FindPath(x, y, z, targX, targY, targZ, true); nextFace = endFace;*/ } return nextFace; } /********************************************************************** Math functions/macros to test a ray intersection in 3D space **********************************************************************/ /* a = b - c */ #define vector(a,b,c) \ (a)[0] = (b)[0] - (c)[0]; \ (a)[1] = (b)[1] - (c)[1]; \ (a)[2] = (b)[2] - (c)[2]; #define crossProduct(a,b,c) \ (a)[0] = (b)[1] * (c)[2] - (c)[1] * (b)[2]; \ (a)[1] = (b)[2] * (c)[0] - (c)[2] * (b)[0]; \ (a)[2] = (b)[0] * (c)[1] - (c)[0] * (b)[1]; #define innerProduct(v,q) \ ((v)[0] * (q)[0] + \ (v)[1] * (q)[1] + \ (v)[2] * (q)[2]) // all parameters should be vectors (float[3]) float rayIntersectsTriangle(float *p, float *d, float *v0, float *v1, float *v2) { float e1[3], e2[3], h[3], s[3], q[3]; float a, f, u, v; vector(e1, v1, v0); vector(e2, v2, v0); crossProduct(h, d, e2); a = innerProduct(e1, h); if (a > -0.00001 && a < 0.00001) return 0; f = 1 / a; vector(s, p, v0); u = f * (innerProduct(s, h)); if (u < 0.0 || u > 1.0) return 0; crossProduct(q, s, e1); v = f * innerProduct(d, q); if (v < 0.0 || u + v > 1.0) return 0; // at this stage we can compute t to find out where // the intersection point is on the line float t = f * innerProduct(e2, q); if (t > 0.00001) // ray intersection return t; else // this means that there is a line intersection // but not a ray intersection return 0; }