/********************************************************
* To check whether 2 lines segments have an intersection
*********************************************************/
public bool IntersectedWith(CLineSegment 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) < CPolygon.thresh) //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 ((ub > 0) && (ub < 1))
{
return(true);
}
else
{
return(false);
}
}
else //lines are parallel
{
return(false);
}
}
/***Check whether this line is in a longer line***/
public bool InLine(CLineSegment longerLineSegment)
{
bool bInLine = false;
if (longerLineSegment.PointInLine(m_startPoint) &&
longerLineSegment.PointInLine(m_endPoint))
{
bInLine = true;
}
return(bInLine);
}
/**********************************************************
* 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(Vector2d[] trianglePts, Vector2d pt)
{
if (trianglePts.Length != 3)
{
return(false);
}
for (int i = trianglePts.GetLowerBound(0);
i < trianglePts.GetUpperBound(0); i++)
{
if (pt.EqualsPoint(trianglePts[i]))
{
return(true);
}
}
bool bIn = false;
CLineSegment line0 = new CLineSegment(trianglePts[0], trianglePts[1]);
CLineSegment line1 = new CLineSegment(trianglePts[1], trianglePts[2]);
CLineSegment line2 = new CLineSegment(trianglePts[2], trianglePts[0]);
if (line0.PointInLine(pt) || line1.PointInLine(pt) || line2.PointInLine(pt))
{
bIn = true;
}
else //point is not in the lines
{
double dblArea0 = CPolygon.PolygonArea(new Vector2d[] { trianglePts[0], trianglePts[1], pt });
double dblArea1 = CPolygon.PolygonArea(new Vector2d[] { trianglePts[1], trianglePts[2], pt });
double dblArea2 = CPolygon.PolygonArea(new Vector2d[] { 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);
}
/************************************************
* 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 CLineSegment 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
CLineSegment line;
MyVector2 newStartPoint = new MyVector2();
MyVector2 newEndPoint = new MyVector2();
double alphaInRad = this.GetLineAngle(); // 0-PI
if (rightOrDown)
{
if (this.HorizontalLine()) //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 CLineSegment(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 CLineSegment(
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 CLineSegment(
newStartPoint, newEndPoint);
}
}
} //{rightOrDown}
else //leftOrUp
{
if (this.HorizontalLine()) //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 CLineSegment(
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 CLineSegment(
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 CLineSegment(
newStartPoint, newEndPoint);
}
}
}
return(line);
}
