/**********************************************************
* To check the Pt is in the Triangle or not.
* If the Pt is in the line or is a vertex, then return true.
* If the Pt is out of the Triangle, then return false.
*
* This method is used for triangle only.
***********************************************************/
private bool TriangleContainsPoint(Coordinate[] trianglePts, Coordinate pt)
{
if (trianglePts.Length != 3)
{
return(false);
}
for (int i = trianglePts.GetLowerBound(0);
i < trianglePts.GetUpperBound(0); i++)
{
if (pt.Equals(trianglePts[i]))
{
return(true);
}
}
bool bIn = false;
LineSegmentEquation line0 = new LineSegmentEquation(
trianglePts[0], trianglePts[1]);
LineSegmentEquation line1 = new LineSegmentEquation(
trianglePts[1], trianglePts[2]);
LineSegmentEquation line2 = new LineSegmentEquation(
trianglePts[2], trianglePts[0]);
if (line0.OnLine(pt) || line1.OnLine(pt) || line2.OnLine(pt))
{
bIn = true;
}
else //point is not in the lines
{
double dblArea0 = PolygonHelper.PolygonArea(
new Coordinate[] { trianglePts[0], trianglePts[1], pt });
double dblArea1 = PolygonHelper.PolygonArea(
new Coordinate[] { trianglePts[1], trianglePts[2], pt });
double dblArea2 = PolygonHelper.PolygonArea(
new Coordinate[] { trianglePts[2], trianglePts[0], pt });
if (dblArea0 > 0)
{
if ((dblArea1 > 0) && (dblArea2 > 0))
{
bIn = true;
}
}
else if (dblArea0 < 0)
{
if ((dblArea1 < 0) && (dblArea2 < 0))
{
bIn = true;
}
}
}
return(bIn);
}
/***Check whether this line is in a longer line***/
public bool InLine(LineSegmentEquation longerLineSegment)
{
if (longerLineSegment == null)
{
throw new ArgumentNullException("longerLineSegment");
}
bool bInLine = false;
if ((longerLineSegment.OnLine(m_startPoint)) &&
(longerLineSegment.OnLine(m_endPoint)))
{
bInLine = true;
}
return(bInLine);
}
/********************************************************
* To check whether 2 lines segments have an intersection
*********************************************************/
public bool IntersectedWith(LineSegmentEquation line)
{
if (line == null)
{
throw new ArgumentNullException("line");
}
double x1 = this.m_startPoint.X;
double y1 = this.m_startPoint.Y;
double x2 = this.m_endPoint.X;
double y2 = this.m_endPoint.Y;
double x3 = line.m_startPoint.X;
double y3 = line.m_startPoint.Y;
double x4 = line.m_endPoint.X;
double y4 = line.m_endPoint.Y;
double de = (y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1);
//if de<>0 then //lines are not parallel
if (Math.Abs(de - 0) < ConstantValue.SmallValue) //not parallel
{
double ua = ((x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3)) / de;
double ub = ((x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3)) / de;
if ((ua > 0) && (ub < 1))
{
return(true);
}
else
{
return(false);
}
}
else //lines are parallel
{
return(false);
}
}
/************************************************
* Offset the line segment to generate a new line segment
* If the offset direction is along the x-axis or y-axis,
* Parameter is true, other wise it is false
* ***********************************************/
public LineSegmentEquation OffsetLine(double distance, bool rightOrDown)
{
//offset a line with a given distance, generate a new line
//rightOrDown=true means offset to x incress direction,
// if the line is horizontal, offset to y incress direction
LineSegmentEquation line;
Coordinate newStartPoint = new Coordinate();
Coordinate newEndPoint = new Coordinate();
double alphaInRad = this.LineAngle; // 0-PI
if (rightOrDown)
{
if (this.IsHorizontalLine) //offset to y+ direction
{
newStartPoint.X = this.m_startPoint.X;
newStartPoint.Y = this.m_startPoint.Y + distance;
newEndPoint.X = this.m_endPoint.X;
newEndPoint.Y = this.m_endPoint.Y + distance;
line = new LineSegmentEquation(newStartPoint, newEndPoint);
}
else //offset to x+ direction
{
if (Math.Sin(alphaInRad) > 0)
{
newStartPoint.X = m_startPoint.X + Math.Abs(distance * Math.Sin(alphaInRad));
newStartPoint.Y = m_startPoint.Y - Math.Abs(distance * Math.Cos(alphaInRad));
newEndPoint.X = m_endPoint.X + Math.Abs(distance * Math.Sin(alphaInRad));
newEndPoint.Y = m_endPoint.Y - Math.Abs(distance * Math.Cos(alphaInRad));
line = new LineSegmentEquation(
newStartPoint, newEndPoint);
}
else //sin(FalphaInRad)<0
{
newStartPoint.X = m_startPoint.X + Math.Abs(distance * Math.Sin(alphaInRad));
newStartPoint.Y = m_startPoint.Y + Math.Abs(distance * Math.Cos(alphaInRad));
newEndPoint.X = m_endPoint.X + Math.Abs(distance * Math.Sin(alphaInRad));
newEndPoint.Y = m_endPoint.Y + Math.Abs(distance * Math.Cos(alphaInRad));
line = new LineSegmentEquation(
newStartPoint, newEndPoint);
}
}
} //{rightOrDown}
else //leftOrUp
{
if (this.IsHorizontalLine) //offset to y directin
{
newStartPoint.X = m_startPoint.X;
newStartPoint.Y = m_startPoint.Y - distance;
newEndPoint.X = m_endPoint.X;
newEndPoint.Y = m_endPoint.Y - distance;
line = new LineSegmentEquation(
newStartPoint, newEndPoint);
}
else //offset to x directin
{
if (Math.Sin(alphaInRad) >= 0)
{
newStartPoint.X = m_startPoint.X - Math.Abs(distance * Math.Sin(alphaInRad));
newStartPoint.Y = m_startPoint.Y + Math.Abs(distance * Math.Cos(alphaInRad));
newEndPoint.X = m_endPoint.X - Math.Abs(distance * Math.Sin(alphaInRad));
newEndPoint.Y = m_endPoint.Y + Math.Abs(distance * Math.Cos(alphaInRad));
line = new LineSegmentEquation(
newStartPoint, newEndPoint);
}
else //sin(FalphaInRad)<0
{
newStartPoint.X = m_startPoint.X - Math.Abs(distance * Math.Sin(alphaInRad));
newStartPoint.Y = m_startPoint.Y - Math.Abs(distance * Math.Cos(alphaInRad));
newEndPoint.X = m_endPoint.X - Math.Abs(distance * Math.Sin(alphaInRad));
newEndPoint.Y = m_endPoint.Y - Math.Abs(distance * Math.Cos(alphaInRad));
line = new LineSegmentEquation(
newStartPoint, newEndPoint);
}
}
}
return(line);
}
