// vec2_LineStart = cVector_2d.MakeVector(aptDefinitionPoints[iLast].x,aptDefinitionPoints[iLast].y);
// vec2_LineEnd = cVector_2d.MakeVector(aptDefinitionPoints[i].x,aptDefinitionPoints[i].y);
// vec2_Point = cVector_2d.MakeVector(cptPointToAdd.x,cptPointToAdd.y);
// nDistance = cVector_2d.DistanceOfPointToLine(vec2_Point, vec2_LineStart, vec2_LineEnd);
// vec2_VecLine = cVector_2d.VectorSubtract(vec2_LineStart, vec2_LineEnd);
// cptIntersectionPoint = cVector_2d.GetPointVerticalIntersection(aptDefinitionPoints[i], vec2_VecLine, cptPointToAdd);
// cVector_2d.GetPointVerticalIntersection(aptDefinitionPoints[i], vec2_VecLine, cptPointToAdd);
// vecInputLine: vector/line between two polygon points
// cptPointQ: Origin of vector vecInputLine, one of the two polygon points
// cpPointP: Click point
// Schnittpunkt zwischen Normale zu vecInputLine und cpPointP auf vecInputLine
public static cPoint GetPointVerticalIntersection(cPoint cptPointQ, cVector_2d vecInputLine, cPoint cpPointP)
{
// Q: Line start/endpoint
// P + a * vecNormalVector = Intersection = Q + b * vecInputLine
// a = (-(Px*vy-Py*vx-Qx*vy+Qy*vx))/(nx*vy-ny*vx)
// b = (-(Px*ny-Py*nx-Qx*ny+Qy*nx))/(nx*vy-ny*vx)
cVector_2d vecNormalVector = GetNormalVector(vecInputLine);
double nDenominator = vecNormalVector.x * vecInputLine.y - vecNormalVector.y * vecInputLine.x;
cPoint cptIntersectionPoint = new cPoint();
if (nDenominator == 0)
{
// no intersection
cptIntersectionPoint.bHasInterSection = false;
return(cptIntersectionPoint);
}
double a = (-(cpPointP.x * vecInputLine.y - cpPointP.y * vecInputLine.x - cptPointQ.x * vecInputLine.y + cptPointQ.y * vecInputLine.x)) / nDenominator;
double b = (-(cpPointP.x * vecNormalVector.y - cpPointP.y * vecNormalVector.x - cptPointQ.x * vecNormalVector.y + cptPointQ.y * vecNormalVector.x)) / nDenominator;
cptIntersectionPoint.bHasInterSection = true;
cptIntersectionPoint.x = cpPointP.x + a * vecNormalVector.x;
cptIntersectionPoint.y = cpPointP.y + a * vecNormalVector.y;
return(cptIntersectionPoint);
}
} // End Constructor
public static cVector_2d GetNormalVector(cVector_2d vec)
{
return(null);
}